Assessing genetic health of Victoria’s biodiversity for conservation planning

In less than 200 years since European settlement, much of Victoria’s natural environment has been dramatically transformed. A great deal of our natural habitat is now highly fragmented from clearing of land for agriculture, construction of roads and settlements, damming of rivers, and major changes in fire frequency and intensity.

As a result, much of our native flora and fauna now persists in isolated populations where individuals rarely if ever succeed in crossing barriers or open spaces that separate them from other populations.

This is a big challenge for conservation management.

Populations that are both isolated and small in number are at risk of developing genetic problems. The smaller and more isolated a given population is, the greater the risk.

To address this challenge, we are reviewing the current state of knowledge of population genetics for Victoria’s flora and fauna. This includes assessing the extent of population fragmentation for distinct species – whether natural migration of individuals is likely to still occur between what may appear to be separated patches of habitat.

This project is in partnership with DELWP and researchers at Monash University, and will cover all terrestrial vertebrate species native to Victoria – mammals, birds, reptiles, amphibians, and freshwater fish – along with a representative sample of our almost 3,300 species of native vascular plants.

Monitoring and managing the genetic health of wildlife populations is increasingly important for two reasons:

Firstly, populations that are small and isolated will inevitably lose genetic diversity over time. This is likely to compromise their potential to cope with or adapt to new diseases or environmental change – a growing concern in light of expectations for a warming climate over coming decades.

Secondly, for particularly small populations there is a greater chance of mating between closely related individuals. This leads to inbred offspring that are often quite unhealthy and have a poor ability to compete for limited resources. If isolation continues, extensive inbreeding can compromise entire populations and put them at risk of local extinction. In some cases, where all persisting populations of a species are now small and isolated from each other, the species as a whole may be at risk through this process – even if the number of individuals remaining in total is not critically small.

There is great potential to reverse or resolve such problems through management actions that restore natural gene flow that would have existed in the past – either through restoring connectivity between blocks of existing habitat, or in some cases, translocation of individuals between current populations.

However, our understanding of the scale of this issue, and the extent to which it is likely to worsen over time, is currently very limited – genetic problems in populations of biodiversity are rarely recognised through simple field observations and may not become apparent until it is too late for management intervention to be effective or realistic.

Despite the growing number of challenges for conservation in general, Victoria is very much taking a proactive approach to this issue and is the first jurisdiction in Australia to undertake such a project. Findings from the project are expected to inform better conservation planning decisions and enable more effective allocation of available resources… and we are excited to be playing a leading role.

Cover image: Photo by Andrew Weeks, Cesar Australia

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