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In this paper, we use an integrodifference equation model and pairwise invasion analysis to find what dispersal strategies are evolutionarily stable strategies (ESS) when there is spatial heterogeneity in habitat suitability, and there may be seasonal changes in this spatial heterogeneity, so that there are both advantages and disadvantages of dispersing. We begin with the case where all spatial locations can support a viable population, and then consider the case where there are non-viable regions in the habitat that makes dispersal really necessary for sustaining a population. Our findings generally align with previous findings in the literature that were based on other modeling frameworks, namely that dispersal strategies associated with ideal free distributions are evolutionarily stable. In the case where only part of the habitat can sustain a population, a partial occupation ideal free distribution that occupies only the viable region is shown to be associated with a dispersal strategy that is evolutionarily stable. As in some previous works, the proofs of these results make use of properties of line sum symmetric functions, which are analogous to those of line sum symmetric matrices but applies to integral operators. 

Consumers must track and acquire resources in complex landscapes. Much discussion has focused on the concept of a ‘resource gradient’ and the mechanisms by which consumers can take advantage of such gradients as they navigate their landscapes in search of resources. However, the concept of tracking resource gradients means different things in different contexts. Here, we take a synthetic approach and consider six different definitions of what it means to search for resources based on density or gradients in density. These include scenarios where consumers change their movement behavior based on the density of conspecifics, on the density of resources, and on spatial or temporal gradients in resources. We also consider scenarios involving non-local perception and a form of memory. Using a continuous space, continuous time model that allows consumers to switch between resource-tracking and random motion, we investigate the relative performance of these six different strategies. Consumers’ success in matching the spatiotemporal distributions of their resources differs starkly across the six scenarios. Movement strategies based on perception and response to temporal (rather than spatial) resource gradients afforded consumers with the best opportunities to match resource distributions. All scenarios would allow for optimization of resource-matching in terms of the underlying parameters, providing opportunities for evolutionary adaptation, and links back to classical studies of foraging ecology. 

Trait‐mediated behavioral responses to other species, especially predators, can have important effects on the dynamics of populations. One effect is to modify dispersal patterns, which in turn can modify population dynamics and species interactions. We model a situation where a focal population responds to disturbances created by the harvesting of another population by increasing the rate of random dispersal by individuals. The model shows that in some situations this effect can result in the extinction of the focal population, even if it is not itself subject to harvesting. This observation suggests that it may be desirable to consider trait‐mediated effects when assessing the possible impacts of harvesting on conservation.

Be aware that harvesting a given crop or population can affect other populations because of their behavioral responses to the harvesting activity, even if it does not directly impose mortality on those populations or change their interactions with other species.

A way that harvesting activity can affect nonharvested populations is to increase their dispersal rate. Managers should be aware that this has the potential to cause extinction in some situations even if no other effects of harvesting are present.

For some populations, harvesting resources with which they interact or share an environment could in principle cause both direct and indirect effects, which could combine to have a different, perhaps greater, impact than either one would have separately.