Genetic relationships of cichlid fishes from Lake Malawi based on mitochondrial DNA sequences
2020
Hashem, Shaharior | Kawai, Koichiro | Fatsi, Patrick Senam Kofi | Kodama, Atsuya | Saitō, Hidetoshi
The purpose of this study was to estimate the genetic distance, diversity and relationship of two large groups of Malawian cichlid, ‘mbuna’ living in rocky area and feeding on algae, and ‘non-mbuna’ in sandy area feeding on various items. A total of 78 species from 42 genera was determined for the DNA sequence of the mitochondrial control region. In a genetic tree, constructed with Kimura-2 parameter as a distance by NJ method, mbuna created only one group whereas non-mbuna created four groups by a single or multiple genera. Some genera, such as Campsochromis and Labeotropheus with no genetic diversity within genus constructed a small congeneric clade, suggesting genetic homogeneity. In contrast, some genera, such as Otopharynx and Placidochromis with a high genetic diversity, participated in multiple groups including mbuna and non-mbuna, suggesting genetic heterogeneity. The largest Group A, exclusively composed by non-mbuna, showed an apparently high average genetic distance whereas Group D, in which all mbuna participated, showed an apparently low average genetic distance. It was suggested that non-mbuna have attained much higher diversification than mbuna. This different diversification may partly be attributable to sexual selection strongly exerted in rocky habitats in contrast to strong ecological selection in sandy area.
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