The relationship between body shape and air-breathing organ morphology in Anabantarian fishes as revealed by morphometrics

Elizabeth Ajaero

Pronouns: she/her/hers

Research Mentor(s): Matthew Kolmann, Postdoctoral Researcher
Research Mentor School/College/Department: Museum of Paleontology, College of Literature, Science, and the Arts
Presentation Date: Thursday, April 22, 2021
Session: Session 1 (10am-10:50am)
Breakout Room: Room 13
Presenter: 7

Event Link

Abstract

The Anabantarians are a diverse group of tropical, freshwater fishes which use air-breathing organs (ABO) within their skulls to live in harsh environments (e.g., warm, hypoxic pools). Space is limited within the skull however, suggesting that evolutionary changes to ABO size and shape can influence neighboring skeletal structures, a concept called morphological integration. We conducted this study to determine if there is a correlation between the modularity of fishes and the presence of an Air-Breathing Organ (ABO). The discovery of how the introduction of a new structure within a limited space, such as the skull, affects the relationship between neighboring structures, can help the science community better understand what affects integration between structures. While conducting this study we examined all Anabantarian families (e.g., Anabantidae, Osphronemidae, Badidae). We hypothesized that the presence of an ABO would create a more integrated cranial skeleton, and as a result decrease the modularity of the fish overall. To test this, fish skeletons were visualized through x-ray imaging, and aspects of fish phenotype were measured using linear morphometrics. We compared body shape metrics that correspond to aspect ratio, cranial elongation, and post-cranial elongation among fishes with and without ABOs. Our findings demonstrated that air-breathing organs have evolved 2-3 times, independently across anabantarians, and although fishes with ABOs are more diverse than fishes without, these findings were not statistically significant. Relatedly, there were no significant differences in body shape metrics among air-breathing and non- air-breathing fishes; however, the body shapes of fishes with ABOs evolve as much as 3.5 times faster than those fishes without.

Authors: Elizabeth Ajaero, Matthew Kolmann, Matthew Friedman
Research Method: Computer Programming