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  • 1. Ah-King, Malin
    et al.
    Elofsson, Helena
    Kvarnemo, Charlotta
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Why is there no sperm competition in a pipefish with externally brooding males? Insights from sperm activitation and morphology2006In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 68, no 3, p. 958-962Article in journal (Refereed)
    Abstract [en]

    Nerophis ophidion sperm activation and morphology were investigated with the aim of explaining the apparent lack of sperm competition in this syngnathid with externally brooding males. Nerophis ophidion sperm were activated by a mixture of ovarian fluid and sea water, but not by sea water alone. This indicated that sperm were not shed into the water but needed to be released near the eggs, which probably restrained sperm competition.

  • 2.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Forsgren, Elisabet
    Norsk institutt for naturforskning i Trondheim, Norway.
    Karlsson, Anna
    Enheten för biologisk mångfald och områdesskydd, Havs och Vattenmyndigheten, Göteborg.
    Kvarnemo, Charlotta
    Zoologi, Göteborgs universitet, Göteborg.
    Magnhagen, Carin
    Fiskbiologi, Sveriges lantbruksuniversitet (SLU), Umeå.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Natural Resources and Sustainable Development. Etologi, NTNU, Trondheim, Norway.
    Östlund Nilsson, Sara
    Nasjonalbiblioteket, Oslo, Norway.
    En beteende-ekologisk forskningsperiod på Klubbans biologiska station: Rapport från återträff med Doktorer som disputerade (1983-2001) på avhandlingar med fältarbete på Klubbans Biologiska station. I en värld av kantnålar, stubbar, spiggar och nudingar.2018Report (Other (popular science, discussion, etc.))
    Abstract [en]

    We had the fortune as PhD-students and scientists in Animal Ecology at Uppsala University, to spend joyful and creative field work summers at Klubban Biological Station, during the 1980-90’s. A reunion in June 2018 resulted in this report highlighting research on pipefishes, gobies, sticklebacks and nudibranchs. Our research on these animals have provided novel insights and knowledge of the process of sexual selection and paternal care. These animals have, in many aspects, now become model organisms in evolutionary behavioral ecology in marine environments. Our list of publications provides many examples of how environmental factors influence how sexual selection and mate choice operate, how predictors like potential reproductive rates, operational sex ratios work and how male parental care is prominent in influencing selection. This research, that started at Klubban, has broadened our understanding of the ecological importance of shallow marine areas. The evolutionary understanding of how males and females can behave and how adaptive traits are selected in interaction with social and an increasingly changing ambient environment is in focus in our continued scientific endeavors. We have happily compiled this report illustrating how science and scientist can stimulate each other at a wonderful place like Klubban Biological Station, with the access to amazing organisms like pipefishes, gobies, sticklebacks and nudibranchs.

  • 3. Aronsen, T.
    et al.
    Mobley, K. B.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sundin, Josefin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Billing, A. M.
    Rosenqvist, G.
    The operational sex ratio and density influence spatial relationships between breeding pipefish2013In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 24, no 4, p. 888-897Article in journal (Refereed)
    Abstract [en]

    The operational sex ratio (ratio of sexually receptive males to females) has been extensively studied in behavioral ecology, whereas other demographic factors such as the effect of density on mating behavior have received less empirical attention. We manipulated mating competition by establishing breeding populations of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) at 2 sex ratios (male biased or female biased) and 2 densities. We used mean crowding (m*) and the index of association (X) to measure spatial distributions within and between the sexes, respectively, and investigated how these measures reflect the predicted strength of mating competition. In general, female m* increased as fewer males were available for mating, which suggests increased intrasexual competition in the most competitive sex. However, male m* also increased as the operational sex ratio became more female biased, suggesting that m* did not reflect mating competition for males. Association between the sexes (X) was higher under male bias than female bias, probably because males were still available for mating under male bias. In addition, X decreased in the female-biased treatment as the operational sex ratio became even more female biased. Higher density increased m* in both sex ratios and sexes, although for both sexes in the female-biased high-density treatment the operational sex ratio did not influence m*, probably because femalefemale competition inhibits further crowding in this treatment. In this study, we show that the use of m* and X can be a useful tool in behavioral studies but their interpretation requires detailed information about the mating system. Therefore, we recommend caution with their broadscale application.

  • 4. Aronsen, Tonje
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Mobley, Kenyon B.
    Ratikainen, Irja I.
    Rosenqvist, Gunilla
    Sex Ratio And Density Affect Sexual Selection In A Sex-Role Reversed Fish2013In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 67, no 11, p. 3243-3257Article in journal (Refereed)
    Abstract [en]

    Understanding how demographic processes influence mating systems is important to decode ecological influences on sexual selection in nature. We manipulated sex ratio and density in experimental populations of the sex-role reversed pipefish Syngnathus typhle. We quantified sexual selection using the Bateman gradient (beta'ss), the opportunity for selection (I), and sexual selection (Is), and the maximum standardized sexual selection differential (s(max)). We also measured selection on body length using standardized selection differentials (s') and mating differentials (m'), and tested whether the observed I and Is differ from values obtained by simulating random mating. We found that I, Is, and s'(max), but not beta'(ss), were higher for females under female than male bias and the opposite for males, but density did not affect these measures. However, higher density decreased sexual selection (m similar to but not s') on female length, but selection on body length was not affected by sex ratio. Finally, Is but not I was higher than expected from random mating, and only for females under female bias. This study demonstrates that both sex ratio and density affect sexual selection and that disentangling interrelated demographic processes is essential to a more complete understanding of mating behavior and the evolution of mating systems.

