Implementing a rapid geographic range expansion - the role of behavior changes

Abstract

It is generally thought that behavioral flexibility, the ability to change behavior when circumstances change, plays an important role in the ability of species to rapidly expand their geographic range. Great-tailed grackles (Quiscalus mexicanus) are a social, polygamous species that is rapidly expanding its geographic range by settling in new areas and habitats. They are behaviorally flexible and highly associated with human-modified environments, eating a variety of human foods in addition to foraging on insects and on the ground for other natural food items. They offer an opportunity to assess the role of behavior change over the course of their expansion. We compare behavior in wild-caught grackles from two populations across their range (an older population in the middle of the northern expansion front: Tempe, Arizona, and a more recent population on the northern edge of the expansion front: Woodland, California) to investigate whether certain behaviors (flexibility, innovativeness, exploration, and persistence) have higher averages and variances in the newer or older population. We find that grackles in the edge population were more innovative and less exploratory, and that there were no population differences in flexibility (measured by reversal learning) or persistence (the proportion of trials participated in). Results elucidate that the rapid geographic range expansion of great-tailed grackles is associated with individuals differentially expressing particular behaviors. Our findings highlight the value of population studies and of breaking down cognitive concepts into direct measures of individual abilities to better understand how species might adapt to novel circumstances.

Behavioral flexibility is manipulable and it improves flexibility and innovativeness in a new context

“…Understanding how flexibility causally relates to other traits will allow researchers to develop robust theory about the mechanisms and functional impact of flexibility, and when to invoke it as a primary driver in a given context, such as a rapid geographic range expansion. Indeed, we are already in the process of testing the latter hypothesis by conducting cross-population research on great-tailed grackles to test whether a population on the range edge is more flexible (Logan et al, 2023b). That we were able to manipulate flexibility, which had causal effects on flexible behavior in a different context (multi-access box) as well as a different cognitive ability (innovativeness), demonstrates that flexibility manipulations could be useful in training individuals of other species in how to be more flexible.…”