Meeting Abstract

32.1  Friday, Jan. 4  Multiple origins of the adipose fin and the morphological diversification of novel vertebrate appendages STEWART, TA; Univ. of Chicago tomstewart@uchicago.edu

Adipose fins are appendages found between the dorsal and caudal fins of some teleost fishes. Their evolutionary history is poorly understood, as is their function. These fins are often regarded as vestigial in the literature, and adipose fins are clipped off by the millions by fishery agencies as a means of tracking salmon. Using a recent phylogeny of actinopterygian fishes I demonstrate that adipose fins have evolved independently at least twice, once in the Otophysi clade excluding Cyprprinidae (i.e.: Characiformes, Siluriformes, and Gymnotidae), and again within the Euteleostei. Thus, as convergent novel appendages, I argue for their functionality and explore the diversity of adipose fin anatomies that have evolved within these two groups by comparing their variation in shape and composition. From these surveys I identify muscles that insert upon the adipose fins of several families of catfishes (Siluriformes). This implies the repeated innovation of musculoskeletal linkage systems among adipose fins. This study highlights these structures as an emerging model system by which to study the evolution of structural complexity and function in vertebrate appendages.