Meeting Abstract

50.3  Tuesday, Jan. 5  Comparative Evolutionary Dynamics in Cichlid Adaptive Radiations: Linking Lower Jaw Genetics, Morphology, and Mechanics HULSEY, CD*; STREELMAN, JT; Univ. of Tennessee; Georgia Institute of Technology chulsey@utk.edu

The lower jaw is a major determinant of feeding diversification in cichlid adaptive radiations. It also provides an ideal phenotype to compare rates and patterns of macroevolution among cichlid radiations. Using a novel phylogeny of four genes (ND2, Dlx2, Mitfb, and S7), we examine the phylogenetic relationships among two of the most evolutionarily disparate cichlid radiations: 1) the Heroines of Central America and 2) the Lake Malawi species flock. To quantify jaw morphology, we measured the in-levers and out-levers of the lower jaw in approximately 40 species in each flock respectively. Then we examined the modularity of the jaw across the phylogeny and compared how integrated the jaw was in the two radiations. Using several external calibration points, we also generated a time-calibrated chronogram for both groups and examined the evolutionary rates for morphology and mechanics. The rates differed in surprising ways between the two clades.