Kevin J. Roe

Systematics, evolution, & conservation

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Central  American Mussels
 
KJR and Volcan Concepcion

Here I am on the shores of Lake Nicaragua with Volcan Concepcion in the background.


As part of my research program investigating the evolution and systematics of freshwater mussels, I have started exploring the understudied unionoid fauna in Central America.
The first stop, on what I intend to be a long-term collaborative investigation is
Lake Nicaragua, also known as Cocibolca, or "the sweet sea" by locals.  Lake Nicargua is one of the largest freshwater lakes in the Western Hemisphere.  The lake is approximately 3 million years old and was formed by volcanic and tectonic activity.  The lake is home to a relatively diverse fish community which includes members of several families including Cichlidae, Characidae, Megalopidae, Pimelodidae, Lepisosteidae, Poeciliidae, as well as Carcharhinidae, and Pristidae.  The freshwater bivalve fauna is also fairly diverse and inlcudes members of two families: Unionidae and Mycetopodidae.


The first of (hopefully) many trips to Nicaragua was recently successfully completed!
During the trip I accomplished several goals including collection live freshwater mussels representing the three families found in Nicaragua.  These specimens will be examined and represent an important part of a planned monograph of the freshwater mussels of Lake Nicaragua.  Tissue samples were also preserved for DNA extraction and sequencing.


Thanks to the assistance of Stephen Robinson (undergraduate, Iowa State University), the Nicaraguan project is moving forward. Stephen is making headway sequencing two mitochondrial genes for specimens collected in Nicaragua, and is using his artistic talents to prepare illustrations for the upcomming monograph on the unionids of Lake Nicaragua. A preliminary phylogeny of North American unionids inluding some of our Nicaraguan specimens was presented at the 2006 meeting of the American Malacological Society in Seattle, and can be seen below.  These results imply that Central American unionids are dispersed throughout the phylogeny of their northern cousins and has implications for the evolution of characters and life-history traits in the Unionidae.

Nica_tree

The phylogenetic hypothesis above traces the number of demibranchs (all 4, or outer or inner 2) that are used to brood larvae. Nicaraguan taxa are highlighted by the blue and red boxes.






 

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