Ecology and Evolution, Stony Brook University
April 16, 2016 16, Atrium Ballroom A/B
Lower basal metabolic rates (BMR) in lemurs or strepsirrhines, compared to other primates, are thought to constrain life history traits. These differences are used to support hypotheses of life history traits as adaptations to highly seasonal temperatures and/or resources (the Energy Conservation Hypothesis, ECH). Despite past tests of the effect of the ECH on life history traits, its basis in differences in BMR has never been studied in phylogenetic context.
Here, I use phylogenetic regressions and ANCOVAs, with body mass as a covariate, to examine differences in BMR among 38 primate species. To test for the proposed adaptive nature of BMR (the ECH), I fitted Ornstein-Uhlenbeck models, grouping primates by inter-annual variation and seasonality of precipitation and temperature as proxies for environmental constraints.
There are no differences between BMRs of Strepsirrhines and Haplorhines, lemurs and Haplorhines, or lemurs and non-lemur Strepsirrhines (p>0.05). The aye-aye (Daubentonia madagascariensis) has a BMR higher than the 95% confidence intervals of the Strepsirrhine regression. Models of the adaptive landscape identify a shift in the rate of evolution along the D. madagascariensis branch and imply an adaptive optimum different from that of other primates. Environmental constraint models fail to explain variation in the BMR:BM relationship across primates.
Differences in BMR between lemurs or Strepsirrhines and other primates that have formed the bases for numerous life history hypotheses are non-existent, and the ECH does not explain variation across primates. Lemurs do not have low BMRs, but the highly encephalized D. madagascariensis is unique by Strepsirrhine standards.