Open AccessThe evolution of brain size among the Homininae and selection at ASPM and MCPH1 genes
Author(s) -
Sandra Leyva-Hernández,
Ricardo Fong-Zazueta,
Luis Medrano-González,
Ana Julia Aguirre-Samudio
Publication year - 2021
Publication title -
biosis
Language(s) - English
Resource type - Journals
eISSN - 2708-0072
pISSN - 2707-9783
DOI - 10.37819/biosis.002.02.0104
Subject(s) - biology , phylogenetic tree , genetics , evolutionary biology , gene , selection (genetic algorithm) , synonymous substitution , directional selection , nonsynonymous substitution , genetic variation , genome , codon usage bias , artificial intelligence , computer science
We examined the evolutionary relationship of the ASPM (abnormal spindle-like microcephaly associated) and MCPH1 (microcephalin-1) genes with brain volume among humans and other primates. We obtained sequences of these genes from 14 simiiform species including hominins. Two phylogenetic analyses of ASPM exon 3 and MCPH1 exons 8 and 11 were performed to maximize taxon sampling or sequence extension to compare the nucleotide substitution and encephalization rates, and examine signals of selection. Further assessment of selection among humans was done through the analysis of non-synonymous and synonymous substitutions (dN/dS), and linkage disequilibrium (LD) patterns. We found that the accelerated evolution of brain size in hominids, is related to synchronic acceleration in the substitution rates of ASPM and MCPH1, and to signals of positive selection, especially in hominins. The dN/dS and LD analyses in Homo detected sites under positive selection and some regions with haplotype blocks at several candidate sites surrounded by blocks in LD-equilibrium. Accelerations and signals of positive selection in ASPM and MCPH1 occurred in different lineages and periods being ASPM more closely related with the brain evolution of hominins. MCPH1 evolved under positive selection in different lineages of the Catarrhini, suggesting independent evolutionary roles of this gene among primates.