Energetic trade-offs between brain size and offspring production: Marsupials confirm a general mammalian pattern.
Recently, Weisbecker and Goswami presented the first comprehensive comparative analysis of brain size, metabolic rate, and development periods in marsupial mammals. In this paper, a strictly energetic perspective is applied to identify general mammalian correlates of brain size evolution. In both marsupials and placentals, the duration or intensity of maternal investment is a key correlate of relative brain size, but here I show that allomaternal energy subsidies may also play a role. In marsupials, an energetic constraint on brain size in adults is only revealed if we consider both metabolic and reproductive rates simultaneously, because a strong trade-off between encephalization and offspring production masks the positive correlation between basal metabolic rate and brain size in a bivariate comparison. In conclusion, starting from an energetic perspective is warranted to elucidate relations between ecology, social systems, life history, and brain size in all mammals.
Anthropological Institute and Museum, University of Zurich-Irchel, Switzerland. kisler@aim.uzh.ch
Karin
K
Isler
D000818:Animals; D001481:Basal Metabolism; D005075:Biological Evolution; D001921:Brain / Q000254:growth & development* / Q000378:metabolism*; D008394:Marsupialia / Q000254:growth & development* / Q000378:metabolism*; D009929:Organ Size; D012098:Reproduction