Large sequence divergence among mitochondrial DNA genotypes within populations of eastern African black-backed jackals.
AUTOR(ES)
Wayne, R K
RESUMO
In discussions about the relative rate of molecular evolution, intraspecific variability in rate is rarely considered. An underlying assumption is that intraspecific sequence differences are small, and thus variations in rate would be difficult to detect or would not affect comparisons among distantly related taxa. However, several studies on mammalian mitochondrial DNA (mtDNA) have revealed considerable intraspecific sequence divergence. In this report, we test for differences in the rate of intraspecific evolution by comparing mtDNA sequences, as inferred from restriction site polymorphisms and direct sequencing, between mtDNA genotypes of the eastern African black-backed jackal, Canis mesomelas elongae, and those of two other sympatric jackal species. Our results are unusual for several reasons. First, mtDNA sequence divergence within several contiguous black-backed jackal populations is large (8.0%). Previous intraspecific studies of terrestrial mammals have generally found values of less than 5% within a single population, with larger divergence values most often occurring among mtDNA genotypes from geographically distant or isolated localities. Second, only 4 mtDNA genotypes were present in our sample of 64 jackals. The large sequence divergence observed among these mtDNA genotypes suggests there should be many more genotypes of intermediate sequence divergence if they had evolved in sympatry. Finally, estimates of the rate of mtDNA sequence evolution differ by approximately 2- to 4-fold among black-backed jackal mtDNA genotypes, thus indicating a substantial heterogeneity in the rate of sequence evolution. The results are difficult to reconcile with ideas of a constant molecular clock based on random fixation of selectively neutral or nearly neutral mtDNA sequence mutations.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=53565Documentos Relacionados
- Mitochondrial DNA Sequence Divergence among Lycopersicon and Related Solanum Species
- Mitochondrial DNA clones and matriarchal phylogeny within and among geographic populations of the pocket gopher, Geomys pinetis.
- Mitochondrial DNA mapping of social-biological interactions in Brazilian Amazonian African-descendant populations
- Mitochondrial DNA mapping of social-biological interactions in Brazilian Amazonian African-descendant populations
- Genetic divergence among eggplant genotypes under high temperatures