Mitochondrial genes: signals and noise in the phylogenetic reconstruction of the annual killifish genus Cynolebias (Cyprinodontiformes, Rivulidae)

Abstract

The genus Cynolebias (Cyprinodontiformes: Rivulidae) is a locallyendemic and speciose group of Neotropical fishes with an annual lifecycle. Members of the genus vary greatly in morphology and behaviour,and extensive interspecific karyotypic divergence has been documentedamong species from Uruguay, Argentina and Rio Grande do Sul, Brazil. Wepresent a molecular systematic hypothesis of the relationships betweenthese Cynolebias species based on phylogenetic analysis of a combineddataset containing 1825 base pairs of DNA sequence, representing threemitochondrial genes. The protein-coding cytochrome-b gene, the 12S and16S rRNA mitochondrial genes, alone and in combination, yield robustsupport for monophyly within Cynolebias. Furthermore, our analysesidentify two major Cynolebias clades, one of which contains at leastfour monophyletic groups. Corrected mtDNA genetic distances range from5.2 to 17.5% between Cynolebias species, and application of a molecularclock suggests the occurrence of two pulses of cladogenesis, one in thelate Miocene and another in the Pliocene-Pleistocene. (C) 2002 TheLinnean Society of London.