Phylogenetic relationships and historical biogeography of spined loaches (Cobitidae, Cobitis and Sabanejewia) as indicated by variability of mitochondrial DNA

Abstract

For sequence analysis of the 12S rRNA gene in spined loaches, specimens of the following taxa were used: Sabanejewia balcanica, Cobitis paludica, C. bilineata, C. fahireae, C. elazigensis, C. elongata, two different subpopulations of C. taenia and four different sub-populations of C. turcica. Phylogenetic relationships among taxa were estimated using parsimony, neighbor-joining, and maximum likelihood algorithms. The calculation of the transition-tranversion ratio indicated that the taxa analysed were rather distantly related. Our analyses using the genus Sabanejewia as an outgroup suggest that C. bilineata is separated from the subgenus Cobitis sensu stricto and placed together with C. elongata as basal to all other species of the genus Cobitis. Support for the placement of C. paludica as basal to both the subgenera Bicanestrinia and Cobitis s.s. (without C. bilineata) is given by outcomes from three independent methods of phylogenetic reconstruction. A sister-taxon relationship for the subgenera Bicanestrinia and Cobitis s.s. without C. bilineata was consistently found. C. elazigensis was closely related to the population of C. turcica from Lake Beysehir in Turkey. Both formed a sister-group to the remaining populations of C. turcica, while C. fahireae was basal to C. taenia. A molecular clock was calculated based on sequence divergence values and palaeogeographical data. This suggests that different historical colonization routes must have been used by different clades of spined loaches. © 2001 The Linnean Society of London.