  • 5.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Are female ornaments different from those of males? The pipefish evidence1999In: Behaviour and Conservation of Littoral Fishes: Based on the symposium "Behaviour and Conservation of littoral fishes" held at ISPA(Lisboa) 0n 15-18 April 1998 / [ed] Almada, V.C., Oliveira, R.F. & Gonçalves, E.J., Lisboa: ISPA , 1999, p. 231-248Chapter in book (Other academic)
  • 6.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Coexistence, size overlap and population regulation in tidal vs non-tidal Palaemon prawns1982In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 54, no 1, p. 1-7Article in journal (Refereed)
    Abstract [en]

    The effect of increased habitat heterogeneity in tidal areas on coexistence between Palaemon prawns was studied at eight sites along the European Atlantic coast. Two species which are sympatric in non-tidal areas, Palaemon adspersus Rathke and P. squilla (L.) are largely allopatric in tidal areas, and the sympatric size difference decreases in allopatry. In tidal areas the smaller species, P. squilla, is restricted to brown algal belts and rockpools. A third species, P. serratus (Pennant), larger than the others, occurs under oceanic salinities in subtidal brown algal belts and there has forced P. squilla to restrict its habitat distribution to adjacent intertidal rockpools. At estuarine salinities, however, P. squilla also inhabits the brown algal belts. A larger diel variation in stomach fullness index in P. squilla than in P. adspersus persists in non-tidal areas. Abiotic factors probably restrict the two largest species, viz. P. adspersus and P. serratus, to subtidal environments; these species are sensitive to the extremes in salinity, temperature or O2 levels characteristic of the intertidal zone. Competition and/or predation probably relegates P. squilla to the intertidal zone. In non-tidal areas, where this zone is reduced, P. squilla increases its niche width and coexists with P. adspersus, and the size differentiation associated with sympatry may reduce interspecific competition.

  • 7.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Different reproductive success at low salinity determines the estuarine distribution of two Palaemon prawn species1985In: Holarctic ecology, ISSN 0105-9327, Vol. 8, no 1, p. 49-52Article in journal (Refereed)
  • 8.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Egg competition in a sex-role reversed pipefish: subdominant females trade reproduction for growth1991In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 45, no 3, p. 770-774Article in journal (Refereed)
  • 9.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Evolutionary biology: Pregnant fathers in charge2010In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 464, no 7287, p. 364-365Article in journal (Refereed)
  • 10.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Many mates make male pipefish choosy1995In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 132, no 3-4, p. 213-218Article in journal (Refereed)
    Abstract [en]

    In the sex-role reversed pipefish Syngnathus typhle males search for mates, and prefer to mate with large rather than small females. When mate density was experimentally manipulated, males exerted a mate choice only under high mate density, whereas no mate choice could be demonstrated under low mate density. Hence, when males are infrequently encountered, males reduce the costs associated with an extended mate search by accepting females that otherwise would have been rejected.

  • 11.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Mating systems and sex allocation1997In: Behavioural Ecology of Teleost Fishes / [ed] Godin, J.-G. J., Oxford: Oxford Univ. Press , 1997, p. 237-265Chapter in book (Other academic)
  • 12.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Niche differentiation between two littoral prawns in Gullmar Fjord, Sweden: Palaemon adsperus and P. squilla1980In: Holarctic ecology, ISSN 0105-9327, Vol. 3, no 2, p. 111-115Article in journal (Refereed)
  • 13.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Parental care: why, who and how much? Book review of "The evolution of Parental Care" by T. H. Clutton-Brock1992In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 7, no 2, p. 67-68Article, book review (Other academic)
  • 14.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Population biology of two Palaemon prawn species in western Europe1983Doctoral thesis, comprehensive summary (Other academic)
  • 15.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reproductive adaptations in two Palaemon prawn species with differing habitat requirements1984In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 17, no 1, p. 77-83Article in journal (Refereed)
  • 16.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Risky sex: male pipefishes mate at random in the presence of a predator1993In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 46, no 1, p. 169-175Article in journal (Refereed)
    Abstract [en]

    Whether the presence of a predator alters courtship behaviour and mating in male pipefish, Syngnathus typhle, was studied experimentally by first allowing a male to choose between a large and a small female in an enclosure. The females were subsequently released to establish with which the male mated. In the presence of an enclosed predator, males were not more active in front of or danced more with larger than smaller females, but in the absence of a predator the larger females received more activity and dancing. Moreover, control males (without a predator) copulated more often with large than with small females, whereas predator-exposed males copulated infrequently and indiscriminately. These differences are most likely to be due to a decrease in male choosiness when a predator is present, as treatment, size and time of the day did not influence the activity of enclosed females. Predator-exposed males courted and copulated less, but each copulation transferred more eggs, compared with the control males. There was no significant difference in total number of eggs transferred to the males' brood pouches between treatments. Thus, the presence of a predator made mating random and minimized conspicuous mating behaviour, thereby decreasing the potential for sexual selection to act under high predation regimes in this pipefish.

  • 17.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Sequential hermaphroditism and the size-advantage hypothesis: an experimental test1990In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 39, no 3, p. 426-433Article in journal (Refereed)
    Abstract [en]

    When members of one sex have a low reproductive success when small and a high reproductive success when large, while members of the opposite sex do relatively better when small and relatively worse when large, sequential hermaphroditism is commonly believed to be favoured by natural selection. This so-called size-advantage hypothesis has not been rigorously tested experimentally. For the hermaphrodite Ophryotrocha puerilis puerilis, a polychaete, in which small individuals are males and large ones females, the hypothesis predicts that reproductive success will increase less with body size for males than for females, eventually promoting sex change in males. Dry body weight of males was not correlated with reproductive rate, whereas there was a positive correlation for females in reproducing pairs. Furthermore, an increment in the size of females affected clutch size and reproductive rate more than did an equal increment in the size of males. Reproductive success of males decreased with size, because females preferred smaller males. At the same time, large males won contests for access to females, although female choice overrode this combat superiority. Therefore, after reaching a certain size a male would not benefit from staying male. Taking into account the relatively low cost of sex change in this species (about 5 days being lost, equivalent to one interbrood interval) sex reversal occurred as predicted by the size-advantage hypothesis.

