Phylogenetic patterns in populations of Chilean species of the genus Orestias (Teleostei: Cyprinodontidae): results of mitochondrial DNA analysis.

Patterns of molecular genetic differentiation among taxa of the "agassii species complex" (Parenti, 1984) were analysed based on partial mtDNA control region sequences. Special attention has been paid to Chilean populations of Orestias agassii and species from isolated lakes of northern Chile, e.g., O. agassii, Orestias chungarensis, Orestias parinacotensis, Orestias laucaensis, and Orestias ascotanensis. Orestias tschudii, Orestias luteus, and Orestias ispi were analysed comparatively. Our findings support the utility of mtDNA control region sequences for phylogenetic studies within the "agassii species complex" and confirmed the monophyly of this particular lineage, excluding O. luteus. However, the monophyly of further morphologically defined lineages within the "agassii complex" appears doubtful. No support was found for the utility of these data sets for inferring phylogenetic relationships between more distantly related taxa originating from Lake Titicaca.

Phylogeographic patterns in populations of the black-chinned tilapia complex (Teleostei, Cichlidae) from coastal areas in West Africa: support for the refuge zone theory.

Within the tilapiines, a major African cichlid lineage, quite limited genetic informations are available on phylogenetic interrelationships and phylogeographical patterns at both macro- and micro-evolutionary scales. The present study examines the genetic diversity of the black-chinned tilapia complex from coastal areas in West Africa (Senegal to Congo-Brazzaville) based on mtDNA control region sequences. Phylogenetic inferences provide support for the monophyly of both taxa involved. It is suggested that Sarotherodon melanotheron and Sarotherodon nigripinnis have diverged probably since the early Pleistocene. The occurrence of the main intraspecific lineages could be dated back to about 500,000-900,000 years. Our data suggest that West African Pleistocene refuge zones may have strongly influenced the degree and level of genetic differentiation among populations and thus the observed phylogeographic patterns. The spatial distribution of mtDNA lineages and the centres of intrapopulational genetic diversity clearly correspond to proposed lowland refuge zones and core areas of Central Africa. Moreover, this study genetically supports the existence of Sarotherodon melanotheron leonensis for the first time and further confirms the validity of the most recently introduced subspecies, e.g., Sarotherodon nigripinnis dolloi.