Behaviour 2019
Behavioural plasticity in a native may be related to foraging resilience in the presence of an invader
Melinda L Keiller1, Laura K Lopez2, Kai C Paijmans1, Marian YL Wong1. 1School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia; 2Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States

Competition between invasive and native species can result in the exploitation of resources by the invader, reducing foraging rates of natives. However, it is increasingly recognized that multiple factors can enhance the resilience of native species competing for limiting resources with invaders. We examined the role of behavioural plasticity in interactions between a native Australian fish, Pseudomugil signifer, and a widespread invasive fish, Gambusia holbrooki. To determine whether P. signifer displays behavioural plasticity that may mitigate competition with G. holbrooki, we first quantified social behaviours and shoal cohesion for each species in single- and mixed species groups. Second, we compared the feeding rates of both species in these groups to ascertain if any modulation of social behaviours and cohesion related to foraging success. We found that some behaviours showed plasticity but shoaling and foraging remained inflexible. This variation in the degree of plasticity highlights the complexity of the behavioural response of a native and suggests that behavioural modulation and consistency may be related to sustaining foraging efficiency in the presence of an invader.