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A proposal: incorporating odonates into stream bioassessments using DNA barcodes
Citation:
PILGRIM, E. A proposal: incorporating odonates into stream bioassessments using DNA barcodes. Presented at Dragonfly Society of the Americas Annual Meeting, Sullivan, MO, June 19 - 21, 2009.
Impact/Purpose:
Biological resource conservation and management programs have benefitted greatly over the last decade from advances in population genetics research. The EPA, while having very similar goals to these programs, has yet to capitalize on the rapid advances in molecular population genetic methods. This research aims to evaluate the utility of population genetic measurements for describing the current condition and vulnerabilities of biological populations exposed to anthropogenic stressors. A key objective of the Clean Water Act is "to restore and maintain the chemical, physical, and biological integrity of the nation’s waters." Biological integrity is defined as the ability of an aquatic ecosystem to support and maintain a diverse, balanced, integrated, adaptive community of native organisms. A primary focus of this research effort is the molecular characterization of genetic diversity, a fundamental component of biodiversity and an important indicator of biological integrity. This research will assess and define biological integrity with scientific rigor, using population genetics as the basis for understanding biological diversity and functional organization. A completely developed indicator of genetic diversity will bring significant new data to the assessment of the biological integrity of aquatic resources and the sustainability of fish, invertebrate, and plant communities. These new data will be used to help characterize (1) appropriate ecological units (including cryptic species and biological populations) for assessment of fish and macroinvertebrate communities; (2) the inherent vulnerability of aquatic species to further exposure to stressors; (3) the relationship between genetic diversity and environmental condition; (4) temporal trends in the condition of fish and invertebrate populations; and (5) linkages between landscape-level stressors and population-level outcomes for aquatic organisms. By identifying the spatial scale at which individuals migrate and breed, measures of genetic diversity define biological populations, which are the most meaningful units for assessing species and communities. A significant loss of genetic diversity is detrimental to populations and affects their sustainability into the future. In the short term, reduced genetic diversity can contribute to inbreeding depression, lowering population fitness. In the long term, it reduces the population’s resilience because the population's genetic pool of potential responses to stress is restricted. The population’s lack of selectively propitious genes may lead to further population declines and eventual extirpation when faced with novel stressors or changes in stressor intensity. In addition, since past and present environments have shaped current levels of genetic diversity, molecular genetic markers are natural indicators of cumulative population exposure. Habitat degradation (chemical, physical, or biological), hybridization with introduced taxa, and habitat fragmentation have predictable effects on genetic diversity. Coupling of these molecular genetic data with quantitative environmental data and landscape data gathered through EMAP and other initiatives will allow powerful inferences to ecological condition and population responses to environmental stressors.
Description:
Bioassessment/biomonitoring uses the species found in an ecosystem as a way to measure the health of that ecosystem. Current methods rely mainly on mayflies, stoneflies and caddisflies as indicators for streams and rivers. Odonate larvae are also collected during sampling for bioassessment but are not part of any bioassessment metric, possibly due to the difficulty of identifying larvae to species. Recent advances using DNA barcoding for identifying odonate larvae to species could be utilized to incororate odonate species into biomonitoring programs.