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Stochastic Modeling of Mating Systems and their Effect on Population Dynamics and Genetics
Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, Department of Biology.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
2011.
Series
Doctoral theses at NTNU, ISSN 1503-8181 ; 2011:94
Identifiers
URN: urn:nbn:no:ntnu:diva-12706ISBN: 978-82-471-2719-3 (printed ver.)ISBN: 978-82-471-2720-9 (electronic ver.)OAI: oai:DiVA.org:ntnu-12706DiVA: diva2:421741
Public defence
2011-04-01, 00:00
Available from: 2011-06-09 Created: 2011-06-08 Last updated: 2011-06-09Bibliographically approved
List of papers
1. Understanding mating systems: A mathematical model of the pair formation process
Open this publication in new window or tab >>Understanding mating systems: A mathematical model of the pair formation process
2008 (English)In: Theoretical Population Biology, ISSN 0040-5809, E-ISSN 1096-0325, Vol. 73, no 1, 112-124 p.Article in journal (Refereed) Published
Abstract [en]

Mechanisms generating inequalities among males in reproductive success are key to understanding the evolutionary significance of sexual selection. This paper develops a stochastic model to quantitatively describe and analyze mating systems on a continuous scale from strict monogamy to extreme polygyny. The variance in male mating success is shown to increase with increased differences among males, with decreased interdependence of mating events, with increased population size, and with an increased number of females per male. The latter condition decreases the opportunity for sexual selection. It is found that different combinations of mating system characteristics can lead to the same variance in male mating success, although the distribution differs. This emphasizes the importance of using a model of this type to study mating systems, rather than relying solely on the variance in reproductive success as a descriptor of different systems. (C) 2007 Elsevier Inc. All rights reserved.

Keyword
mating systems, pair formation, reproductive skew, reproductive success, sexual selection, stochastic model
Identifiers
urn:nbn:no:ntnu:diva-12701 (URN)10.1016/j.tpb.2007.09.003 (DOI)000253339100009 ()
Note
The article is reprinted with kind permission from Elsevier, sciencedirect.comAvailable from: 2011-06-08 Created: 2011-06-08 Last updated: 2011-06-09Bibliographically approved
2. Demographic Stochasticity, Allee Effects, and Extinction: The Influence of Mating System and Sex Ratio
Open this publication in new window or tab >>Demographic Stochasticity, Allee Effects, and Extinction: The Influence of Mating System and Sex Ratio
2011 (English)In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 177, no 3, 301-313 p.Article in journal (Refereed) Published
Abstract [en]

Demographic stochasticity has a substantial influence on the growth of small populations and consequently on their extinction risk. Mating system is one of several population characteristics that may affect this. We use a stochastic pair-formation model to investigate the combined effects of mating system, sex ratio, and population size on demographic stochasticity and thus on extinction risk. Our model is designed to accommodate a continuous range of mating systems and sex ratios as well as several levels of stochasticity. We show that it is not mating system alone but combinations of mating system and sex ratio that are important in shaping the stochastic dynamics of populations. Specifically, polygyny has the potential to give a high demographic variance and to lower the stochastic population growth rate substantially, thus also shortening the time to extinction, but the outcome is highly dependent on the sex ratio. In addition, population size is shown to be important. We find a stochastic Allee effect that is amplified by polygyny. Our results demonstrate that both mating system and sex ratio must be considered in conservation planning and that appreciating the role of stochasticity is key to understanding their effects.

Keyword
Allee effect, demographic stochasticity, extinction, mating systems, population dynamics, sex ratio
Identifiers
urn:nbn:no:ntnu:diva-12700 (URN)10.1086/658344 (DOI)000287996000003 ()
Available from: 2011-06-08 Created: 2011-06-08 Last updated: 2011-06-09Bibliographically approved
3. FIXATION OF SLIGHTLY BENEFICIAL MUTATIONS: EFFECTS OF LIFE HISTORY
Open this publication in new window or tab >>FIXATION OF SLIGHTLY BENEFICIAL MUTATIONS: EFFECTS OF LIFE HISTORY
2010 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 4, 1063-1075 p.Article in journal (Refereed) Published
Abstract [en]

Recent studies of rates of evolution have revealed large systematic differences among organisms with different life histories, both within and among taxa. Here, we consider how life history may affect the rate of evolution via its influence on the fixation probability of slightly beneficial mutations. Our approach is based on diffusion modeling for a finite, stage-structured population with stochastic population dynamics. The results, which are verified by computer simulations, demonstrate that even with complex population structure just two demographic parameters are sufficient to give an accurate approximation of the fixation probability of a slightly beneficial mutation. These are the reproductive value of the stage in which the mutation first occurs and the demographic variance of the population. The demographic variance also determines what influence population size has on the fixation probability. This model represents a substantial generalization of earlier models, covering a large range of life histories.

Keyword
Age structure, demographic stochasticity, fixation probability, life history evolution, population genetics, reproductive value
Identifiers
urn:nbn:no:ntnu:diva-11837 (URN)10.1111/j.1558-5646.2009.00868.x (DOI)000276035000016 ()
Available from: 2011-01-18 Created: 2011-01-18 Last updated: 2012-07-04Bibliographically approved
4. The influence of persistent individual differences and age at maturity on effective population size.
Open this publication in new window or tab >>The influence of persistent individual differences and age at maturity on effective population size.
2011 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954Article in journal (Refereed) Epub ahead of print
Abstract [en]

Ratios of effective populations size, N(e), to census population size, N, are used as a measure of genetic drift in populations. Several life-history parameters have been shown to affect these ratios, including mating system and age at sexual maturation. Using a stochastic matrix model, we examine how different levels of persistent individual differences in mating success among males may affect N(e)/N, and how this relates to generation time. Individual differences of this type are shown to cause a lower N(e)/N ratio than would be expected when mating is independent among seasons. Examining the way in which age at maturity affects N(e)/N, we find that both the direction and magnitude of the effect depends on the survival rate of juveniles in the population. In particular, when maturation is delayed, lowered juvenile survival causes higher levels of genetic drift. In addition, predicted shifts in N(e)/N with changing age at maturity are shown to be dependent on which of the commonly used definitions of census population size, N, is employed. Our results demonstrate that patterns of mating success, as well as juvenile survival probabilities, have substantial effects on rates of genetic drift.

Identifiers
urn:nbn:no:ntnu:diva-12702 (URN)10.1098/rspb.2011.0283 (DOI)21436183 (PubMedID)
Available from: 2011-06-08 Created: 2011-06-08 Last updated: 2011-06-09Bibliographically approved

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