Meeting Abstract

45-3   14:00 - 14:15  Diadromy Drives Elevated Rates of Trait Evolution and Ecomorphological Convergence in Clupeiformes (Herring, Shad, and Anchovies) DeHaan, LM*; Burns, MD; Egan, JP; Bloom, DD; Western Michigan University, Department of Biological Sciences, Kalamazoo, MI.; Cornell University Museum of Vertebrates, Cornell Lab of Ornithology, Ithaca, NY ; Western Michigan University, Department of Biological Sciences, Kalamazoo, MI.; Western Michigan University, Department of Biological Sciences, Kalamazoo, MI. lmdehaan@umich.edu

Convergent evolution is a pervasive phenomenon across the tree of life. Many classic instances of morphological convergence focus on repeated transitions to similar habitat or trophic guilds however, the repeated evolution of a life history strategy may also alter the phenotypic adaptive landscape and drive morphological convergence. Diadromy is an extreme type of migration that requires individuals to move tens to thousands of kilometers between marine and freshwater habitats for feeding and reproduction. The high energetic demands of diadromy is predicted to select for ecomorphological traits that maximize swimming and locomotor efficiency. In fishes, numerous intraspecific studies have shown repeated instances of divergence among diadromous and non-diadromous populations in locomotor and foraging traits, which suggest that these repeated phenotypic patterns may persist among diadromous lineages at macroevolutionary scales and result in widespread convergent evolution. We tested for differences in rates and patterns of phenotypic evolution among diadromous and non-diadromous lineages in Clupeiformes, a clade that has evolved diadromy more than 10 times. Our results show that diadromous lineages have significantly faster rates of trait evolution than non-diadromous lineages. We found that traits associated with locomotion exhibit signatures of strong selection and diadromous lineages converged on three adaptive peaks in multivariate space. We propose that individual adaptive peaks are tied to specific parameters such as migration distance, swimming performance, and microhabitat. Our study demonstrates that long distance migration has a profound influence on the tempo and patterns of phenotypic evolution at macroevolutionary scales.