Meeting Abstract

P2.99  Monday, Jan. 5  The evolution of fin reduction and loss in fishes RADE, C. M.*; CIUMMO, E. M.; WARD, A. B.; Adelphi University; Adelphi University; Adelphi University cristinarade@adelphi.edu

Body elongation has evolved a number of times independently in vertebrates. In highly elongate vertebrates, the limbs/fins are often reduced or lost. For example, a number of elongate tetrapods have been described as having reduced limbs; many times in association with a transition to a burrowing habit. Less is known about changes to the fins in elongate fish lineages. Previous study has shown that loss of the pelvic fins has occurred in a number of fish lineages regardless of body shape. The goal of this study was to determine whether there is fin reduction in fish lineages where there is body elongation and to determine the specific musculoskeletal changes associated with fin reduction in fishes. In this study, we collected fin and body measurements from a number of ostariophysan and gasterosteiform species. Additionally, we have described the musculoskeletal anatomy for at least two species that differ in degree of body elongation from both Ostariophysi and Gasterosteiformes. Highly elongate members of these lineages do not have pelvic fins. Our results indicate that the pectoral fins are smaller in more elongate fishes in these lineages. In examining the musculoskeletal system of elongate and non-elongate species from the same lineage, we have found that there is a difference in number and arrangement of the pectoral fin muscles between closely related elongate and non-elongate species. This work provides a critical basis in understanding anatomical changes to the paired fins that are associated with changes in body shape.