Meeting Abstract

7.2  Saturday, Jan. 4 08:15  An empirical approach to assess the relationship between evolvability and fitness in East African cichlids CONCANNON, MR*; HU, Y; POWDER, KE; ALBERTSON, RC; UMass Amherst; UMass Amherst; UMass Amherst; UMass Amherst mrconcan@cns.umass.edu

Organismal characters such as developmental plasticity, phenotypic integration, and relative morphology can influence evolvability, but how these factors interact with fitness during major evolutionary events is less clear. In the impressive adaptive radiation of East African cichlids, an initial divergence in benthic and limnetic foragers ultimately led to the incredible species diversity seen today. We designed an experiment to elucidate the interplay of fitness and organismal traits during niche partitioning along the benthic/limnetic axis. We utilized a lab-reared hybrid population that exhibits transgressive segregation in craniofacial morphology along this axis relative to the parental species. We induced competition in hybrids by offering a limited amount of two food choices with identical nutritional content: food dried on rocks to mimic a benthic/scraping diet, and finely ground food to mimic a limnetic/suction feeding diet. Changes in craniofacial shape and phenotypic integration were tracked over the course of the experiment. In addition, we also measured proxies of fitness including growth rate, reproductive investment, and survival. We investigated correlations among all these measures to identify traits associated with peaks on the fitness landscape, which may therefore be paramount in species divergence. Notably, since this experiment is performed in a mapping cross, we have the ability to identify the genetic bases of these traits, thereby lending important and novel insights into the relationships among traits traditionally associated with evolvability and those related to fitness.