69 - Modularity of the Cichlid Pharyngeal Skeleton: Developmental/genetic Origins and Evolutionary Consequences

Poster Board Number: 69
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Odd poster #s – first hour
Even poster #s – second hour

Co-authors:

Andrew Conith - DePaul University; Hewan Weldai - University of Massachusetts Amherst; Riley Kussmaul - University of Massachusetts Amherst; R Craig Albertson, PhD - PI, University of Massachusetts Amherst

Abstract Body : The evolutionary success of vertebrates has been credited to diversifying serially homologous elements of the pharyngeal skeleton. Stem vertebrates were thought to have possessed a series of uniform gill arches, which became individualized over evolutionary time, allowing different gill arch derivatives to take on diverse functions, including prey capture, processing, and filtering. Teleosts exemplify this trend with the evolution of a second set of pharyngeal jaws from the last gill arch. Overall, it appears that the pharyngeal skeleton has become more modular over evolutionary time; however, despite the significance of these events, neither the mechanisms through which the pharyngeal skeleton has become individualized, nor the developmental constraints operating on the system are known. Here, we use cichlid fishes to fill this knowledge gap. Notably, we document significant levels of shape correlation across the pharyngeal skeletal, suggesting that this trait complex may not be as modular as previously thought and that individualization may be constrained due to factors such as common developmental origins (e.g., neural crest cell). This being said, we did note differences in the explanatory power of correlations between elements, with the strongest correlation occurring between the oral and pharyngeal jaws. This trend suggests that the selection of common vs. diverse functions may influence the evolution of modularity in this system. A similar pattern was observed in a hybrid mapping population, which will allow us to determine the extent to which individualization (or lack thereof) is reflected in the genotype-phenotype map. This study will facilitate a better understanding of the causes and consequences of individualization of serially homologous parts. We want to acknowledge our grant funders, the NIH/NIDCR, for supporting this research.