Acclimation and adaptation of seaweeds in a rapidly changing environment: a population genomic approach

Master Thesis subject (30 ECTS)
Oceans and Lakes
The marine realm represents some of the most ecologically and socioeconomically significant ecosystems on the planet. Unfortunately, coastal marine ecosystems, along with the goods and services they provide, are threatened by global climate change. Continuously increasing greenhouse gas emissions cause changes in oceanographic conditions such as temperature and pH, which in turn affect biological and social systems. Shifts in ocean characteristics likely act as stressors by inducing changes in life-history traits and physiological performance of organisms. The outcome of a changing climate is dependent on a combination of factors, including the rate and magnitude of climate change, the adaptive potential of the species (standing genetic variation, population structure, etc.), plastic and possibly also epigenetic responses. As a result of climate change (rising temperatures, unpredictability of the weather, etc.) populations may either shifts (climate tracking), adapt (evolve) or go extinct. The adaptive potential of populations is mainly determined by population size and available genetic diversity. However, the adaptability of spatially structured populations may also be affected by dispersal: positively by spreading beneficial mutations across subpopulations, but negatively by moving locally adapted alleles between locally adapted populations. Hence, there is a clear need to characterize spatial patterns of neutral as well as adaptive genetic variation in natural populations in order to understand the effects of local adaptation and dispersal on species persistence. This thesis focuses on the brown alga Dictyota. Natural populations of the selected organisms will be sampled in Europe. We will take advantage of a genotyping by sequencing (GBS) approach to develop genome-wide marker data from a sample of natural populations to infer demographic processes and find signatures of local adaptation. A technique that has been successfully applied in recent population genomic studies is restriction‐site‐associated DNA sequencing (RADseq) in conjunction with Illumina technology. Population genomic analysis will be carried out to examine geographic patterns of neutral and adaptive genetic diversity within and among populations, geographic population genetic structuring and gene flow, historical population dynamics, and loci under selection. Measures of neutral and adaptive genetic diversity will be estimated using population genomic techniques in combination with FST outlier analysis. This research will be realized through a cooperation of the Phycology Research and Marine Biology Research Groups (UGent) and the Department of Applied Mathematics, Biometrics and Process Control (UGent). The project combines fieldwork, lab experiments, molecular tools and modeling approaches.
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De Clerck
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Sofie De Rycke
Reference Number: RP-49011