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Animals with biphasic lifecycles often inhabit different visual environments across ontogeny. Many frogs and toads (Amphibia: Anura) have free-living aquatic larvae (tadpoles) that metamorphose into adults that inhabit a range of aquatic and terrestrial environments. Ecological differences influence eye size across species, but these relationships have not yet been explored across life stages in an ontogenetic allometric context. We examined eye-body size scaling in a species with aquatic larvae and terrestrial adults, the common frog Rana temporaria, using a well-sampled developmental series. We found a shift in ontogenetic allometric trajectory near metamorphosis indicating prioritized growth in tadpole eyes. To explore the effects of different tadpole and adult ecologies on eye-body scaling, we expanded our taxonomic sampling to include developmental series of eleven additional anuran species. Intraspecific eye-body scaling was variable among species, with 8/12 species exhibiting a significant change in allometric slope between tadpoles and adults. Traits categorizing both tadpole ecology (microhabitat, eye position, mouth position) and adult ecology (habitat, activity pattern) across species had significant effects on allometric slopes among tadpoles, but only tadpole eye position had a significant effect among adults. Our study suggests that relative eye growth in the preliminary stages of biphasic anuran ontogenies is somewhat decoupled and may be shaped by both immediate ecological need (i.e. tadpole visual requirements) and what will be advantageous during later adult stages.
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Darter fishes exhibit variable intraspecific head shape allometry and modularity
Abstract Allometry, the relationship between anatomical proportions and body size, may either limit or facilitate the diversification of morphology. We examined the impact of allometry in darter fish morphology, which displays a variety of trophic morphologies. This study aimed to address (a) whether there was significant variation in darter head allometry, (b) if allometry contributed to head shape diversity in adults, and (c) if darters show head shape modularity associated with allometry. We used geometric morphometrics to quantify head shape across 10 different species and test for heterogeneity in allometric slopes. In addition, we quantified the degree of modularity between the preorbital and postorbital regions of the darter head, both before and after correction for body size. We found that different species have unique allometric slopes, particularly among theSimopercasubgenus, and that closely related darter species tend to show ontogenetic divergence, contributing to the diversity of head shapes observed in adults. We suggest that such a pattern may result from the similarity of juvenile diets due to gape limitation. We also found that several species show significant modularity in head shape but that modularity was evolutionarily labile and only sometimes impacted by head shape allometry. Overall, our work suggests that ontogenetic shape development may have been important to the evolution of head shape in darters, particularly in the evolution of foraging traits and microhabitat.
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- Award ID(s):
- 2135927
- PAR ID:
- 10486256
- Publisher / Repository:
- The American Association for Anatomy
- Date Published:
- Journal Name:
- The Anatomical Record
- Volume:
- 306
- Issue:
- 2
- ISSN:
- 1932-8486
- Page Range / eLocation ID:
- 446 to 456
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/ar.25088
