A pinboard by
Pragya Chaube

Ph.D. student, University of Sheffield


The ability of a species to adapt to the local environment is one of the key processes that generate and maintain biodiversity. In the absence of adaptation, the changing environment drives the species to extinction. The process is fuelled by divergent selection pressures that act on the populations in distinct environments. The selection acts on the inherent variations present in the population; with the traits which render the individuals with better survivability and reproduction prevailing in that population under that environment. Over generations, this cause accumulation of differences between populations in different environments. The migration of individuals from one population to other, which are under different selection pressures, opposes the selection as it increases gene flow. At the same time, migration increases variation in the populations, a key requirement for selection. This is a poorly understood mechanism that finds practical implications in biodiversity management- when is it advantageous to facilitate migration as opposed to local adaption? The study system of the marine snail Littorina saxatilis lets us examine this poorly understood interaction between dispersal and adaptation in the wild. The two diverging ecotypes of the snail can be observed across Europe on the rocky shores. Few meters apart, the two ecotypes live in distinct habitats and face different selection pressures- one of crab predation, other of wave action. To adapt, these ecotypes have acquired traits which make them structurally and behaviourally distinct. Despite this, these ecotypes meet in small contact zones and hybridize. These hybrid zones are natural laboratories which allow the ecologists to study which traits are diverging and facilitating adaptation. Theory suggests that adaptation is dependent on the genetic architecture of the traits underlying divergent selection. My research is to elucidate the genetic architecture of such divergent traits in this species. I have been able to identify the principal traits under selection and through association analysis in multiple contact zones on the western coast of Sweden, identify what are the genes associated with these traits. Principles developed through this study can be extrapolated to common species that provide ecosystem services.