Changes in spatial behaviour patterns by mangrove tree crabs following climate-induced range shift into novel habitat

Abstract

Climate-mediated range shifts into eco-evolutionary novel habitats have the potential to alter the ecology and behaviour of range-expanding species. Of particular concern are behaviours that have a strong impact on the ecology and life history of expanding species. Behaviours that control the spatial patterns of habitat use may be particularly important. We examined site fidelity and foraging foray behaviour of the mangrove tree crab, Aratus pisonii, in its historic mangrove habitat and the recently colonized eco-evolutionary novel salt marsh. In the mangrove, A. pisonii showed both strong site fidelity to individual trees and a foraging pattern wherein they made foraging forays that decreased in frequency as their distance from the home tree increased; but they displayed neither behaviour in the salt marsh. Chemical cues from faeces appear to be the mechanism behind site fidelity in the mangrove and may suggest the mechanism for the loss of this behaviour in the salt marsh where substrate is regularly submerged, potentially preventing establishment of such cues. The loss of site fidelity may affect the foraging behaviour and predation risk of A. pisonii in the salt marsh, leading to a shift in its ecology and bioenergetics. As more species are forced to shift ranges into eco-evolutionary novel habitats, it is important to understand how this shift may affect their life history, behaviour and ecology in indirect ways.