How to behave when marooned: the behavioural component of the island syndrome remains underexplored

Abstract

Animals on islands typically depart from their mainland relatives in assorted aspects of their biology. Because they seem to occur in concert, and to some extent evolve convergently in disparate taxa, these changes are referred to as the “island syndrome”. While morphological, physiological, and life history components of the island syndrome have received considerable attention, much less is known about how insularity affects behaviour. In this paper, we argue why changes in personality traits and cognitive abilities can be expected to form part of the island syndrome. We consider the ecological drivers that may induce such changes, and the mechanisms through which they might occur. Finally, we provide an overview of studies that have compared personality traits and cognitive abilities between island and mainland populations, or among islands. Overall, the pickings are remarkably slim. There is evidence that animals on islands tend to be bolder than on the mainland, but effects on other personality traits go either way. The evidence for effects of insularity on cognitive abilities or style is highly circumstantial and very mixed. We conclude that our knowledge of the behavioural and cognitive responses to island environments remains limited, and we encourage behavioural biologists to make more use of these “natural laboratories for evolution”.

Genetics of behavioural evolution in giant mice from Gough Island

“…Organisms on islands behave differently from their mainland counterparts [1][2][3]. Island environments present novel resources, predation pressures and competition [4,5], leading to the evolution of new foraging strategies and activity patterns in island colonizers [6,7].…”

“…Behaviour of insular populations has long been of interest to evolutionary biologists. Darwin first used the term 'island tameness' [1] to describe the reduction in anti-predator behaviours commonly shown in insular organisms [2,3,8]. As part of the 'island syndrome' [9], insular populations show reduced aggression compared with mainland conspecifics [10][11][12].…”