Evolutionary resilience in the face of climate change

By Dr  Jennifer Pierson, Senior Ecologist

Climate change is no longer just a threat of the future that we need to plan for, it is happening now and already impacting biodiversity. Faced with this, what can we do to provide resilience to species and ecological communities?

Species’ adaptive capacity, in the context of climate change research, is their ability to avoid or adapt to climate change impacts. A species can move to a new location that is more suitable, if they have good dispersal capabilities and there are suitable corridors in the landscape for them to move through. Alternatively, a species can persist where they are. There are a few primary mechanisms that allow a species to persist in place:

– Evolutionary adaptation – genetic changes based on the selection of observable (phenotypic) traits that are heritable, and the focus of this article.

– Phenotypic plasticity – variation in expression of traits from the same genotype.

– Microhabitat buffering – use of local habitat features that protect an individual from exposure.

Wayne Lawler/AWC

From a management perspective, options are limited in what we can do to help species adapt to climate change.

One of the most powerful actions we can take is to give populations the best chance for natural evolutionary processes to help them cope with rapid environmental change. In other words, enabling evolutionary adaptation.

Evolutionary adaptation needs genetic variation for selection to act upon. Active management of genetic variation, and the ecological processes that interact with genetic variation, can give species a fighting chance to respond to change. In AWC’s Reintroduction Program, which spans 12 locations and 23 species, there are two main actions we are implementing to enable evolutionary adaptation by managing genetic variation.

Jane Palmer/AWC

First, when establishing new populations, we can put a mix of genetic variation into the population, or we can genetically supplement small, isolated populations that have lost variation. Species that have declined into small, isolated populations often have low genetic variation, however, different populations often have maintained a different range of genotypes than each other. By mixing individuals from different populations, we can try to maximise variation so that when changing conditions present themselves, there might be a genotype that helps individuals or their offspring survive better in new conditions.

The other action we can take is to try to maintain the range of genetically based phenotypic variation by exposing the species to as wide a range of selection pressures as possible. An evolutionary process called directional selection can shift phenotypes along the possible spectrum of a trait under environmental conditions. When there are multiple populations that are experiencing directional selection from different conditions, the process is called diversifying or divergent selection. An example of this is Darwin’s famous finches, where different island populations evolved different beak shapes based on what food was available.

AWC is actively translocating species to sites that experience different environmental conditions to try to ensure that potential genotypes and associated traits that may be important in the future are maintained in the species. More than half of the species involved in AWC’s Reintroduction Program have been translocated to more than one sanctuary or partnership area. For example, the iconic Bilby has been restored to six sites across four states and territories including Newhaven Wildlife Sanctuary in Australia’s arid zone. Places like Newhaven play an important role by exposing reintroduced species to intense desert conditions.

By combining these two actions – creating genetically mixed populations across a range of environmental conditions – we hope to provide reintroduced species with evolutionary resilience into the future under a range of climate conditions. AWC’s Reintroduction Program already makes a major contribution to the conservation of Australia’s threatened mammals and is embedding an eco-evolutionary approach to resilience as species face an uncertain future with a changing climate.

Read or download this full issue of Wildlife Matters here.