Meeting Abstract

7.1  Saturday, Jan. 4 08:00  Mechanical Transgressive Segregation and the Rapid Origin of Trophic Novelty HULSEY, CD*; HOLZMAN, R; Univ. of Tennessee, Knoxville; Tel Aviv University, Israel chulsey@utk.edu

Hybrid phenotypes often fall within the parental range. However, when morphological traits are complex,hybridization can generate mechanical phenotypes that segregate transgressively. For instance, even when the morphologies of individual musculo-skeletal components forming a complex functional system do not segregate outside the parental range in hybrid offspring, these systems can exhibit emergent phenotypes whose mechanics do transgress parental values. We examined three functional systems in the trophic apparatus of Lake Malawi cichlids to determine both the frequency of mechanical transgression segregation during hybridization and how the evolutionary divergence of parental species influences mechanical transgression. Generally, when genetic mechanisms underlie transgressive segregation, hybrids between more evolutionarily divergent species show greater transgression. However, two of the mechanical systems in the trophic apparatus exhibited a greater proportion of transgressive phenotypes in crosses between more recently diverged cichlid species. Hybridization does occur in the hundreds of co-occurring species and virtually every lineage we used in the simulations produced hybrids with transgressive mechanics. Therefore, mechanical transgressive segregation has likely helped shape the exceptional trophic diversity of the Lake Malawi cichlid radiation.