Meeting Abstract

5.3  Saturday, Jan. 4 08:30  Body and fin shape evolution in cichlid fishes FEILICH, K.L.; Harvard University, Cambridge, MA kfeilich@fas.harvard.edu

Cichlid fishes (Acanthomorpha: Cichlidae) are some of the most morphologically and behaviorally diverse fishes in the world. Their morphological disparity, especially of feeding structures, is well-documented. Despite this, comparatively little is known about how swimming morphology has evolved. I am using cichlid fishes as a model system, bringing together morphometrics, robotics, and biomechanics to determine the effects of post-cranial morphology on fish swimming performance. In this study, I examined body, caudal, pectoral and dorsal fin shape in cichlid fishes spanning the group’s phylogeny. Using a combination of traditional and geometric morphometrics, I analyzed 29 body landmarks from digital x-rays, and the lengths of fin bases, fin spines, and fin rays to examine patterns of variation and co-variation in cichlid body shape evolution. Principle components analysis separated cichlid body shapes by aspect ratio, with rounded fishes like Symphysodon and tapered fishes like Benthochromis appearing at opposite ends of PC1. More than 80% of variation in caudal fin shape was explained by a single principle component, reflecting a caudal fin’s degree of “forkiness”. By incorporating information from the cichlid evolutionary tree into morphometric comparisons, I revealed patterns in the evolution of body and fin shape, and how they may be constrained by phylogenetic history. For instance, African cichlids fail to invade parts of morphospace occupied by Neotropical cichlids. Patterns in the evolution of locomotor structures may be related to ecology and contribute to differences in swimming performance. Future studies linking morphology to swimming performance may reveal adaptive trends in patterns of morphological evolution.