  • 18.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Sex dimorphism and skewed sex-ratios in the prawn species Palaemon adspersus and P. squilla1981In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 36, no 2, p. 158-162Article in journal (Refereed)
  • 19.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Sex role reversal in a pipefish: female ornaments as amplifying handicaps2000In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 37, no 1, p. 1-13Article in journal (Refereed)
    Abstract [en]

    The reasons for sex role reversal in the pipefish Syngnathus typhle are reviewed. In this species, females compete for males, which are choosier than females. Before mating, females display a sexual ornament, a cross-wise striped pattern along their body sides. This ornament is here shown to be an amplifier that facilitates for males to tell females of different sizes apart (males prefer larger females). When students were asked to compare bar sizes, where bars differed in "ornamentation", accuracy in estimating size was highest with "heavy ornamented" as compared with "intermediate" or "not ornamented" bars. Moreover, bar size was more accurately judged with crosswise than with lengthwise striped bars, explaining why stripes run cross- rather than lengthwise in females. The ornament is probably costly (it reduces crypsis and may be socially provocative), and it is also attractive to males. Thus, the ornament is best described as an amplifying handicap.

  • 20.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Sex-change by a polychaete: effects of social and reproductive costs1986In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 67, no 4, p. 837-845Article in journal (Refereed)
  • 21.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    The operational sex-ratio influences choosiness in a pipefish1994In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 5, no 3, p. 254-258Article in journal (Refereed)
    Abstract [en]

    If more females than males are available for mating in the breeding population (i.e., the operational sex ratio, OSR, is female biased), males can afford to be choosy. In the pipefish (Syngnathus typhle) females compete for males, who are choosy. In nature OSRs are typically female biased, but may occasionally be male biased. In a series of experiments, males were allowed to choose between a large and a small female under a perceived excess of either males or females. Under female bias, males preferred the large female: they spent more time close to her than to the small female; they courted the large female sooner than the small; and they tended to copulate sooner and more often with the large female. Under male bias all these differences vanished and males mated at random with respect to female size. Males reproduced at a faster rate under male than under female bias because they received more eggs in their brood pouches. Thus, males switched from maximizing mate quality (i.e., being choosy) to minimizing the risk of not reproducing (i.e., being quick) as the OSR became male biased.

  • 22.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    The ups and downs of parental care2013In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 28, no 7, p. 387-388Article, book review (Other academic)
  • 23.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    To change or not to change sex : A comparison between two Ophryotrocha species (Polychaeta)1991In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 5, no 2, p. 128-135Article in journal (Refereed)
    Abstract [en]

    The polychaete Ophryotrocha puerilis is a male-to-female sex-changer, whereas O. labronica has separate sexes throughout life. In other respects the two species are remarkably similar: they occur in the same habitat, they look the same, they eat the same things, and in some O. labronica populations sex-changers can actually be found. The size-advantage hypothesis predicts that in O. puerilis males should not benefit reproductively from a size increase as much as males in O. labronica: hence O. puerilis but not O. labronica males should change to the female sex at a certain size. I experimentally compared reproductive success at different body sizes between the two species. In isolated male-female pairs reproductive rate increased significantly with female body size but not with male body size, and this pattern was the same in both species. Hence male fecundity per se cannot account for the difference in reproductive type between the two species. In other experiments I investigated if larger males gained access to more females because they were superior competitors for mates or were preferred by females, compared to small males. In O. puerilis the combined effect of these two factors conferred no size advantage to the males, whereas in O. labronica larger males acquired more females than did smaller males. Hence interactions among males and females, in accordance with the size-advantage hypothesis, can explain why sex change is maintained in O. puerilis, and why separate sexes are maintained in O. labronica.

  • 24.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Why are sexually selected weapons almost absent in females?2013In: Current Zoology, ISSN 1674-5507, Vol. 59, no 4, p. 564-568Article in journal (Refereed)
    Abstract [en]

    In sex role reversed species, predominantly females evolve sexually selected traits, such as ornaments and/or weapons. Female ornaments are common and their function well documented in many species, whether sex role reversed or not. However, sexually selected female weapons seem totally absent except for small wing spurs in three jacana species, present in both males and females. This poor female weaponry is in sharp contrast to the situation in species with conventional sex roles: males commonly have evolved sexually selected weapons as well as ornaments. At the same time, females in many taxa have naturally selected weapons, used in competition over resources or in predator defence. Why are sexually selected weapons then so rare, almost absent, in females? Here I briefly review weaponry in females and the function of these weapons, conclude that the near absence of sexually selected weapons begs an explanation, and suggest that costs of sexually selected weapons may exceed costs of ornaments. Females are more constrained when evolving sexually selected traits compared to males, at least compared to those males that do not provide direct benefits, as trait costs reduce a female’s fecundity. I suggest that this constraining trade-off between trait and fecundity restricts females to evolve ornaments but rarely weapons. The same may apply to paternally investing males. Whether sexually selected weapons actually are more costly than sexually selected ornaments remains to be investigated.

