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IN-STREAM AND WATERSHED PREDICTORS OF GENETIC DIVERSITY, EFFECTIVE POPULATION SIZE AND IMMIGRATION ACROSS RIVER-STREAM NETWORKS
Citation:
BLUM, M. J., E. R. WAITS, M. BAGLEY, S. A. JACKSON, F. B. DANIEL, F. H. MCCORMICK, D. J. CHALOUD, AND J. M. LAZORCHAK. IN-STREAM AND WATERSHED PREDICTORS OF GENETIC DIVERSITY, EFFECTIVE POPULATION SIZE AND IMMIGRATION ACROSS RIVER-STREAM NETWORKS. Presented at American Fisheries Society, San Francisco, CA, September 02 - 06, 2007.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Description:
The influence of spatial processes on population dynamics within river-stream networks is poorly understood. Utilizing spatially explicit analyses of temporal genetic variance, we examined whether persistence of Central Stonerollers (Campostoma anomalum) reflects differences in habitat quality and location within a highly modified urban watershed in southwestern Ohio, USA. While estimates of genetic diversity did not vary with habitat quality, evidence of weak but temporally stable genetic structure, location-dependent effective population sizes, and rates of immigration among sites suggest that persistence of C. anomalum within the watershed is largely attributable to source-sink dynamics driven by habitat heterogeneity. To better understand how location-dependent habitat heterogeneity may give rise to source-sink dynamics, we carried out a second study of C. anomalum in an adjacent basin to further compare estimates of genetic diversity, effective population size and rates of immigration to factors related to isolation, fine-grain and course-grain environmental variation. Mantel tests demonstrated a pattern of isolation-by-distance among sample locations, and stepwise regression identified factors associated with drainage density, isolation, fine-grain and coarse-grain environmental heterogeneity as predictor variables for estimates of effective population size and immigration rate. These results suggest that both watershed and in-stream conditions may influence population persistence, and indicate that further understanding of population dynamics within river-stream networks will likely come from additional studies that explore aspects of life history relative to spatial scale.