Can Cognitive Ability Give Invasive Species the Means to Succeed? A Review of the Evidence

Abstract

Invasive species are a global conservation problem that have an enormous economic cost. Understanding the attributes of invasive species and what makes them successful at colonizing and flourishing in novel environments is therefore essential for preventing and ameliorating their negative impact. Learning ability and behavioral flexibility-the ability to adjust behavior flexibly when conditions change including to learn to solve novel problems or existing problems in a novel way, are thought to play a key role during invasions although cognitive ability is rarely considered in studies of invasive species. We begin by reviewing the evidence that flexible learning and problem solving can influence invasion success in both invertebrates and vertebrates. We also review brain size as an index of cognitive ability with respect to invasion success. We then focus on the specific attributes of cognition that are likely to be important for species entering novel environments as they learn the location of resources (e.g., food, shelter), and as they encounter and interact with conspecifics, heterospecifics, and potential predators. We suggest that enhanced spatial learning ability in conjunction with behavioral flexibility are likely to be adaptive. Furthermore, good memory retention and the ability to learn from others (both conspecifics and heterospecifics) are beneficial. Finally, we suggest future directions for studying the link between cognition, fitness, and invasion success. Studies of closely related "invasive" and "non-invasive" species, as well as invasive populations and their source, should provide important baseline information about the potential role of cognitive ability in determining invasion success. We also advocate an experimental approach. In particular, we borrow methods from experimental evolutionary ecology. We suggest that experimental studies in which potential invasive species can be assayed for behavior and their cognitive ability measured prior to population-level release on small islands will help inform us about the potential role of cognitive ability in determining the fitness of invasive species. The idea that cognitive ability may determine invasion success is only now starting to gain traction. This is a rich field worthy of further study that will help us better understand what makes a successful invasive species.

Animal Cognition in an Urbanised World

“…Like any animal in an evolutionarily novel environment, urban-dwelling animals must solve a similar set of problems including finding food, shelter and breeding sites, and avoiding danger. Gathering information from the environment reduces uncertainty (Dall et al, 2005), and it is therefore expected that cognitive mechanisms that facilitate the acquisition and use of information for decision-making are favoured where they allow animals to flexibly adjust their behaviour to novel ecological conditions (Sol et al, 2013;Szabo et al, 2020). However, the specific informational challenges encountered in novel environments, and the role of cognition in overcoming these challenges, depends on how the new environment differs from the ancestral environment.…”

“…Indeed, it is vital that the informational challenges associated with urban living are compared to those associated with non-urban habitats, in order to predict differences in selection pressures acting on cognitive traits. It would be particularly interesting to compare the informational challenges of urban habitats to other novel, but non-urban habitats, in order to determine whether particular cognitive abilities confer benefits across contexts (Sol et al, 2020;Szabo et al, 2020).…”

“…Indeed, many of the empirical studies investigating the cognitive performance of urban exploiters or invasive species have found that persistence, motor diversity or general activity levels best predict performance in the task (e.g., Bezzina et al, 2014;Griffin and Diquelou, 2015;Daniels et al, 2019). Furthermore, studies have yet to establish a direct link between innovation or problem-solving abilities and fitness of animals in urban or otherwise novel environments (Szabo et al, 2020), although the fitness value of these abilities has been investigated in "natural" habitats (e.g., Cole et al, 2012). Given that the cognitive bases of problem-solving and innovation are poorly understood and likely to differ substantially between species and contexts (Thornton and Samson, 2012;Thornton et al, 2014;van Horik and Madden, 2016), there is a need for experimental studies to unpack the cognitive processes involved in innovation and problem-solving, quantify variation in performance in specific cognitive processes such as neophobia, associative learning and generalisation, and investigate the fitness consequences of this variation (Thornton et al, 2014).…”

“…Cognitive abilities that determine animals' ability to acquire, store, and process information from the urban environment are likely to influence the potential for behavioural adjustments. The role of cognition in facilitating or inhibiting adaptation to novel environments has attracted increasing research attention in recent years (Sol et al, 2020;Szabo et al, 2020). In the context of urbanisation, a growing number of studies compare urban-rural differences in cognitive performance and neural architecture (Sol et al, 2005(Sol et al, , 2013Snell-Rood and Wick, 2013;Griffin et al, 2017a).…”

“…In the context of urbanisation, a growing number of studies compare urban-rural differences in cognitive performance and neural architecture (Sol et al, 2005(Sol et al, , 2013Snell-Rood and Wick, 2013;Griffin et al, 2017a). To date, these studies paint a complex picture, highlighting substantial variation within and between species, and much remains to be learned about the potential ecological and evolutionary consequences of cognitive variation in novel environments more generally (Szabo et al, 2020) and in urban environments specifically (Sol et al, 2020). In this review, we argue that our ability to identify the importance of cognition in facilitating city life would be greatly enhanced by identifying the specific informational challenges faced by urban-dwelling animals, how these informational challenges differ from those of the non-urban or ancestral environment, and how specific cognitive processes facilitate (or constrain) the ability of animals to overcome these challenges.…”