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Electric Fish Lab Uses Big Data to Study Evolution

Jason Gallant, assistant professor, Department of Zoology at Michigan State University, studies the genomic basis of phenotypic evolution and diversification, particularly in animal phenotypes that are related to communication behavior.

In January 2015, he received a $699,000 grant from the National Science Foundation to investigate the genomic basis of electric signal diversity in mormyrids, that is, fish that produce weak electric fields for the purposes of communication and navigation through their environments. As part of this three-year research project starting in May 2015, Gallant will leverage his recent discovery of a ‘hybrid zone’ between populations of electric fish with distinct electric signals to identify genes responsible for differences in electric signals.

According to Gallant, “Identifying genes responsible for behavioral differences within species will ultimately help biologists understand how changes in behavior can facilitate, or perhaps cause, one species to become multiple species.”

Here are two related research projects being conducted in Gallant’s “Electric Fish Laboratory” with the help of MSU’s Institute for Cyber-Enabled Research:

1. The Origin of Electric Organs in Fish
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Jason Gallant

Many studies have elucidated the genetic and developmental processes underlying major vertebrate traits (fins, limbs, etc.) in extant lineages. Most of these traits have evolved only once, limiting insights into the degree of constraint and repeatability of the evolutionary processes. In contrast with most other vertebrate traits, there have been six independent origins of electrogenesis in fishes – the ability to generate electric discharges from an electric organ. Despite their clear benefit as a model for understanding general principles of parallel evolution of complex vertebrate tissues, little is known about the molecular and developmental processes underlying this tissue. The long-term goal of the Electric Fish Laboratory at Michigan State University is to characterize the evolutionary steps that have occurred to modify the developmental program in skeletal muscle to give rise to the electric organ. Using cutting edge techniques in evolution and development (including transgenics, genomics and molecular biology), they plan to test the hypotheses concerning the roles of these genes in the evolution of electric organs.

2. The Evolution of Communication Diversity in Fish with Electric Discharge Signals (EODs)

Photo: Sullivan, John P. Paramormyrops kingselyae

The relative contribution of divergent natural selection and sexual selection on communication signals in the evolution of reproductive isolation is a central question in biology. Progress is limited by poor knowledge of how divergent communication signals originate at the genetic, cellular, and morphological levels, as well as difficulty connecting population-level processes prior to speciation with the macroevolutionary patterns of diversity observed after speciation is completed. The more than 200 nominal species of mormyrids (fish with the ability to generate weak electric fields that allow the fishes to sense their environment) are ideally suited for circumventing such problems, producing easily measured and quantified electric discharge signals (EODs), which have a discrete anatomical and physiological basis. EOD signals are typically species-specific and have been demonstrated to be a necessary component of courtship behavior, particularly for a rapidly evolved “species flock” of mormyrids in the genus Paramormyrops. Recently they have focused on linking these macroevolutionary patterns of electric signal diversity to population-level processes. They have identified a key species to use newly developed techniques in evolutionary genomics to identify genes responsible for macroevolutionary patterns of electric signal diversity, critical in the speciation process.

Institute for Cyber-Enabled Research (iCER)

Jason Gallant

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