Abstract
Parallel evolution of the body shape and trophic-related traits has been detected between sympatric pairs of lake-dwelling characin fishes in Mesoamerica. Here, we evaluated the variation in and the ontogenetic allometric trajectories of trophic morphology between sympatric Astyanax morphs (elongate and deep-body) in two geographic systems, Lake Catemaco (Mexico) and San Juan River basin (Nicaragua and Costa Rica). Using geometric morphometrics, we determined the shape variation and disparity in the premaxillary bone, and the patterns of allometric trajectories between morphs in each system. We found a higher differentiation and disparity in the premaxilla shape between morphs from San Juan River basin than between the Lake Catemaco ones. We found shared (parallel evolution) patterns of divergence between systems, which included allometric trajectories showing a positive correlation between the premaxilla shape and log centroid size, as well as trajectories being extended in the elongated-body morph (truncated in the deep-body morph). Regarding the unique patterns of divergence, we recovered parallel allometric trajectories between morphs from Lake Catemaco, while the San Juan River basin morphs showed divergent trajectories. Our results are congruent with the hypothesis that divergence in trophic morphology can be considered a triggering factor in the divergence in the genus Astyanax from Mesoamerica.
Highlights
Published: 30 August 2021Body size influences many traits in animals [1,2,3,4,5]
Allometry is defined as the variation in morphometric variables or other features of organisms associated with size
We found a shared pattern of divergence in the premaxilla shape between morphs in the two systems analyzed (Figure 2)
Summary
Published: 30 August 2021Body size influences many traits in animals [1,2,3,4,5]. Allometry is defined as the variation in morphometric variables or other features of organisms associated with size. Ontogenetic allometry could contribute to evolutionary diversification, as has been described in studies of morphological diversification associated with ontogenetic allometric trajectories at intra- and interspecific levels (e.g., [7,8,9,10,11,12]). According to the latter idea, changes in ontogenetic trajectories could have an adaptive basis, being useful to the study of how different selective pressures imposed by ecological factors could affect development [10,12,13].
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