Meeting Abstract

S11.4  Wednesday, Jan. 6  Axial Elongation in Fishes: Using Morphological Approaches to Elucidate Developmental Mechanisms in Studying Body Shape WARD, A. B.*; MEHTA, R. S.; Adelphi University; Univ. of California, Davis award@adelphi.edu

Fishes are highly variable in body shape: from nearly spheroidal in some Tetraodontiformes to extremely elongate in Anguilliformes. The elongate body shape has evolved at least twenty times independently within the ray-finned fishes, providing a unique situation for examining the underlying anatomical modifications associated with body elongation in a comparative context. Body elongation involves dramatic changes to the axial skeleton. Most elongate species have more vertebrae than closely related non-elongate relatives; those increases in vertebral number tend to be specific to one region of the vertebral column. Some lineages also show lengthening of the individual vertebral centra as the primary mechanism leading to body elongation. Additionally, highly elongated forms tend to have changes to other parts of the body including the fins and gastrointestinal tract. In previous studies, comparative analyses have provided hypotheses of developmental mechanisms that have led to morphological evolution. Many developmental studies are focused on mutations in model systems. Comparative morphological analyses can illuminate the findings of developmental studies by determining whether mutants in model systems correspond with morphological variability in a specific trait. In this study, we will review the evolution of body elongation across actinopterygian fishes and describe anatomical traits that are correlated with body elongation in these lineages. Finally, we will discuss hypotheses concerning the developmental control of body elongation in fishes.