The Evolution of Jumping Performance and Associated Morphology in an Amphibious Fish: An Ontogenetic Perspectiv

Animals depend on numerous fitness-related performance characteristics for survival, and reproduction. Variation in these performance characteristics is often a consequence of selection on morphological variation. However, the link between morphology and performance is not always straightforward. Many anatomical arrangements may provide similar levels of performance. Thus, the evolution of performance characteristics may depend on the extent to which groups of morphological traits are correlated with one another and with performance, and the extent which this variation and covariation is due to genetic factors. However, the link between form and function as well as the genetic structure among morphological traits may vary across ontogeny. Despite this, few studies have taken an ontogenetic perspective when studying the evolution of performance and associated morphology. Here, I assess variation within and covariation among morphological (i.e. bones associated with the caudal peduncle) and performance (i.e. terrestrial jumping) traits to determine how the relationship between form and function, and heritable variation in and among functionally important morphological traits, change across ontogeny in the mangrove rivulus fish. I later determine how genetic variance/covariance among performance related traits have influenced divergence among populations, and if this relationship is age-dependent. Finally, using the genus Fundulus, I determine how natural selection posed by one selective force (i.e. salinity) may have influenced ontogenetic variation in morphology. Throughout I demonstrate that our understanding of morphological and performance evolution may by greatly enhanced by taking an ontogenetic perspective.