  • 25.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Bengtsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Biotic and abiotic factors determining the distribution of two prawn species: Palaemon adspersus and P. squilla1981In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 49, no 3, p. 300-304Article in journal (Refereed)
    Abstract [en]

    The reasons behind the absence of the prawn Palaemon adspersus and the presence of P. squilla in rockpools and on bare sand bottoms were studied. Some maximal abundances in different habitats are given. Introduction experiments into natural and artificial rockpools and measurements of tolerance towards low oxygen levels showed that nocturnal hypoxia excluded P. adspersus which was significantly more sensitive to oxygen depletion. Respiration rates measured by the closed-bottle method showed no interspecific difference. On bare sand bottoms P. aspersus was probably excluded by predators, since predator exclusion experiments in cages and predator inclusion experiments in containers showed that P. adaspersus was more vulnerable to predation than P. squilla.The costs for being able to cope with a wide array of habitat in P. squilla are probably balanced by the benefits of access to habitats such as intertidal rockpools, very shallow bottoms and deeper sand bottoms. Tolerance towards abiotic factors extends its habitat range upwards into shallower waters, and tolerance towards biotic factors, i.e. predation, extends it downwards.

  • 26.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Bisazza, Angelo
    Pilastro, Andrea
    Armaments and ornaments: An evolutionary explanation of traits of dual utility1996In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 58, no 4, p. 385-399Article in journal (Refereed)
    Abstract [en]

    Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual function, we propose that they commonly arise through intrasexual selection processes and serve as honest signals to other males regarding fighting ability or dominance. Faking these traits, here called armaments, (i.e. weapons and status badges) is difficult, as they are constantly put to trial in male-male contests. Females that subsequently utilize them as indicators of male phenotypic quality when selecting a partner will benefit by acquiring males of higher quality to father their offspring. Thus, evolution of armaments through male-male competition is seen as a usually initiating process, whereas female choice later may assume a role as an additional selective factor. The reverse, that males use information from traits evolved through female choice, is, however, also possible. The traditional view of independently evolved and temporarily unordered intra- and intersexual selection processes fails to explain dual trait functions. Moreover, our model may more satisfyingly than traditional ones explain how trait honesty and trait genetic variance are maintained: theoretical and empirical evidence suggests that such honesty and variation are more easily maintained under male-male competition than under female choice. (C) 1996 The Linnean Society of London

  • 27.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Lagercrantz, Ulf
    Genetic differentiation in populations of two Palaemon prawn species at the Atlantic east coast: does gene flow prevent local adaptation?1983In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 77, no 1, p. 49-57Article in journal (Refereed)
    Abstract [en]

    Two Palaemon prawn species, P. adspersus Rathke and P. squilla (L.), occur along the European Atlantic coast. In areas heavily affected by tides (Netherlands and France), one species, P. squilla, inhabits the intertidal zone, and P. adspersus is found subtidally in the Zostera marina meadows. In areas with small tidal ranges (Sweden) both species occur in the Z. marina zone, and here the body size of P. squilla is reduced, something that in turn reduces reproductive output in this species. Is adaptive improvement in non-tidal P. squilla populations prevented by too extensive gene flow from tidal areas? To wanswer this, genetic differentiation was studied by horizontal starch gel electrophoresis. Each of the two species was sampled at five sites along the European Atlantic coast. Twenty-two enzymes representing 25 loci were scored. Significant genetic heterogeneity between sites was found in both species. Thus the extensive gene flow hypothesis was not supported by the results, and non-tidal populations ought to have the possibility to adapt to local conditions.

  • 28.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Magnhagen, Carin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Bisazza, Angelo
    König, Barbara
    Huntingford, Felicity
    Female-female competition over reproduction1993In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 4, no 2, p. 184-187Article in journal (Refereed)
  • 29.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    An intimidating ornament in a female pipefish2009In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 20, no 1, p. 54-59Article in journal (Refereed)
    Abstract [en]

    A sexually selected signal may serve a dual function being both attractive to mates and deterring rivals. Presently, there are few unambiguous demonstrations of an ornament functioning in both a mate choice and mate competition context and none regarding female ornaments. We have shown earlier that a temporary ornament, a striped pattern, in a sex-role reversed female pipefish, Syngnathus typhle, attracts males. Here we show that this ornament also intimidates rival females: in one experiment a male could interact with either 1 or 2 females. Latency until copulation was longer when 2, rather than 1, females were present. Moreover, when 2 females were present, competition lasted longer and time until mating took place increased when females displayed their ornaments more equally. In another experiment, a focal female could see 1 stimulus female and 1 stimulus male, the latter 2 being unaware of each other. The ornament of the stimulus female was manipulated, either strengthened by being painted black or left unaltered by being sham-painted. As a result, focal females experiencing black-painted stimulus females decreased courtship as well as competitive activities compared with focal females seeing sham-painted females. Moreover, focal females seeing black-painted females displayed less of their own ornament compared with controls. This decrease was due to a decrease in display toward males rather than to stimulus females. Thus, this female ornament indeed has a dual function, attracting mates and deterring rivals. In addition, the social costs invoked by this intimidating effect on rivals may help to maintain signal honesty.

  • 30.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Male limitation of female reproductive success in a pipefish  : effects of body-size differences1990In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 27, no 2, p. 129-133Article in journal (Refereed)
    Abstract [en]

     In the pipefish Syngnathus typhle, a species with exclusive male parental care, males limit female reproductive success because of their limited brood pouch space and long pregnancy. Sexual size dimorphism is absent in these 1-year-old animals but increases with age so that older females are larger than similarly aged males. Because fecundity is related to size in both sexes and increases more rapidly with body size in females than in males, the difference in growth increases female fecundity more, relative to male fecundity, as the fish get older. We therefore predicted that male limitation of female reproductive success is even more severe when all age classes are considered. To measure a female's maximum reproductive rate, she was provided with three males. Small 1-year-old females produced as many eggs, or produced eggs at the same rate, as a male of similar size could care for. Small females filled on average 1.06 males within the time span of one male pregnancy and actually produced on average 10 eggs fewer than needed to fill a similarly sized male. Large 2-year-old females, in contrast, produced on average a surplus of 149 eggs and filled 2.7 similarly sized males within the course of one pregnancy. The difference between females of the two size classes was highly significant. Males prefer to mate with larger females if given a choice. In nature sex ratios are equal, and males limit female reproductive success in the whole population. Therefore, small females are more severely constrained by mate availability than are larger females because males choose to mate with larger females.

