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What is the context of this research?

In marine habitats, water movement often drives spatial distribution of marine species through mediation of larval and spore dispersal (Selkoe et al. 2008). Studies examining the effects of oceanographic features on gene flow can distinguish genetic lineages across spatial scales (Gordiano et al. 2007). Intertidal seaweeds, for example, are often characterized by short dispersal distances due to a lack of longevity in dispersal stages and low levels of water movement (Kreuger-Hadfield et al. 2013). For the red seaweed Mastocarpus stellatus, short dispersal distances in tandem with a broad geographic range provide an excellent opportunity to investigate an interesting biological question: What is the spatial scale of genetic structure for a low-dispersal organism?

What is the significance of this project?

Most animals that occupy broad geographic ranges exhibit high levels of population connectivity due to life cycles involving long-term larval durations that allow movement of individuals between populations as far as 100 km in some cases. For broadly distributed populations of organisms with short-distance dispersal, however, the rate of increasing genetic divergence in relation to spatial distance is yet to be understood. Examining patterns of gene flow among populations at a massive range of geographic distances (10 cm – 1000 km) will provide an understanding of the spatial scale of genetic diversity in organisms that are seldom studied in research focusing on genetic relationships.

What are the goals of the project?

The overarching goal of my research is to identify the spatial scale of genetic diversity in the red seaweed Mastocarpus stellatus. To achieve this goal, I will be examining genetic diversity between populations at three relevant spatial scales: fine-, medium-, and large-scale geographic distances. I have collected fronds of this species from 11 sites along the coasts of Maine and France for extraction of genomic DNA. For each collected individual, exact spatial positions (± 1 cm) have been recorded, and GPS coordinates are available for each site. After completion of the final procedural step of collecting genetic data at 16 microsatellite loci for each frond, I will compare geographic distances with genetic distances.