PARENT SESSION
Oral Session #4: Animal Population Ecology.
Presiding: L. Mitchell
Monday, August 5. 8:00 AM to 11:30 AM. Gila Meeting Room, TCC.

Population variation and multiple life history stage responses to predation in the stream salamander, Desmognathus quadramaculatus.

Miller, J. Richard^*,1, ¹ Department of Biology, Chapel Hill, NC

ABSTRACT- Adaptive phenotypic variation in response to predation is commonly demonstrated among amphibian larvae that occupy temporally and spatially discrete lentic habitats. Resultant morphologies and behaviors structure not only species interactions but also affect individual life history fitness correlates. I demonstrate through field and laboratory experiments and surveys that despite limited geographic separation within a contiguous lotic system, the alternation of a predation regime has influenced population adaptations to predaceous fish in the larvae and adults of the long-lived black-bellied stream salamander, Desmognathus quadramaculatus. Reciprocal transplant experiments demonstrate both naïve hatchling and older field-collected larvae allotopic to fish have reduced survivorship compared to populations and larvae syntopic to predators. In the presence of mottled sculpin (Cottus bairdi), larvae reared from egg clutches collected syntopic to predaceous fish grew less than larvae reared from fish-allotopic clutches, despite similar experimental densities. This response is not due to a differential competitive ability between population groups based on a multi-month intraspecific competition experiment. Laboratory behavioral assays reveal that the growth differential and limited survivorship is due to inaccurate threat recognition among allotopic larvae exposed to the olfactory presence of a predator, resulting in reduced foraging ability and escape response. Reproductive females syntopic to predaceous fish also respond by ovipositing larger clutches. Localized predation pressure during the larval stage therefore appears to operate as a selective agent on multiple life history stages to phenotypically differentiate sub-populations.

KEY WORDS: Desmognathus quadramaculatus, amphibian life history, predator-prey interaction, adaptive phenotypic variation