Meeting Abstract

10.1  Friday, Jan. 4  Parallel molecular signatures underlie convergent evolution in two bioluminescent squid PANKEY, MS*; OAKLEY, TH; Univ of California, Santa Barbara; Univ of California, Santa Barbara sabrina.pankey@lifesci.ucsb.edu

The phenomenon of convergent phenotypic evolution fascinates biologists, largely because the extent to which convergent molecular processes drive convergence at the phenotypic level remains unclear. Natural selection is frequently invoked to explain how taxa facing similar biotic or abiotic pressures may arrive at similar phenotypic solutions. This study seeks to understand if the range of possible ‘molecular solutions’ for a complex trait is similarly limited. Cephalopod molluscs include two distinct clades of squid that harbor closely related strains of luminous bacterial symbionts within elaborate, optically enhanced organs called “photophores”. Using next-generation sequencing, we have generated transcriptomes from two divergent squid to characterize the gene expression patterns of bacterial photophores that have originated independently. Comparisons between these transcriptomes have uncovered striking similarities in the molecular profiles underlying these distinct traits. Notably, homologous genes known to be involved in mediating pathogenicity, bacterial recognition, and light perception are highly expressed in both organs. Within each species, additional transcriptional similarity between eyes and photophores suggests a molecular mechanism for the functional convergence observed in these traits. This study contributes not only to symbiosis biology, but also to our understanding of how similarity in molecular profiles relates to morphological and functional similarity.