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Population Genetic Diversity and Fitness in Multiple Environments(BMCEB)
Citation:
MARKERT, J., D. M. CHAMPLIN, R. E. GUTJAHR-GOBELL, J. S. GREAR, A. KUHN, T. J. McGreevy, Jr, A. C. ROTH, M. BAGLEY, AND D. E. NACCI. Population Genetic Diversity and Fitness in Multiple Environments(BMCEB). BMC Evolutionary Biology. BioMed Central Ltd, London, Uk, 205(10):1-13, (2010).
Impact/Purpose:
This manuscript describes experimental studies that contribute to our understanding of the ecological risks associated with the loss of genetic diversity, in combination with changing environmental conditions. Here, we created lines of estuarine invertebrates that varied in genetic diversity and assessed genome wide diversity using molecular markers developed for the experimental species. Results of these studies demonstrate the reduced genetic diversity may exacerbate the effects of stressors, including those associated with changing environmental conditions. Our results demonstrate the value of controlled studies to predict effects of combined stressors including, potentially, climate on wild populations. General impacts from this contribution include improved understanding by managers and scientists of links between human activities, natural dynamics, ecological stressors and ecosystem condition.
Description:
When a large number of alleles are lost from a population, increases in individual homozygosity may reduce individual fitness through inbreeding depression. Modest losses of allelic diversity may also negatively impact long-term population viability by reducing the capacity of populations to adapt to altered environments. However, it is not clear how much genetic diversity within populations may be lost before populations are put at significant risk. Development of tools to evaluate this relationship would be a valuable contribution to conservation biology. To address theses issues, we have created an experimental system that uses laboratory populations of an estuarine crustacean, Americamysis bahia with experimentally manipulated levels of genetic diversity. We created replicate cultures with five distinct levels of genetic diversity and monitored them for 16 weeks in both permissive (ambient seawater) and stressful conditions (diluted seawater). The relationship between molecular genetic diversity at presumptive neutral loci and population vulnerability was assessed by AFLP analysis. There was a significant correlation between AFLP diversity and population fitness overall; however, AFLP markers performed poorly at detecting modest but consequential losses of genetic diversity. High diversity lines in the stressful environment showed some evidence of relative improvement as the experiment progressed while the low diversity lines did not. The combined effects of reduced average fitness and increased variability contributed to increased extinction rates for very low diversity populations. More modest losses of genetic diversity resulted in measurable decreases in population fitness; AFLP markers did not always detect these losses. However when AFLP markers indicated lost genetic diversity, these losses were associated with reduced population fitness.