  • 31.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Male pipefish prefer dominant over attractive females.2001In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 12, no 4, p. 402-406Article in journal (Refereed)
    Abstract [en]

    Animals may obtain information guiding their choice between potential partners from observing competitive interactions and displays between them, or from displays directed at the choosing individual. In the sex-role reversed pipefish Syngnathus typhle females display a temporary ornament (a color pattern) to other females as well as to males. We have previously shown that display of female ornaments per se is attractive to males. Here we show that information from competitive displays can override such direct attraction displays as signals in the partner choice process. In a mate choice experiment, an enclosed male could choose between two females. On the first experimental day, females could interact freely, while on the second day they were isolated from each other. When female-female competition was allowed, the ornament display was directed more to the other female than to the male: Time competing, rather than time courting the male, correlated with ornament display duration. However, ornament display under competition and ornament display in the absence of competition did not correlate significantly. In fact, females competing more intensively on day one displayed the ornament less on day two. Furthermore, the ornament display during the first, but not the second, day predicted male mate choice on the second day. Thus, males remembered previous information from competitive displays and used it rather than immediate information from displays in the absence of female-female competition. We suggest that competitive displays more reliably signal female quality as compared to noncompetitive ones, and that males benefit from mating with dominant females.

  • 32.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Male pipefish prefer ornamented females2001In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 61, no 2, p. 345-350Article in journal (Refereed)
    Abstract [en]

    In the sex-role reversed pipefish Syngnathus typhle females compete for access to males and males are choosy. Females display a temporary ornament, a striped pattern. We show here for the first time in a sex role-reversed species that ornament display predicts how much time a female will devote to competitive behaviours, that males prefer ornamented females over nonornamented ones, and that the ornament is attractive even when female behaviour is held constant. This was demonstrated in an experiment with a male choosing between two females, first with the females separated and then with interactions allowed between the females as well as with the male. Females displaying the ornament for a longer time enjoyed a higher mating success then those displaying the ornament more briefly. Ornament display in the absence of intrasexual competition also predicted the amount of time that females subsequently spent competing. Thus, females initially displaying an attractive trait were also subsequently competing for longer. Furthermore, we manipulated the ornament by painting females and controlled their behaviour by sedating them and moving them in a dance-like fashion by a motor. This experiment showed that males preferred ornamented females, even when female behaviour was standardized. Thus, ornament display accurately predicted the duration of female–female competition and mating success, and was used as a signal by males in their choice of mates.

  • 33.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Reproductive costs in the prawn Palaemon adspersus: effects on growth and predator vulnerability1986In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 46, no 3, p. 349-354Article in journal (Refereed)
  • 34.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Selective males and ardent females in pipefishes1993In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 32, no 5, p. 331-336Article in journal (Refereed)
    Abstract [en]

    In the pipefishes Syngnathus typhle and Nerophis ophidion, males have been shown to limit female reproductive rate, and females to compete for access to males. Hence, these species fit the criteria for sex-role reversal. Males brood the eggs and provide the offspring with nutrients, oxygen and an osmoregulated environment. Moreover, in S. typhle both sexes prefer a larger mate when given a choice. Sexual selection theory predicts that males should be more '' choosy '' than females, and that was experimentally demonstrated in this study. We predicted that S. typhle males should be less eager to copulate than S. typhle females with an unattractive (i.e. small) mate. We measured eagerness as the time from the start of the experiment until copulation occurred. Males with unattractive partners took significantly longer to copulate than females with unattractive partners. Moreover, females invariably initiated the courtship dance, and resumed it quicker after copulation than did the males, again suggesting ''reproductive hesitation'' in males. Neither male nor female size per se was correlated with time until copulation. In N. ophidion, where we have previously shown that males prefer larger to smaller females, we found that females did not select males with regard to size. Our results are consistent both with earlier findings (males limit female reproduction and females compete for males) and with operational sex ratios in nature: in seven annual field samples in June, the numbers of S. typhle females with ripe eggs always significantly exceeded numbers of receptive males. Hence, the potential cost of being choosy in terms of lost matings is much higher in females than in males. In conclusion, S. typhle females were somewhat choosy, but less so than males, whereas N. ophidion females were not choosy at all.

  • 35.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Sex-role reversal in pipefish2003In: Advances in the Study of Behavior, ISSN 0065-3454, E-ISSN 2162-8823, Vol. 32, p. 131-167Article in journal (Refereed)
  • 36.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Bernet, Patricia
    Ornamentation predicts reproductive success in female pipefish1997In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 40, no 3, p. 145-150Article in journal (Refereed)
    Abstract [en]

    In the sex-role reversed pipefish Syngnathus typhle females compete for access to males and males are choosy. Females develop a temporary ornament when competing over mates with other females and when performing nuptial dances with males. This ornament is an amplification of the normal striped pattern in these fishes. We here show experimentally that (1) the contrast of this normal pattern forecasts the extent to which the ornament is shown, (2) contrast and ornamentation honestly signal female quality (egg numbers), (3) contrast and ornamentation accurately predict female mating success, (4) contrast is a phenotypically plastic trait specifically exaggerated under situations of female - female competition, and (5) neither contrast nor ornament. are energetically expensive to the females (i.e., they are independent of short-term nutritional status). Hence, as predicted in sex-role reversed species, ornament design is constrained by costs to female fecundity: an energetically demanding ornament would impair on a female's ability to produce eggs. The type of ornament described here is the expected one, costly for reasons other than being energetically expensive to produce.

