Meeting Abstract

110.3  Sunday, Jan. 6  Wnt-signaling and the evolvability of cichlid craniofacial diversity PARSONS, KJ; POWDER, KE; ALBERSTON, RC*; Univ. of Glasgow; Univ. of Massachusetts, Amherst; Univ. of Massachusetts, Amherst rcraigalbertson@gmail.com

Evolvability refers to a population or clade’s ability to evolve in space or time. It deals with both constraint and opportunity, and has profound implications for how biodiversity arises and is maintained over time. East-African rift-lake (EA) cichlids are unquestionably one of the most successful adaptive radiations of any living organism, making them an ideal system in which to examine evolvability in the context of rapid diversification. Here we show that expanded Wnt-signaling has facilitated the evolution of phenotypic novelty and ecological opportunity in this group, but has done so at the expense of evolvability. Specifically, we show that increased Wnt-signaling is associated with the development of lineage specific craniofacial morphology, and that experimental modulation of Wnt-signaling recapitulates natural variation in craniofacial form. We demonstrate further that relative to other closely related and phenotypically similar species the lineage at the extreme end of EA cichlid craniofacial diversity expresses an adult phenotype much earlier in development, suggesting that the source of novel craniofacial variation may involve shifts in developmental timing. Moreover, this species expresses a phenotype that is both more robust to environmental change and more sensitive to molecular perturbation, which should act to limit adaptive responses. In short, the evolution of phenotypic novelty has increased ecological opportunity, but potentially at the expense of future evolution. These data offer some of the first empirical support for long-standing theories in evolutionary biology, and have important implications for the evolution and maintenance of biodiversity.