Replaying the evolutionary tape: the genetics of parallel adaptation

The Hodgins lab is currently seeking outstanding PhD candidates interested in studying plant ecological genomics (www.hodginslab.com). Our laboratory studies the genetic basis for adaptation in plants. We are particularly interested in using introduced species as a model for studying rapid adaptation. We also study adaptation to climate in forest trees and plant domestication. To address evolutionary questions relating to these topics, we use a combination of genomics, ecological fieldwork and experimental approaches.

Melbourne is diverse and thriving city with a desirable climate. It is one of the most livable cities in the world and is a cultural and recreational hub.

Monash is a member of the Group of Eight, a coalition of top Australian universities recognized for their excellence in teaching and research. The School of Biological Sciences is a dynamic unit with strengths in both ecology and genetics and the nexus between these disciplines.

Please send your CV, a transcript, a brief statement of your research interests and the contact details of two referees to [Email Address Removed].

Potential project description

Repeated adaptations to similar selective environments certainly occur. The recurrent evolution of pesticide resistance, as well as parallel geographic patterns of flowering time invasive plants stand out as classic case studies. Given the involvement of chance and the myriad of possible ways a species could evolve, why are the phenotypic outcomes often so consistent? Is adaptive evolution of phenotypes to similar environments always highly repeatable, or is our attention diverted to a biased selection of examples? Even if similar phenotypes evolve independently in different geographic regions, are they as alike as they appear: could different genetic mechanisms be responsible in some cases?

This project aims to gain insight into the repeatability of local adaptation, and the genetic constraints that may underlie this, using a set of replicated range expansions along major climatic gradients. The annual plants Cakile maritima and Cakile edentula (both 2n=18) evolved along parallel gradients of great climatic range (over ~30º of latitude) on either side of the North Atlantic in a narrow coastal habitat. They have since undergone human-assisted introductions and subsequent range expansions in multiple regions (e.g. western North America, Australia, New Zealand, Japan, South America). Thus, we can compare local adaptation during range expansions differing in evolutionary timescales (millennia for post-glacial spread in native ranges vs. decades in their exotic ranges) in the same species as well as between species. Moreover, each invasion arises from unique combinations of source and recipient climates. Adaptation is potentially ongoing, since they are still expanding their exotic geographic ranges. These species afford us an exciting opportunity to examine fundamental evolutionary hypotheses about the genetic basis of adaptation outside the laboratory, in ecologically realistic experimental conditions.