It’s complicated Examining convergent evolution of craniofacial morphologies in apteronotid and mormyrid electric fishes


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


40-5  Sat Jan 2  It’s complicated: Examining convergent evolution of craniofacial morphologies in apteronotid and mormyrid electric fishes Ford, KL*; Bernt, MJ; Peterson, R; Albert, JS; University of Louisiana at Lafayette; American Museum of Natural History, University of Louisiana at Lafayette; George Washington University; University of Louisiana at Lafayette klf8880@louisiana.edu http://www.kassandraford.com

Weakly electric fishes provide an opportunity to examine multiple instances of morphological convergence across continents. Gymnotiformes and Mormyridae use weak electric signals for prey detection, predator avoidance, and social communication. Species within each lineage inhabit deep river channels, shallow streams, and flooded plains, but it is unclear how these habitat types influence morphology. Snout length and shape are affected by prey type and availability, both of which are strongly influenced by a habitat’s water velocity and habitat complexity. Two families of electric fishes, Apteronotidae (Gymnotiformes) and Mormyridae (Osteoglossiformes), exhibit a particularly high range of head shape disparity. A few studies have examined the similarities between the external morphologies of species in these two lineages, but we have yet to quantify the morphologies of internal head structures. Individuals from Apteronotidae (43 species, n=160 specimens) and Mormyridae (41 species, n=229 specimens) were analyzed using 3D geometric morphometrics with 22 homologous landmarks. Specimens were CT-scanned and analyzed using the programs 3D-Slicer and Geomorph. Procrustes ANOVA and multivariate regressions were used to analyze morphological similarities, which were then traced on phylogenetic trees. Ancestral trait reconstructions were performed using maximum likelihood. Results indicate multiple instances of significantly convergent morphologies, but only within families. Convergent morphologies were not found between families. These results invite further study into the roles of natural selection and developmental constraints in the production of convergent phenotypes.

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