Convergent gene losses illuminate metabolic and physiological changes in herbivores and carnivores.

Abstract

The repeated evolution of dietary specialization represents a hallmark of mammalian ecology. To detect genomic changes that are associated with dietary adaptations, we performed a systematic screen for convergent gene losses associated with an obligate herbivorous or carnivorous diet in 31 placental mammals. For herbivores, our screen discovered the repeated loss of the triglyceride lipase inhibitor <i>PNLIPRP1</i>, suggesting enhanced triglyceride digestion efficiency. Furthermore, several herbivores lost the pancreatic exocytosis factor <i>SYCN</i>, providing an explanation for continuous pancreatic zymogen secretion in these species. For carnivores, we discovered the repeated loss of the hormone-receptor pair <i>INSL5</i>-<i>RXFP4</i> that regulates appetite and glucose homeostasis, which likely relates to irregular feeding patterns and constant gluconeogenesis. Furthermore, reflecting the reduced need to metabolize plant-derived xenobiotics, several carnivores lost the xenobiotic receptors <i>NR1I3</i> and <i>NR1I2</i> Finally, the carnivore-associated loss of the gastrointestinal host defense gene <i>NOX1</i> could be related to a reduced gut microbiome diversity. By revealing convergent gene losses associated with differences in dietary composition, feeding patterns, and gut microbiomes, our study contributes to understanding how similar dietary specializations evolved repeatedly in mammals.