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Love in a cold climate: Understanding the dispersal and genetic structure of an abundant Antarctic topshell [Margarella antarctica]

Love in a cold climate: Understanding the dispersal and genetic structure of an abundant Antarctic topshell Margarella antarctica

Supervisors: Professor Bill Amos (Department of Zoology); Prof Lloyd Peck (BAS, lspe@bas.ac.uk); Dr Joseph Hoffman (University of Bielefeld, j_i_hoffman@hotmail.com) Dr Melody Clark (BAS, mscl@bas.ac.uk)

  

Understanding the drivers and barriers to species dispersal on ecological timescales is key to predicting future biodiversity patterns under climate change. Such data underpin our abilities to interpret long-term trends, evaluate the effectiveness of conservation measures and develop accurate ecosystem models. The persistence and productivity of a species within a changing ecosystem is influenced by a number of factors. At the physiological level, these include the relatively short-term exploitation of inherent population phenotypic plasticity to acclimate to the new conditions. This may then enable more permanent generational genetic adaptation to occur (Somero (2010) J Exp Biol. 213, 912). In terms of the potential for migration or ingression of useful genetic variants, connectivity and gene flow between populations are critical and these are influenced by life history traits, such as reproductive mode, age at first reproduction and number of propagules produced per event (Peck (2011) Mar Gen 4, 237). It is only by combining empirical genetic data and life history traits with spatially realistic models of dispersal and relating these to environmental conditions that insight is gained into the processes underpinning population dynamics over ecological and evolutionary timescales and enable the accurate prediction of future biodiversity patterns. In the marine environment, this approach has been termed “seascape genetics" (Galindo et al. (2006) Current Biol 16, 1622).

The seascape system we propose to investigate is based around the highly abundant Antarctic topshell, Margarella. antarctica. This is a brooding species with direct dispersal (via crawling) and a limited ability to move depending on local topography and substrate. A previous study of population genetics from Ryder Bay, adjacent to the NERC-BAS Rothera Research Station demonstrated a non-linear isolation by distance pattern (Hoffman et al. (2013) PLoS ONE 7:e32415).  This means that dispersal of this species, and the area over which gene flow can operate between closely linked populations, cannot be explained simply by distance, the situation is more complex. We have no data on the relative importance of currents, seabed topography and/or substrate in structuring populations. This project will address this lack of data with a more detailed population genetic analysis from samples already collected.