Abstract:
Phenotypic plasticity can favor the emergence of different morphotypes specialized in
specific ranges of environmental conditions. The existence of intraspecific partitioning confers
resilience at the species scale and can ultimately determine species survival in a context of global
changes. Amblystogenium pacificum is a carabid beetle endemic to the sub-Antarctic Crozet Islands, and
it has two distinctive morphotypes based on body coloration. For this study, A. pacificum specimens
of functional niches were sampled along an altitudinal gradient (as a proxy for temperature), and
some morphological and biochemical traits were measured. We used an FAMD multivariate analysis
and linear mixed-effects models to test whether these traits were related to morphotype, altitude, and
sexual dimorphism. We then calculated and compared the functional niches at different altitudes
and tested for niche partitioning through a hypervolume approach. We found a positive humpshaped
correlation between altitude and body size as well as higher protein and sugar reserves in
females than in males. Our functional hypervolume results suggest that the main driver of niche
partitioning along the altitudinal gradient is body size rather than morphotype or sex, even though
darker morphotypes tended to be more functionally constrained at higher altitudes and females
showed limited trait variations at the highest altitude.
Description:
DATA AVAILABILITY STATEMENT : The data presented in this study are openly available on FigShare at
https://doi.org/10.6084/m9.figshare.21444753.v1 and on GitHub at https://github.com/CamilleCoux/
A_pacificum/tree/main/data. The R scripts from the analyses in this article are available on GitHub
at https://github.com/CamilleCoux/A_pacificum.