Exploring The Genetic Basis Of Primate Body Size

Primates has gradually evolved into different body size over a long evolutionary history and is an ideal model for studying the evolution of primate.The largest of these is the Gorilla(Gorilla gorilla),which weighs up to 105 kilograms,while the smallest one is the squirrel lemur(Microcebus murinus),which weighs only 56 grams.In addition,primate species experienced events that their brain size have increased during evolution.However,the molecular basis for primate body size and brain size is not yet clear.Therefore,in this study,we explored the molecular basis of primate body size and brain size.Through literature search,we collected data on the four morphological indicators of body length,body weight,brain weight and encephalization quotient(EQ)of 25 primate species,and downloaded published genomic data(25 primates and near-species mice)from the NCBI database.1:1 orthologous genes were identified from 26 species by the Ortho Finder software,and the molecular evolution rate for each of the 1:1orthologous gene in each species was calculated using PAML software.Then,through PGLS regression analysis,the four morphological index data were associated with the evolutionary rate of 1:1 orthologous gene.323 genes associated to body length and body weight(the sum of body length related genes and body weight related genes)were screened.Functional enrichment analysis shows that these genes are mainly enriched in pathways such as cell cycle,the oxidation and metabolism of fatty acid and regulation of thyroid hormone levels,which provide hormones and energy for body development,suggesting that these pathways may play a key role in primate body size evolution.In brain size regression analysis,we detected 150 and 169 genes associated with brain weight and EQ,respectively.Interestingly,genes associated with brain weight are mainly concentrated in the pathways associated with ubiquitin protease binding,neuronal receptor-ligand interactions,and cell cycle related pathways,which play an important role in regulating the release and precise transmission of neurotransmitters.Genes associated with EQ are mainly concentrated in pathways associated with external stimulation and visual perception,which may have something to do with visual memory based on visual observation and perceptual empirical memory of external stimuli.The above results suggest that synaptic transmission between neurons,the perception of external stimuli,and the genes involved in visual evolution may play a key role in the evolution of brain size.In this study,genes associated with body size and brain size were screened at the genome-wide level,and then,gene function enrichment analysis was performed.The molecular basis of primate body size and brain size evolution was preliminarily discussed.