Evolutionary and plastic variation in larval growth and digestion reveal the complex underpinnings of size and age at maturation in dung beetles
Rohner, Patrick T.; Moczek, Armin (2023), Evolutionary and plastic variation in larval growth and digestion reveal the complex underpinnings of size and age at maturation in dung beetles, Dryad, Dataset, https://doi.org/10.5061/dryad.j9kd51cdc
Age and size at maturity are key life history components, yet the proximate underpinnings that mediate intra- and interspecific variation in life history remain poorly understood. We studied the proximate underpinnings of species differences and nutritionally plastic variation in adult size and development time in four species of dung beetles. Specifically, we investigated how variation in insect growth mediates adult size variation, tested whether fast juvenile growth trades-off with developmental stability in adult morphology, and quantified plastic responses of digestive systems to variation in food quality. Contrary to the common size-development time trade-off, the largest species exhibited by far the shortest development time. Correspondingly, species diverged strongly in the shape of growth trajectories. Nutritionally plastic adjustments to growth were qualitatively similar between species but differed in magnitude. Although we expected rapid growth to induce developmental costs, neither instantaneous growth rates nor the duration of larval growth were related to developmental stability in the adult. This renders the putative costs of rapid growth enigmatic. We further found that larvae that encounter a challenging diet develop a larger midgut and digest more slowly than animals reared on a more nutritious diet. These data are consistent with the hypothesis that larvae invest into a more effective digestive system when exposed to low-quality nutrition, but suggest that species may diverge readily in their reliance on these mechanisms. More generally, our data highlight the complex, and often hidden, relationships between immature growth and age and size at maturation even in ecologically similar species.
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Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Award: P2ZHP3_184003
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Award: P400PB_199257
National Science Foundation, Award: 1256689
National Science Foundation, Award: 1901680
John Templeton Foundation, Award: 61369