genetic structure of pelagic and littoral fishes

[de Medeiros]

Genetic Structure of Pelagic and Littoral Cichlid Fishes
from Lake Victoria
Miyuki Takeda1, Junko Kusumi1, Shinji Mizoiri2, Mitsuto Aibara2, Semvua Isa Mzighani2,3, Tetsu Sato2,
Yohey Terai2, Norihiro Okada2,4*, Hidenori Tachida1*
1 Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan, 2 Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology,
Yokohama, Japan, 3 Tanzania Fisheries Research Institute (TAFIRI), Mwanza, Tanzania, 4 Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
Abstract
The approximately 700 species of cichlids found in Lake Victoria in East Africa are thought to have evolved over a short
period of time, and they represent one of the largest known examples of adaptive radiation. To understand the processes
that are driving this spectacular radiation, we must determine the present genetic structure of these species and elucidate
how this structure relates to the ecological conditions that caused their adaptation. We analyzed the genetic structure of
two pelagic and seven littoral species sampled from the southeast area of Lake Victoria using sequences from the mtDNA
control region and 12 microsatellite loci as markers. Using a Bayesian model-based clustering method to analyze the
microsatellite data, we separated these nine species into four groups: one group composed of pelagic species and another
three groups composed mainly of rocky-shore species. Furthermore, we found significant levels of genetic variation
between species within each group at both marker loci using analysis of molecular variance (AMOVA), although the nine
species often shared mtDNA haplotypes. We also found significant levels of genetic variation between populations within
species. These results suggest that initial groupings, some of which appear to have been related to habitat differences, as
well as divergence between species within groups took place among the cichlid species of Lake Victoria.