  • 37.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Robinson-Wohlrath, Sarah
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Food or sex: males and females in a sex role reversed pipefish have different interests2006In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 60, no 2, p. 281-287Article in journal (Refereed)
    Abstract [en]

    In a sex role reversed pipefish, Syngnathus typhle, we found that basic life history allocations were directly influenced by sexual selection. We investigated time allocation to foraging and mating, respectively, in a choice experiment, giving males and females, of small or large body size, a choice between food and a potential partner. We found that males were more interested in foraging than mating, i.e., were more frequently observed in front of the food than in front of the partner, whereas females were more interested in the potential partner. This reflects sexual selection operating differently on the two sexes, as males and females are relatively similar in other life history traits, such as growth, mortality, age of maturity, dispersal, and parental expenditure. Moreover, large individuals allocated more time to mating activities, small to feeding. Individuals more interested in mating compared to food were subsequently more critical when given a choice between a large (high-quality) and a small (low-quality) partner, whereas individuals more interested in food were not selective. These findings are consistent with our predictions: sex-role reversed males can be relatively sure of achieving one or more matings, and should allocate more time to feeding and, hence, to parental investment, growth and/or future reproduction. Females, on the other hand, have more uncertain mating prospects and should allocate time to imminent reproductive activities, thereby foregoing other life history traits such as growth and future egg production. By this, they also sacrifice future fecundity and attractiveness.

  • 38.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Mate choice, fecundity and sexual dimorphism in two pipefish species (Syngnathidae)1986In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 19, no 4, p. 301-307Article in journal (Refereed)
    Abstract [en]

    In order to understand the causes of sexual dimorphism, mate choice and size-related fecundity were studied in two pipefish species, Syngnathus typhle and Nerophis ophidion. Sexual dimorphism is more pronounced in N. ophidion; females are larger, have sexual colourings, and are more active during courtship. In S. typhle the sexes are alike in all these respects. Males brood their offspring in both species. In N. ophidion fecundity was positively correlated with both body size and the amount of sexual colouring in females. In males no correlation between body size and fecundity, or between body size and embryo size existed. Predictably, in mate choice experiments with equal-sized females, males chose females with more extensive sexual colourings. We explain sexual dimorphism in this species as a consequence of both natural selection (fecundity increases with size in females but not in males) and sexual selection (males prefer larger females). We argue that sexual size dimorphism did not evolve by selection minimizing overlap in food niches between the sexes, because food production is high in the Zostera beds where the fishes live, and no size dimorphism was found in the sympatrically occurring S. typhle. Furthermore, in N. ophidion dimorphism is not greater in a particular mouth character than in overall body size. In S. typhle egg size and the average number of eggs transferred per spawning were positively correlated with female body size. Apparently more energy per offspring was provided by larger males than by smaller males, and larger males also carried more offspring. As predicted, large mates were preferred by both sexes in mate choice experiments. This is explicable in terms of both natural selection (fecundity increases with size in both sexes) and sexual selection (both sexes prefer large mates). As a consequence of selection acting in the same direction in both sexes, sexual dimorphism is absent in S. typhle.

  • 39.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Multiple matings and paternal brood care in the pipefish Syngnathus typhle1988In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 51, no 2, p. 184-188Article in journal (Refereed)
  • 40.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reproductive success of females limited by males in two pipefish species1989In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 133, no 4, p. 506-516Article in journal (Refereed)
    Abstract [en]

    We investigate whether males limit the reproductive success of females in the two pipefish species Syngnathus typhle and Nerophis ophidion. Syngnathus typhle is sexually monomorphic, and courtship behavior does not differ between the sexes. In N. ophidion, on the contrary, females are larger, more colorful, and more active during courtship, possessing appearance-enlarging skin folds. In both species, males brood the offspring on their bodies, one internally and one externally. Males do not invest more energy in reproduction than do females, and in the sexually dimorphic species, males invest even less than females do. Natural sex ratios are equal in both species. Experimentally, we provided each female with an excess of males (i.e., three), in order to measure a female's maximal reproductive rate, and found that females of both species produced more eggs, or produced them at a faster rate, than naturally available males could care for. Within the time span of one male pregnancy, S. typhle females filled an average of 1.9 males and N. ophidion an average of 1.8 males; both numbers are significantly more than one (which is the average mate availability in natural populations). Measured in another way, during one male pregnancy, S. typhle and N. ophidion females both produced 41% more eggs than needed to fill a male, significantly more than no egg surplus in both species. Therefore, brood space and the rate of embryonic development limit female reproduction in these species. There was no significant difference between the species, however. Syngnathus typhle males might be expected to be less limiting than N. ophidion males, but sexual size dimorphism may be absent in S. typhle because, by contrast with N. ophidion, larger males enjoy greater reproductive success. Directional selection for increased male size may decrease sexual size dimorphism in S. typhle. At any rate, the limitation of the reproductive success of one sex by the other seems to be a necessary but not sufficient prerequisite for the evolution of sexual dimorphism and "sex roles."

