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Across mammals, encephalization and longevity show a strong correlation. It is not clear, however, whether these traits evolved in a correlated fashion within mammalian orders, or when they do, whether one trait drives changes in the other. Here, we compared independent and correlated evolutionary models to identify instances of correlated evolution within six mammalian orders. In cases of correlated evolution, we subsequently examined transition patterns between small/large relative brain size and short/long lifespan. In four mammalian orders, these traits evolved independently. This may reflect constraints related to energy allocation, predation avoidance tactics, and reproductive strategies. Within both primates and rodents, and their parent clade Euarchontoglires, we found evidence for correlated evolution. In primates, transition patterns suggest relatively larger brains likely facilitated the evolution of long lifespans. Because larger brains prolong development and reduce fertility rates, they may be compensated for with longer lifespans. Furthermore, encephalization may enable cognitively‐complex strategies that reduce extrinsic mortality. Rodents show an inverse pattern of correlated evolution, whereby long lifespans appear to have facilitated the evolution of relatively larger brains. This may be because longer lived organisms have more to gain from investment in encephalization. Together, our results provide evidence for the correlated evolution of encephalization and longevity, but only in some mammalian orders. [ABSTRACT FROM AUTHOR]

Long-tailed macaques (Macaca fascicularis) have a wide geographic distribution across mainland and insular Southeast Asia. The evolutionary history of long-tailed macaques has been examined extensively through comparison of phenotypic variation and by phylogenetic analyses of molecular genetic data. Nonetheless, the complex evolutionary history of M. fascicularis throughout Southeast Asia is not fully understood. For the present study, we performed a Bayesian phylogenetic analysis of M. fascicularis mitochondrial 12S/tRNA-val/16S sequences to examine the evolutionary relationships of the long-tailed macaques from Singapore. More generally, we hoped to gain a better understanding of the evolutionary history of long-tailed macaques throughout Southeast Asia. We used previously archived sequences in GenBank and new sequences from Singapore (n=34) and Bali, Indonesia (n=2) in a Bayesian phylogenetic framework to co-infer evolutionary histories and divergence dates. Our results revealed two large clades, one composed of haplotypes primarily from Sundaic islands populations, and the second primarily from continental populations. These two larger clades comprise four primary regional clades. All three haplotypes from Singapore form a well-supported subclade within a larger peninsular clade. A medianjoining network of haplotypes mirrored the results from the phylogenetic analyses. We found divergence dates that were largely consistent with previous studies using complete mitochondrial genomes. Based on an assessment of phylogenetic relationships, the pattern of estimated divergence dates, and the available fossil record, we suggest that the evolutionary history of M. fascicularis likely included multiple dispersal events. [ABSTRACT FROM AUTHOR]