Taxonomy & Evolution

Climate driven population divergence and future extinction risk in wild tomato

Climate change is generally thought to affect plant distribution by reducing the suitability of a species to its environment and diminishing its effective range. Modelling can be used to assess potential changes in distribution however classical distribution modelling assumes that a species is a homogeneous group having one optimal niche. Given the undeniable evidence of differential local adaptation of diverse populations within a species, results from such modelling can be misleading. In fact, some recent studies have even shown locally adapted populations of a species to respond to climate change differently. Incorporating population differentiation into these models could inform us on how local populations of species form across large geographic regions and allow us to predict potential implications of future environmental change on these populations.

S. pimpinellifolium originated from Ecuador and its three genetic groups were diverged southwards. Image credit: Lin et al.

In a new study published in AoBP, Lin et al. propose a hypothesis that Solanum pimpinellifolium, a wild relative of tomato, originated from Ecuador and diverged southwards into genetically differentiated groups in Peru. They also suggest that during the divergence, the niche of southern populations of S. pimpinellifolium became increasingly associated with drought and cold. Using environmental, geographic and localised population genetic data in their modelling, the authors showed that under anthropogenic climate change the ancestral group in Ecuador may maintain or even expand its distribution. On the other hand, the group in southern Peru could see its distribution shrink. The authors conclude that there could be distinct future fates among genetic groups of this species that may be driven by their unique environmental adaptations. They do however also state that whilst high genetic diversity can be treated as a buffer that reduces the instant impact under changing environment, this does not guarantee the future fate of a population.

This article was published as part of the AoBP Special Issue entitled The Ecology and Genetics of Population Differentiation in Plants.