Population genetics of the calcifying algae, Corallina officinalis

In 2017 Teresa Vale conducted a master’s research project using SNP markers to analyse population genetic patterns of Corallina officinalis in the Northeast Atlantic. This is a follow-up to this previous project.

Abstract

Calcifying macroalgae are an integral part of marine communities but they are significantly vulnerable to ocean acidification caused by an increased uptake of CO2 emissions. Consequently, it is imperative that populations’ reactions to ocean acidification be examined by identifying their potential for physiological acclimatisation to environmental changes and/or evolutionary adaptation. Examination of populations across large geographic scales, over which ocean chemistry naturally varies, can reveal ‘adaptation hotspots’ where selection for tolerant genotypes prevails, and thus provide the opportunity to identify mechanisms underlying tolerance. The key to this approach is an understanding of the genetic variation within and between populations across a large geographic range. In the Northeast Atlantic (NE), Corallina species are important ecosystem engineers. They are distributed across large latitudinal gradients of ocean chemistry, and have been the focus of recent molecular research that has resolved several species concepts within the genus. In addition, Corallina species are model organisms to assess mechanisms of acclimation and adaptation to future change, which require the development of population genetic markers to facilitate such research. This project has used DNA extracted from collections made across the NE Atlantic (England, Scotland, Iceland, and Spain), to identify population genetic markers for Corallina officinalis through single nucleotide polymorphisms genotyping. These markers were used to assess population connectivity and genetic diversity for this important calcifying algae over the Northeast Atlantic. An isolation-by distance pattern was found among this species’ populations where Iceland was the most isolated population followed by Spain. However, within the UK fine-scale structuring was also observed, particularly in the South coast with Wembury Point being the most genetically distant population. Regarding climate change, Iceland and Spain may be at risk because they are less genetically diverse and more isolated in relation to the other populations, which might compromise their viability. In contrast, British populations present highly genetically diverse populations which offers them the possibility to adapt to environmental changes.

Citation

Vale, T (2017) Population genetics of the calcifying algae, Corallina officinalis. A thesis submitted for the partial fulfilment of the requirements for the degree of Master of Science in Wild Animal Biology at the Royal Veterinary College, University of London. Supervised by Chris Yesson & Juliet Brodie with the assistance of Steve Russell. (PDF)

Genetic cluster assignment for populations of Corallina officinalis.

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