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Population genetics and demographic resilience in three aquatic invertebrates

Macdonald, Hannah 2016. Population genetics and demographic resilience in three aquatic invertebrates. PhD Thesis, Cardiff University.
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Freshwater environments are threatened worldwide by external stressors and biodiversity decline, with major implications for ecosystem resilience. The genetic consequences so far have been neglected, especially for freshwater invertebrates, though their abundance, diversity, ease of sampling and functional importance renders them ideal candidates for genetic appraisal. For three freshwater invertebrates (Amphinemura sulcicollis, Isoperla grammatica and Baetis rhodani) novel microsatellite markers were developed so that genetic structure, and genetic diversity could be assessed throughout upland Wales. The aim was to investigate dispersal and the genetic response to environmental stressors. Genetic diversity in these species was compared to species diversity across whole macroinvertebrate assemblages to investigate what factors might cause a correlation between these fundamental levels of biodiversity. The demographic history of each species was also investigated with the aim of assessing whether reduced genetic diversity was due to bottlenecks and more broadly, what this indicates in terms of the populations’ resilience. Species differed in their genetic structure and genetic diversity. All three species showed effective dispersal and geneflow, with each species displaying panmixa across catchments in southern and mid-Wales. However, A. sulcicollis and I. grammatica revealed genetic isolation and reduced genetic diversity at specific northern sites. Genetic and species diversity were correlated positively only in A. sulcicollis, where isolation combined with a common driver were the likely cause. There was evidence of recent bottlenecks in all three species. All these results could be explained by an underlying genetic response to post-industrial acidification: reduced genetic diversity correlated significantly with acidity for A. sulcicollis, while reduced species diversity and genetic bottleneck signatures was consistent with chronic and episodic acidification across the Welsh region. Overall, these results show how a positive correlation between species and genetic diversity can never be assumed, and illustrate how assessments of genetic health expand insights available from traditional biodiversity assessment.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
Funders: The President Research scholarship from Cardiff University, NERC DURESS project
Date of First Compliant Deposit: 9 May 2017
Last Modified: 04 Jun 2017 09:49

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