Does encephalization correlate with life history or metabolic rate in Carnivora?

Abstract

A recent analysis of brain size evolution reconstructed the plesiomorphic brain-body size allometry for the mammalian order Carnivora, providing an important reference frame for comparative analyses of encephalization (brain volume scaled to body mass). I performed phylogenetically corrected regressions to remove the effects of body mass, calculating correlations between residual values of encephalization with basal metabolic rate (BMR) and six life-history variables (gestation time, neonatal mass, weaning time, weaning mass, litter size, litters per year). No significant correlations were recovered between encephalization and any life-history variable or BMR, arguing against hypotheses relating encephalization to maternal energetic investment. However, after correcting for clade-specific adaptations, I recovered significant correlations for several variables, and further analysis revealed a conserved carnivoran reproductive strategy, linking degree of encephalization to the welldocumented mammalian life-history trade-off between neonatal mass and litter size. This strategy of fewer, larger offspring correlating with increased encephalization remains intact even after independent changes in encephalization allometries in the evolutionary history of this clade.

Endocranial Development in the Coyote (<b><i>Canis latrans</i></b>) and Gray Wolf (<b><i>Canis lupus</i></b>): A Computed Tomographic Study

“…Several authors have noted that encephalization, a measure of the difference between actual and expected brain size relative to body size, is higher in the coyote than the wolf [Bekoff, 1977;Kruska, 2005;Finarelli, 2008;Finarelli and Flynn, 2009]. This is consistent with our finding DOI: 10.1159/000487427…”

“…In addition, life history variables, such as length of the juve-DOI: 10.1159/000487427 nile period, age at sexual maturity, and total life span [Allman et al, 1993;Deaner et al, 2003;Barrickman et al, 2008;Finarelli, 2010;Gonzalez-Lagos et al, 2010;Charvet and Finlay, 2012;Workman et al, 2013, but see Barton and Capellini, 2011] are positively correlated with brain size after correcting for body size. Adult brain size also correlates with developmental duration [Passingham, 1985] and an evolutionary model linking developmental duration with brain size has been proposed [Finlay and Darlington, 1995;Workman et al, 2013] [review: Montgomery et al, 2016].…”

The Evolution of Relative Brain Size in Marsupials Is Energetically Constrained but Not Driven by Behavioral Complexity

“…Contrary to the relative inconclusiveness of selection-based research on mammals [Healy and Rowe, 2007], a large body of evidence shows that brain size is limited by maternal investment (the ability of females to provide sufficient nutrition for offspring brain growth) [Martin, 1981;Jones and MacLarnon, 2004;Martin et al, 2005;Finarelli, 2009a;Isler and Van Schaik, 2009;Shultz and Dunbar, 2010b;Weisbecker andGoswami, 2010, 2011;Barton and Capellini, 2011]. In addition, recent work on primates suggests that seasonality represents another energetic constraint on brain size [van Woerden et al, 2010[van Woerden et al, , 2012 possibly because the brain depends on reliable nutrition.…”

Rediscovering and Reviving Old Observations and Explanations of Metabolic Scaling in Living Systems

“…First, the concave upward scaling of basal metabolic rate in mammals is opposite of the scaling of brain mass, which is concave downward [34]. Second, several mammal studies have shown that basal metabolic rate is weakly or non-significantly correlated with brain size, after controlling for the effect of body size and other relevant factors (e.g., [199][200][201][202][203][204]). If a functional link exists between brain mass and metabolic rate, it may only occur in eutherian mammals, which have long periods of placental nutrient provisioning of offspring [202].…”