Habitat patchiness drives spatial structure in morphological trait variation and co-variation in spotted salamanders (Ambystoma maculatum)

Abstract

The influence of intraspecific trait variation on species interactions makes trait-based approaches critical to understanding eco-evolutionary processes. Because species occupy habitats that are patchily distributed in space, advancement in trait-based ecology hinges on understanding how trait variation is distributed within and between habitat patches. We sampled larval spotted salamanders (Ambystoma maculatum) across spatially discrete ponds to quantify within- and between-pond variation in mass, length, and their allometric relationship. Between-pond variation explained 7-35% of total observed variation in the length and shape of salamander larvae, depending on the body segment measured (i.e., head, body, or tail). Salamander tail morphology was more variable and exhibited more between-pond variation than head or body morphology. Salamander mass was highly variable and strongly correlated with total length. Allometric analysis revealed that the slopes of mass-length relationships were similar across ponds, but that intercepts differed across ponds. Preliminary evidence hinted that newly constructed ponds were a driver of the observed differences in mass-length relationships. Pond construction may therefore bolster trait diversity across the broader landscape, and in so doing instil more adaptive potential of salamander populations under current and future environmental change.