Disparate Rates of Molecular Evolution in Cospeciating Hosts and Parasites

Abstract

DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times.

Trees within trees: phylogeny and historical associations

“…Processes such as gene duplication, lineage sorting and horizontal transfer can produce complex gene trees that differ from organismal trees 3,7,8 . Associations between organisms, such as between hosts and their parasites 9 (including viruses 10 ), endosymbionts and their hosts 11 , and insects and plants 12,13 , can have a long evolutionary history, which is reflected in similarities between their evolutionary trees 14 . At a larger scale still, organisms can track geological history such that sequences of geological events (e.g.…”

A Different Tempo of Mitochondrial DNA Evolution in Birds and Their Parasitic Lice

“…the absolute age of those cospeciation events. Relative rates of molecular evolution have been measured in this way between chewing lice and mammals (Hafner et al, 1994) and endosymbiotic bacteria and aphids (Moran et al, 1995).…”

Exact Bipartite Crossing Minimization under Tree Constraints

“…A tangle edge then specifies which host is affected by which parasite. Whereas in the first application the number of tangle edges incident to a leaf is always one, in the latter their degree can be higher, as shown below in a tanglegram from Hafner et al [6] (here the hypothesis seems to be true). Tanglegrams also occur in hierarchical clusterings, which can be visualized by so-called dendrograms.…”