  • 41.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reversed sex-roles and parental energy investment in zygotes of two pipefish (Syngnathidae) species1986In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 29, no 3, p. 209-215Article in journal (Refereed)
  • 42.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sundin, Josefin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Rosenqvist, Gunilla
    Norwegian University of Science and Technology.
    Baltic pipefish females need twice as many males as they get2017In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 28, no 3, p. 827-832Article in journal (Refereed)
    Abstract [en]

    Sex role reversal in 2 pipefish species, Syngnathus typhle and Nerophis ophidion, is potentially explained by females reproducing twice as fast as males. Moreover, in oceanic populations from the Swedish west coast, females compete for males with males pre- ferring to mate with larger females. However, in a brackish Baltic population of S. typhle, males do not prefer larger mates, whereas choosiness remains in the local N. ophidion population. We explore whether this absence of male choice in brackish S. typhle can be explained by males and females having more similar potential reproductive rates here, whereas the sex difference may remain in the local N. ophidion population. Contrary to our expectations, in both species, females out-reproduced males by a factor of more than 2, just as in the oceanic populations. We measured this experimentally as the number of males a female potentially could fill with eggs within the time span of 1 male pregnancy, in relation to males available in nature. Thus, we conclude that sexual selection on females is as strong in brackish as in oceanic populations of both species but that targets of selection via male choice are shifted to traits other than body size in S. typhle. Hence, costs and benefits of choice are probably more important than potential reproductive rates to understand mate choice. We suggest that it may be misleading to use targets of sexual selection, such as choice for large body size, as an indicator of the strength of sexual selection. 

  • 43.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Widemo, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Sex-role reversal revisited: choosy females and ornamented, competitive males in a pipefish2005In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 16, no 3, p. 649-655Article in journal (Refereed)
    Abstract [en]

    In the pipefish Syngnathus typhle sex roles are reversed, that is, females compete more intensely than males over mates. However, competition over mates among individuals of one sex does not necessarily prevent members of that same sex from being choosy, and choosiness in the other sex does not prevent competition within it. In an experiment we allowed a female pipefish to choose freely between two males, after which we released the males and let the three interact. Comparisons with earlier results show that both sexes courted partners and competed with consexuals. However, females courted more often than did males, and courtship was more frequent in treatments involving large individuals than in treatments with small individuals. Males competed among themselves for access to mates but for a shorter duration than females in the same situation. Males displayed an ornament towards females but not to males during mating competition. Females, however, used their ornament in both contexts. Females did not always mate with the male of their previously made choice, which we interpret as females being constrained by male-male competition, male motivation to mate, or both. Thus, in this sex-role reversed species, mate choice in the more competitive sex may be circumvented and even overruled by mate competition and mating willingness in the least competitive sex. Hence, sex roles should not be considered as sexes being either choosy or competitive but rather that males and females may exhibit different combinations of choice and competition.

  • 44.
    Bernet, Patricia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Female-female competition affects female ornamentation in the sex-role reversed pipefish Syngnathus typhle1998In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 135, no 5, p. 535-550Article in journal (Refereed)
    Abstract [en]

    1. In the sex role reversed pipefish Syngnathus typhle females compete for males, and males are more choosy than females. Before mating. females display a temporary sexual ornament in the form of a lateral zigzag pattern. which is an amplification of their permanent colour pattern. 2. In experiments males showed no significant preferences for permanently contrast-rich females, nor for females matching closely with the background. 3. Females in physical contact with a male could potentially develop the ornament, but under female-female competition females were more likely to display it than otherwise. 4. The ornament accurately predicted female mating success. More ornamented females displayed more actively towards males and were found closer to males than were non-ornamented females.

  • 45. Billing, Anna M.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    No terminal investment in pipefish males: Only young males exhibit risk-prone courtship behavior2007In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 18, no 3, p. 535-540Article in journal (Refereed)
    Abstract [en]

    Animals are expected to trade-off current and future reproduction in order to maximize lifetime reproductive success. Old individuals may accept higher risks during courtship and mate choice as their residual reproductive value (RRV) diminishes (the terminal investment hypothesis). Alternatively, young individuals may be forced to take higher risks during courtship to compensate for their lower competitiveness and/or attractiveness (the compensation hypothesis). In this study, we used the sex-role reversed pipefish Syngnathus typhle to test how mate choice and courtship behavior of males with different RRV were affected by an increase in predation risk. Males of different ages were given the opportunity to court and choose between 2 partners. In half of the trials, a predator was present in a separate aquarium. We found no support for the terminal investment hypothesis: no difference in response to the increased predation risk by males of different ages was evident. In agreement with the compensation hypothesis, young males invested more in courtship behavior compared with older males. In addition, in the absence of a predator, we found that a high female activity was important for male mate choice decisions. During increased predation risk, this relationship was, however, reversed and males preferred less active, and thus less conspicuous, partners. This suggests that both female activity and size are important factors for male mating decisions in this species and that these decisions mainly are affected by predation risk and advantages in mate acquisition.

  • 46. Borg, Åsa A.
    et al.
    Åsmul, Tommy
    Bolstad, Geir H.
    Viken, Åslaug
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Rosenqvist, Gunilla
    Interactions Among Female Guppies (Poecilia reticulata) Affect Growth and Reproduction2012In: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 118, no 8, p. 752-765Article in journal (Refereed)
    Abstract [en]

    Competition among females over resources may have consequences for their resource budgets and thereby the resource allocation between growth and reproduction. In addition, the consequences of femalefemale interactions may differ for dominant and subordinate individuals, with the dominant ones being at an advantage. In this study, we investigated the consequences of femalefemale competition in guppies by manipulating the competitive environment of females. We found that large guppy females dominated smaller females and that interactions between females likely are costly because females exposed to competition grew less. These females compensated by growing at a higher rate when no longer subjected to competition. The higher growth rate might in turn be the cause of the reduced reproductive effort in the more competitive treatments. Furthermore, interactions were more costly for females when they were in the subordinate role than in the dominant role, because the reduction in growth and reproductive effort was highest in females exposed to larger competitors. Whether there was a differential allocation of resources into growth and reproduction depending on dominance status needs further investigation. However, in general, smaller females had a higher growth rate than larger females, independent of competitive level. We also found a negative relationship between reproduction and growth in all treatments, indicating a cost of reproduction.

