Tempo and mode of sequence evolution in mitochondrial DNA of HawaiianDrosophila

Abstract

Sequence comparisons were made for up to 667 bp of DNA cloned from 14 kinds of Hawaiian Drosophila and five other dipteran species. These sequences include parts of the genes for NADH dehydrogenase (subunits 1, 2, and 5) and rRNA (from the large ribosomal subunit). Because the times of divergence among these species are known approximately, the sequence comparisons give insight into the evolutionary dynamics of this molecule. Transitions account for nearly all of the differences between sequences that have diverged by less than 2%: for these sequences the mean rate of divergence appears to be about 2%/Myr. In comparisons involving greater divergence times and greater sequence divergence, relatively more of the sequence differences are due to transversions. Specifically, the fraction of these differences that are counted as transversions rises from an initial value of less than 0.1 to a plateau value of nearly 0.6. The time required to reach half of the plateau value, about 10 Myr, is similar to that for mammalian mtDNA. The mtDNAs of flies and mammals are also alike in the shape of the curve relating the percentage of positions at which there are differences in protein-coding regions to the time of divergence. For both groups of animals, the curve has a steep initial slope ascribable to fast accumulation of synonymous substitutions and a shallow final slope resulting from the slow accumulation of substitutions causing amino acid replacements. However, the percentage of all sites that can experience a high rate of substitution appears to be only about 8% for fly mtDNA compared to about 20% for mammalian mtDNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial DNA sequence variation and phylogeography of Pimelia darkling beetles on the Island of Tenerife (Canary Islands)

“…Las Cafladas volcano was formed between 1.9 and 0.2 My ago with the north and south valleys produced about 0.8 and 0.6 My ago. The two major mitochondrial groups in Tenerifean Pimelia show an average nucleotide substitution of 11 per cent with an estimated divergence time of 5.5 My, if we assume a constant substitution rate of 2 per cent per My (DeSalle et al, 1987). The within-group nucleotide substitution rate is 4.1 per cent and 3.7 per cent in the A and B groups, respectively (roughly 1.5-2 My of mitochondrial sequence divergence).…”

Molecular phylogeny of the Notostraca

“…However, for our divergence date estimation, we modified their 'method 2' by replacing 'I ij ' (=fraction of shared nucleotides between two sequences i and j) by '1 À (mean p-distance between lineages i and j)' and accordingly, we used average nucleotide frequencies of lineage i, and j, respectively, to infer the asymptotic identity for each of the two lineages. For divergence dating in the 16S gene, we applied 'clock rates' of 0.53%/Ma (Stillman and Reeb, 2001; calibrated by the divergence of porcelain crabs, genus Petrolisthes, at 3 Ma BP), of 0.02-0.04%/Ma, 0.06-0.12%/Ma (inferred from coral genera and families, respectively, see Romano and Palumbi, 1997) and of 0.05-0.2 and 0.07%/Ma (clocks calibrated by the divergence between Drosophila species, and between Aedes and Drosophila, respectively, as presented in Romano and Palumbi, 1997, referring to data from DeSalle et al, 1987).…”

Speciation and phylogeography of the Southeast Asian Anopheles sundaicus complex

“…Evolution rate estimations currently applied for Anopheles mtDNA are either 2% per million years calculated for the genus Drosophila (De Salle et al, 1987) or 2.3% for mtDNA of arthropods (Brower, 1994). However, differences between rates have been observed among mitochondrial markers (Fleischer et al, 1998;Simmons and Weller, 2001).…”