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Gene flow that hampers local adaptation can constrain species distributions and slow invasions. Predation as an ecological factor mainly limits prey species ranges, but a richer array of possibilities arises once one accounts for how predation alters the interplay of gene flow and selection. We extend previous single-species theory on the interplay of demography, gene flow, and selection by investigating how predation modifies the coupled demographicevolutionary dynamics of the range and habitat use of prey. We consider a model for two discrete patches and a complementary model for species along continuous environmental gradients. We show that predation can strongly influence the evolutionary stability of prey habitat specialization and range limits. Predators can permit prey to expand in habitat or geographical range or, conversely, cause range collapses. Transient increases in predation can induce shifts in prey ranges that persist even if the predator itself later becomes extinct. Whether a predator tightens or loosens evolutionary constraints on the invasion speed and ultimate size of a prey range depends on the predator effectiveness, its mobility relative to its prey, and the prey's intraspecific density dependence, as well as the magnitude of environmental heterogeneity. Our results potentially provide a novel explanation for lags and reversals in invasions. [ABSTRACT FROM AUTHOR]

Adaptive divergence among populations can result in local adaptation, whereby genotypes in native environments exhibit greater fitness than genotypes in novel environments. A body of theory has developed that predicts how different species traits, such as rates of gene flow and generation times, influence local adaptation in coevolutionary species interactions. We used a meta-analysis of local-adaptation studies across a broad range of host-parasite interactions to evaluate predictions about the effect of species traits on local adaptation. We also evaluated how experimental design influences the outcome of local adaptation experiments. In reciprocally designed experiments, the relative gene flow rate of hosts versus parasites was the strongest predictor of local adaptation, with significant parasite local adaptation only in the studies in which parasites had greater gene flow rates than their hosts. When nonreciprocal studies were included in analyses, species traits did not explain significant variation in local adaptation, although the overall level of local adaptation observed was lower in the nonreciprocal than in the reciprocal studies. This formal meta-analysis across a diversity of host-parasite systems lends insight into the role of both biology (species traits) and biologists (experimental design) in detecting local adaptation in coevolving species interactions. [ABSTRACT FROM AUTHOR]

Many natural populations are characterized by clinal patterns of adaptation, but it is unclear how gene flow and environmental gradients interact to drive such clines. We addressed this question by directly manipulating dispersal and productivity in an experimental landscape containing a microbial parasitoid, the bacteriophage T7, and its host, the bacterium Escherichia coli. We observed that the adaptation of parasitoids increased on hosts originating from lower-productivity communities in the absence of gene flow. However, adaptation decreased along the same productivity gradient with experimentally imposed gene flow of the host and parasitoid. This occurred despite relatively low rates of gene flow. [ABSTRACT FROM AUTHOR]