  • 47.
    Cunha, M
    et al.
    Univ Porto, Ctr Invest Biodiversidade & Recursos Genet, CIBIO InBIO, Vairao, Portugal.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Mendes, S
    Univ Porto, Ctr Invest Biodiversidade & Recursos Genet, CIBIO InBIO, Vairao, Portugal.
    Monteiro, N
    Univ Porto, Ctr Invest Biodiversidade & Recursos Genet, CIBIO InBIO, Vairao, Portugal; Univ Fernando Pessoa, Fac Ciencias Saude, CEBIMED, Porto, Portugal.
    The ‘Woman in Red’ effect: pipefish males curb pregnancies at the sight of an attractive female2018In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 285, no 1885, article id 20181335Article in journal (Refereed)
    Abstract [en]

    In an old Gene Wilder movie, an attractive woman dressed in red devastated a man’s current relationship. We have found a similar ‘Woman in Red’ effect in pipefish, a group of fish where pregnancy occurs in males. We tested for the existence of pregnancy blocks in pregnant male black-striped pipefish (Syngnathus abaster). We allowed pregnant males to see females that were larger and even more attractive than their original high-quality mates and monitored the survival and growth of developing offspring. After exposure to these extremely attractive females, males produced smaller offspring in more heterogeneous broods and showed a higher rate of spontaneous offspring abortion. Although we did not observe a full pregnancy block, our results show that males are able to reduce investment in current broods when faced with prospects of a more successful future reproduction with a potentially better mate. This ‘Woman in Red’ life-history trade-off between present and future reproduction has similarities to the Bruce effect, and our study represents, to our knowledge, the first documentation of such a phenomenon outside mammals.

  • 48. Cunha, Mario
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Monteiro, Nuno
    The intrinsically dynamic nature of mating patterns and sexual selection2015In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 98, no 4, p. 1047-1058Article in journal (Refereed)
    Abstract [en]

    Selection processes are influenced by both biotic and abiotic variables, most of which seasonally fluctuate. Therefore, selection may also vary temporally. Specifically, sexual selection, an integral component of natural selection, will inevitably exhibit temporal variation but the scale at which these changes occur are still not well understood. In this study, performed on a wild population of the sex-role reversed black striped pipefish Syngnathus abaster (Risso, 1827), we contrast variables such as male reproductive success, mating success, female investment, mate choice and operational sex ratio between two periods, either near the onset or end of the breeding season. Sexual selection is stronger early in the breeding season. Male reproductive and mating success are significantly affected by male size during the onset of the breeding season but not during the end. Moreover, we found that larger females reproduce mainly during the onset while smaller females had increased chances of reproducing towards the end. As our sampling was performed in two consecutive years, it could be argued that our results stem primarily from between-year variation. Nevertheless, variation in demographic parameters from the onset to the end of the breeding season is similar to that observed in past sampling events. Hence, we suggest that the change in mating patterns within the breeding season derives from seasonal fluctuations in several abiotic (e.g., temperature) and biotic variables (e.g., operational sex ratio), rendering the expression of selective forces, such as sexual selection, inherently dynamic.

  • 49. Cunha, Mário
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Alves, T
    Monteiro, Nuno
    Reduced cannibalism during male pregnancy2016In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 153, no 1, p. 91-106Article in journal (Refereed)
    Abstract [en]

    Cannibalism provides energetic benefits but is also potentially costly, especially when directed towards kin. Since fitness costs increase with time and energy invested in offspring, cannibalism should be infrequent when parental investment is high. Thus, filial cannibalism in male syngnathids, a group known for the occurrence of male pregnancy, should be rare. Using the pipefish (Syngnathus abaster) we aimed to investigate whether cannibalism does occur in both sexes and how it is affected by reproductive and nutritional states. Although rare, we witnessed cannibalism both in the wild and in the laboratory. Unlike non-pregnant males and females, pregnant and postpartum males largely refrained from cannibalising juveniles. Reproducing males decreased their feeding activity, thus rendering cannibalism, towards kin or non-kin, less likely to occur. However, if not continuously fed, all pipefish adopted a cannibal strategy, revealing that sex and life history stages influenced the ratio between the benefits and costs of cannibalism.

  • 50. Cunha, Mário
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Monteiro, Nuno
    Female ornaments signal own and offspring quality in a sex-role-reversed fish with extreme male parental care2017In: Marine Ecolocy, ISSN 0173-9565, E-ISSN 1439-0485, Vol. 38, article id e12461Article in journal (Refereed)
    Abstract [en]

    Although female ornaments have been described in many taxa, the full spectrum of information conveyed by such traits together with the potential male fitness benefits are far from fully understood. Here, we used a sex-role-reversed species, the black-striped pipefish, Syngnathus abaster, where females are the ornamented sex and intensively compete for mates who present an extreme form of paternal care (male pregnancy). We investigated what information is conveyed by female traits and if males are using it during mate choice. We further assessed which traits would reflect offspring quality at birth. We found that although body length generally portrays information on female reproductive potential (gonadosomatic index and oocyte diameter),it does so indirectly. Different aspects of the female traits, such as stripe width and trunk broadness, were found to be better direct indicators. When size is kept constant, males prefer females with wider stripes. Moreover, stripe coloration was found to reflect offspring quality as darker-striped females produced larger newborns. Our observations suggest that in a species with exclusive paternal care, independently from the male’s direct investment in reproduction, female contribution decisively impacts male fitness. Thus, at least in sex-role-reversed species such as the black striped pipefish, female ornaments can be selected in an analogous way to those of males in species with conventional sex roles (i.e. by mate choice).

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