Genetic Basis of Parental Care in Cichlid Fish

Genetic Basis of Parental Care in Cichlid Fish

In recent years, cichlid fish have been of particular interest to geneticists studying vertebrate speciation and behavioral patterns in new animal models. Cichlid fish are any of the more than three thousand species belonging to the family Cichlidae in the order Perciformes. As they are typically freshwater fish, cichlids are most commonly found within lakes in tropical America, southern Asia, and Africa. The species in the lakes of Africa, including Lake Victoria and Lake Malawai, are of particular interest to researchers due to their recent diversification and speciation over the past million years (Kocher 2). The nearly 2,000 species of cichlid fish in East African lakes are closely related, making it easy to use genetic analysis to look for novel and recent evolutionary change. Specifically, the radiation of approximately 500 species in Lake Victoria and 700 species in Lake Malawi have occurred within the past one million years, and the radiation of approximately 250 species in Lake Tanganyika has occurred within the past six to eight million years (Kocher 4). All of these cichlids are thought to share a common ancestor with one of the most commonly cultured cichlids, the Nile tilapia or Oreochromis niloticus, from in the range of ten to fifteen million years ago (Kocher 5).

In the East African cichlid fish, there are two distinct forms of parental care that are common amongst the various lake species: substrate-guarding and mouth brooding. In substrate-guarding cichlids, both the male and female parents (although occasionally only female parents) typically will guard their eggs during all stages of development. Classic substrate brooding occurs when eggs are layed and fertilized on some sort of flat surface, area of sediment, inside shells on the sandy bottom of the lake, or in a small alcove or cave. The eggs then remain in this location, where they are protected by the parents (Sefc 2). In mouth-brooding, the...