What regulates how plants and animals are distributed on Earth remains a long-standing question in the fields of ecology and biogeography. In light of the theory of natural selection, we can expect that geographically distinct populations of a species will differ at least slightly in their adaptations to their respective local conditions. One approach to elucidate how a species adapt to local conditions (a.k.a. local adaptation) is to assess whether some of its key functional traits vary predictably along broad-scale environmental gradients. This research aims to test whether intraspecific variations in morphology tract environmental gradients in North American ants. To achieve this, we use a unique dataset of georeferenced and highly precise morphometric measurements of thousands of individuals of 33 species of ants in the genus Formica.
Results/Conclusions
Thus far, our analyses have shown that body size in North American Formica does not increase with increasing latitude. Contrary to our expectations, body size in the queens and workers of some species decreased at higher latitudes. These results are contrary to the ones found in previous studies in ants. We propose that shorter growing seasons at northern latitudes explain the reduced size of ants in some species. Our results further our understanding of how and why functional traits, specifically body size, vary at the intraspecific level along gradients. Furthermore, our results also suggest that a reduction in size is a potential constraint limiting the distribution of ant species living in cold and highly seasonal environments.