Jeffrey Markert, Ph.D.
Evolutionary Genetics

Cichlid Population Biology and Speciation

Cichlid fishes are often viewed as an ideal model for illuminating the speciation process. The usual basis for this view is that cichlids are one of the most species-rich vertebrate families; lineages diverge frequently, providing opportunities to observe the lineage splitting in action.

Often overlooked is the fact that some cichlid subgroups are species-rich while others are species-poor. Interestingly, several behavioral, ecological and biogeographical variables span numerous species. Many of these transcend phylogenetic or biogeographical boundaries. Thus, the diversity of the East African cichlids provides an ideal and replicated comparative system in which to test the predictions of speciation models (Markert et al, 2001).

A key facet of my cichlid research program is the explicit quantification of basic population parameters in multiple taxa. Although cichlid researchers have made advances in understanding the mechanics of mate recognition, these observations are less informative than they might be since we lack detailed knowledge of fundamental population parameters such as the genetic effective population size and generation time. These population factors largely determine how long it would take for a new trait to become common in a population, the strength of selection needed to maintain traits in a taxon, and the evolutionary impact of gene flow between groups. By measuring these variables in multiple cichlid lineages and integrating them with ecological, behavioral and genomic data sets, we will be able to determine which sets of conditions drive lineage divergence within this highly diverse lineage.

Photos courtesy of The Cichlid Press
Cichlid Speciation Mysid Evolution Lake Malawi Congo Jeff Population Genetics Conservation Evolution Cichlidae Melanochromis Americamysis bahia mysidae AFLP American Museum of Natural History University of Rhode Island Environmental Protection Agency EPA

Original material (c) Jeffrey Markert - All rights reserved