Meeting Abstract

LBS3.6  Friday, Jan. 4  The results of replicate radiation: reconstructing parallel ecomorphological diversification in African and South American characiform fishes SIDLAUSKAS, B. L.; National Evolutionary Synthesis Center bls16@duke.edu

Though rare in nature, replicated runs through the same evolutionary scenario can test the generality of resulting macroevolutionary patterns. Since the separation of South America and Africa, a group of characiform fishes with high morphological and ecological diversity arose as sister to a group of morphologically depauperate detritivores on both continents independently. By mapping phylogeny and trophic ecology into a morphospace derived from skull anatomy, reconstructing ancestral morphologies for internal nodes and calculating the direction of evolution and morphometric distance covered by each branch of the phylogeny, similarities and differences in the pattern of ecomorphospace occupation on each continent are revealed. Preliminary results suggest that 1) some, but not all species with convergent ecologies evolved similar skull shapes; 2) detritivores and carnivores tended to evolve in opposite morphometric directions, as did invertivores and herbivores; 3) subclades with low overall morphological diversity were not always associated with small morphological changes on the branches of the phylogeny, but may have resulted instead from the dense packing of branches in particular regions of morphospace and 4) major alterations in the anatomy of the lower jaw joint in association with the evolution of a benthivorous ecology occurred before bursts of additional change in skull and jaw shape and trophic ecology on both continents. Overall these results suggest that specialization on detritus may dampen further trophic and morphological diversification, while specialization on benthos and/or alterations in lower jaw morphology may tend to spark additional trophic and morphological evolution, perhaps by opening up new regions of morphospace.