PARENT SESSION
Oral Session 14: Reptiles and Amphibians I: Salamanders and Newts.
Presiding: K McCoy
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 136.

Contrasting predator-prey interactions across spatial scales.

Urban, Mark ^*,1, ¹ Yale University, New Haven, CT

ABSTRACT- Spatial heterogeneity influences both ecological and evolutionary community dynamics. Mass effects models predict that relative rates of movement and exclusion via interspecific interactions determine species coexistence in metacommunities. However, coexistence also may be mediated by local adaptations to community interactions. Spotted salamanders (Ambystoma maculatum) breed in temporary ponds that vary in the distribution and abundance of predaceous marbled salamanders (Ambystoma opacum) across regional (hundreds of kilometers) and local (hundreds of meters) scales. I hypothesized that prey populations would evolve specialized defenses across regional but not local scales of increasing predator incidence assuming that gene flow among divergent habitats would swamp out local adaptations to A. opacum incidence. Common garden predation trials revealed that metacommunities with high interannual predator incidence suffered 30% less mortality than metacommunities with low predator incidence. However, at local scales, populations with higher predator incidence experienced up to twice the mortality rate as that experienced by populations with low predator incidence. I suggest that contrasting patterns of interaction strengths across local and regional scales may arise from an adaptive ontogenetic tradeoff between an initial increase in predation risk and growth to a predation-invulnerable size refuge. Evidence for the local differentiation of interspecific interactions supports the integration of ecological and evolutionary processes in metacommunity models and offers key insights on predicting local and regional extinctions in response to anthropogenic perturbations.

Key words: spatial ecology, predator-prey interactions, evolution