Chromosomal evolution, speciation and morphological change in vertebrates: the role of social behaviour

Abstract

Rates of chromosomal evolution, morphological evolution and speciation are highly correlated among major vertebrate groups; however, there is not a direct relationship between evolutionary change at these different levels. To explain the correlation of evolutionary rates, we suggest that the evolution of social behaviour by certain mammals and birds facilitates evolutionary change at all three levels. Social behaviour may facilitate the successful founding of new populations by a small number of related individuals, a condition favouring fixation of chromosomal rearrangements that are selectively disadvantageous in the heterozygous state. We discuss two mechanisms, “behavioural drive” and “social selection”, whereby morphological change may beaccelerated by the evolution of social behaviour. Social behaviour may facilitate speciation both indirectly through its effects on population structure, and directly, by accelerating the evolution of mate recognition signals.