Exploratory behaviour and transmission of information between the invasive guppy and native Mexican topminnows

Sociability in animals provides benefits such as reduced predation risk and increased foraging efficiency. During the early stages of invasion, individuals are often vulnerable as part of a small population (Allee effects); associations with native heterospecifics could mitigate some of the disadvantages of small population size and thereby increase the chances of establishment success. Here we explored two potential benefits of heterospecific association to guppies, Poecilia reticulata, a very successful invasive species. We first investigated whether guppies can exploit visual cues from morphologically similar heterospecific individuals as effectively as those from conspecifics. We next tested whether willingness to explore an unfamiliar environment depends on whether guppies are accompanied by conspecifics or heterospecifics. Our results show that guppies can acquire information on food availability from another species, as well as from conspecifics. We also found that guppies engaged in exploratory behaviour more quickly if the habitat had plants in it, and were more likely to associate if it was unstructured; there was, however, no difference in the frequency with which the focal fish was accompanied by a conspecific or a heterospecific individual. These results show that guppies respond to these heterospecifics as they do with conspecifics. Our study reveals some of the traits that could make an invader successful and potentially help to identify species with a higher potential to become established outside their native range.