Social structuring of mammalian populations and rate of chromosomal evolution.

Abstract

To test the hypothesis that the evolution of organisms is dependent to a large degree on gene rearrangement, we devised a way of estimating rates of evolutionary change in karyotype. This non-biochemical method is based on consideration of chromosomal variability within taxonomic groups having a fossil record. The results show that chromosomal evolution has been faster in placental mammals than in other vertebrates or molluscs. This finding is consistent with published evidence that placentals have also been evolving unusually fast in anatomy and way of life. However, the structural genes of placentals seem not to have experienced accelerated evolution. Possibly, therefore, anatomical evolution may be facilitated by gene rearrangement.To explain how placentals achieved this high rate of chromosomal evolution, we consider the process by which a new gene arrangement becomes fixed and spreads.

Chromosome Inversions, Local Adaptation and Speciation

“…The mechanism might also contribute to the correlation observed between rates of speciation and rates of karyotypic change (Wilson et al 1975;Bush et al 1977;Bengtsson 1980). Speciation can be driven by adaptation to novel habitats (Schluter 2000).…”

Effects of inbreeding on infant mortality in captive primates

“…He believes this preference is a common cause of emigration. Wilson et al (1975) believed that the apparently rapid rates of chromosomal evolution m primates and some other mammals indicate that these animals often inbreed in the wild. However, Schwartz and Armitage (1980) disagreed with this view on the basis of their data on yellow-bellied marmots, Marmotaßaviventris, which they beheve may be characteristic of many other mammalian species.…”

An examination of the role of chiasma frequency in the genetic system of marsupials

“…In contrast, the correlations between recombination level and the biological features considered in the 2n = 16 macropodids were not significant, even though the species have a two-fold range of chiasma frequency. However, the underlying trend in the macropodids and nonmacropodids may well be the same, since the signs of the calculated correlation coefficients are the same (compare tables 5 and 6, and the 2n = 14 and 2n = 16 groups in been suggested that chromosome number varies due to other pressures such as social organisation and drift (Wilson et al, 1975;Bengtsson, 1980), which would appear to operate irrespective of their subsequent effect on the level of recombination, so that only the EC might be easily open to evolutionary modification due to its effect on recombination level (Darlington, 1932;John and Lewis 1975). The other karyotypic feature considered, DNA content, was not correlated with either of the indices of recombination.…”