COLLEGE PARK, Md. -- An international team of scientists has discovered how changes in both gene expression and gene sequence led to the diversity of visual systems in African cichlid fish.
In research published in the December 21, 2009 issue of the journal PLoS Biology, Assistant Professor Karen Carleton, together with post-doctoral associate Chris Hofmann and graduate student Kelly O'Quin, in the University of Maryland Department of Biology, and collaborators Justin Marshall, University of Queensland; Tom Cronin, University of Maryland, Baltimore County (UMBC); and Ole Seehausen, University of Bern; describe how over 60 species of cichlid fish from Lake Malawi and Lake Victoria have adapted their visual sensitivity in response to specific ecological factors, including what they eat and the clarity of the water in which they swim.
Evolutionary biologists seek to understand the mechanisms behind genetic changes that have led to the vast diversity of life on Earth. There are two important molecular mechanisms that contribute to organismal diversity - changes to the sequence of genes, and changes in the way genes are expressed, including when, where, and how much of a gene is made. This study was one of the first to look at how both gene sequence and gene expression can contribute to the same trait, and showed that they contribute in complementary ways.
"African cichlid fishes are some of the most diverse animals on the planet. Their visual systems differ dramatically in their sensitivity and represent some of the largest differences known in vertebrates," explains Hofmann. "Yet there has been little understanding as to why such diversity exists. Our findings have important implications for understanding both the factors and the mechanisms responsible for generating biodiversity."
Cichlids have several different cone opsin genes that enable them to detect light across the visible and ultraviolet regions of the spectru
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University of Maryland