Comparative support for the expensivetissue hypothesis: Big brains are correlatedwith smaller gut and greater parentalinvestment in Lake Tanganyika cichlids
2014 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 263, 33-38 p.Article in journal (Refereed) Published
The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirementsof encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerninghow energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment intoother costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly beentested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energeticlimitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test thesehypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of sharedancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, wefind that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Ourresults indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brainsize also in ectothermic vertebrates.
Place, publisher, year, edition, pages
2014. Vol. 263, 33-38 p.
Brain evolution, constraints, encephalization, phylogenetic comparative methods, the expensive tissue hypothesis, trade-offs.
IdentifiersURN: urn:nbn:se:liu:diva-112906DOI: 10.1111/evo.12556ISI: 000347462800015PubMedID: 25346264OAI: oai:DiVA.org:liu-112906DiVA: diva2:773664
The authors thank the staff of the Department of Fisheries of the Ministry of Agriculture and Cooperatives at Mpulungu, Zambia, for their cooperation during fieldwork, especially for collecting fishes from the deeper levels. They also thank H. Tanaka for collecting fish samples for us. This study was funded through the student exchange support program (scholarship for long-term study abroad) from the Japanese Student Services Organization (JASSO) to MT, the Zoologiska foundation to MT and AK, a Davis Expedition Fund grant, Helge Axelsson Johnson grant, and a Stiftelsen Hierta-Retzius stipendiefond grant to AH, the Austrian Science Fund (J 3304-B24) to AK, and a Swedish Research Council grant to NK. The authors have no conflict of interest to declare.2014-12-192014-12-192015-02-24