Ecological linkages between community and genetic diversity in zooplankton among boreal shield lakes

Ecological linkages between species diversity in communities and genetic diversity in populations have potential to influence the assembly of communities in habitats recovering from human disturbance, but few studies have attempted to synthesize relationships between these levels of biological organization, especially for locally adapted species. No such studies have been done in freshwater ecosystems despite the plethora of environmental stressors plaguing aquatic communities around the world. We present the first study to test (1) whether diversity and dissimilarity among communities and populations of a locally adapted species are correlated and (2) whether communities and population haplotypes respond differently to environmental selection and spatial structure of habitats. We used a fragment of mitochondrial DNA (mtDNA) belonging to the gene cytochrome oxidase subunit I (COI) as a neutral tag to discriminate among different population haplotype variants. In boreal lakes with different histories of exposure to anthropogenic acidification, diversity and dissimilarity metrics for crustacean zooplankton communities and locally adapted populations of an abundant and broadly distributed calanoid copepod species, Leptodiaptomus minutus, did not correlate. This discord was likely because zooplankton communities responded more strongly to acidity and acidity-related environmental variables than spatial structure of lakes, whereas the distribution of L. minutus haplotypes was more strongly governed by spatial structure of lakes than environmental selection. Although spatial structure was the dominant driver of haplotype structure among L. minutus lake populations, there were similarities in the types of environmental variables that influenced the distributions of species in communities and haplotypes in populations. How haplotype diversity among populations relates to community diversity depends on the relative influence of spatial structure of habitats and selection at each of these scales of biological organization.