Biomedical subjects

Mark C Urban

Publications and source records attributed to Mark C Urban.

3 recordsLinked to original sources

PubMed2006

Maladaptation and mass effects in a metacommunity: consequences for species coexistence.

Metacommunity theories predict multispecies coexistence based on the interplay between local species interactions and regional migration. To date, most metacommunity models implicitly assume that evolution can be ignored. Yet empirical studies indicate a substantial potential for contemporary evolution. I evaluate how evolution alters species diversity in a simulated mass-effects (sink-source) metacommunity. Populations inhabiting source habitats became locally adapted, while subordinate competitors became maladapted because of assumed ecological and phenotypic trade-offs between habitats. This maladaptation decreased and leveled relative abundances among subordinate populations. These two effects produced two regions of departure from nonevolutionary predictions. Assuming low proportional migration, maladaptation reduced local species richness via an overall reduction in reproductive rates in sink populations. With intermediate proportional migration, a greater absolute reduction of reproductive rates in intermediate competitors leveled reproductive rates and thereby enhanced local species richness. Although maladaptation is usually viewed as a constraint on species coexistence, simulations suggest that its effects on diversity are manifold and dependent on interpatch migration and community context. Hence, metacommunity predictions often may profit from an evolutionary perspective. Results indicate that modifications of community connectivity, such as might occur during habitat fragmentation, could elicit rapid shifts in communities from regions of high to low biodiversity.

Adaptation, Physiological↗

PubMed2006

Road facilitation of trematode infections in snails of northern Alaska.

Road disturbances can influence wildlife health by spreading disease agents and hosts or by generating environmental conditions that sustain these agent and host populations. I evaluated field patterns of trematode infections in snails inhabiting ponds at varying distances from the Dalton Highway, a wilderness road that intersects northern Alaska. I also assessed the relationships between trematode infections and snail densities and six environmental variables: calcium concentration, aquatic vegetative cover canopy cover temperature, pond size, and community structure. Presence of trematode infections and snail density were negatively correlated with distance from the highway. Of the pond characteristics measured, only calcium concentration and vegetation density declined with distance from road. However neither variable was positively associated with snail density or trematode presence. One potential explanation for observed patterns is that vehicles, road maintenance, or vertebrate vectors attracted to the highway facilitate colonization of snails or trematodes. Emerging disease threats to biological diversity in northern ecosystems highlight the importance of understanding how roads affect disease transmission.

Alaska↗

PubMed2006

Evolving metacommunities: toward an evolutionary perspective on metacommunities.

The metacommunity framework predicts that local coexistence depends on the outcome of local species interactions and regional migration. In analogous fashion, spatial structure among populations can shape species interactions through evolutionary mechanisms. Yet, most metacommunity theories assume that populations do not evolve. Here, we evaluate how evolution shapes local species coexistence and exclusion within the multiscale and multispecies context embodied by the metacommunity framework. In general, coexistence in joint ecological-evolutionary models requires low to intermediate dispersal rates that can promote maintenance of both regional species and genetic diversity. These conditions support a set of key mechanisms that modify patterns of species coexistence including local adaptation, gene storage effects, genetic rescue effects, spatial genetic subsidies, and metacommunity evolution. Multispecies extensions indicate that correlated selection can further alter the outcome of interspecific interactions depending on the magnitude and direction of correlations and shape of fitness trade-offs. We suggest that an evolving metacommunity perspective has the potential to generate novel predictions about community structure and function by incorporating the genetic and species diversity that characterize natural communities. In adopting such a perspective, we seek to facilitate understanding about the interactions between evolutionary and metacommunity dynamics.

Biological Evolution↗