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Shrinking gene pool threatening leopards

http://www.iol.co.za/scitech/science/environment/shrinking-gene-pool-threatening-leopards-1.1710819

By Melanie Gosling

Cape Town – Between the wheat fields and sheep farms of the Overberg there is just enough natural land to support a population of free-ranging leopards.

But new research suggests these wild leopards may be doomed.

Wits doctoral student Jeannine McManus, working on leopard research for the Landmark Foundation, has monitored the leopard population in the Overberg between Bot River and Cape Infanta.

Using camera traps that are triggered by the animal’s movement to snap a shot of it, she estimates there are between nine and 14 leopards in that area.

The problem is these big cats – the last remaining free-ranging top predators in the region – have become restricted to increasingly small amounts of land as urbanisation and agriculture gobble up the wild spaces. The leopards are living in what amounts to “islands” of natural fynbos surrounded by farmlands and towns. While they can survive, the restricted living space means there is little way for the leopards in the Overberg to link up with leopards in other regions. The result is a shrinking gene pool, and genetic isolation can lead to extinction.

McManus has completed a genetic study on the leopards in the East and Western Cape, working from 40 samples.

“We can see where the gene flow took place, how one group is related to the next group – or whether it is related. What the samples gave us was a snapshot of the leopards in Overberg at this time and that showed that the gene flow is currently very low. There is not much genetic material flowing into the population and that’s not good because genetic isolation over time can cause extinction.”

What these findings highlight is the critical importance of having corridors that link wild areas and the habitats where the leopards can survive. In this way, animals can migrate and breed with animals from other areas, increasing the gene flow.

Does this mean increasing the amount of formally protected conservation land? McManus says while this would be good, it is not realistic.

“Only 20 percent of land is conserved in South Africa and 80 percent is privately owned, so if we are to conserve these animals, we have to work outside of the conservation areas. That’s what the Landmark Foundation has been doing, working with landowners on farms.

Between farms and on farms there is a significant amount of land which could be suitable for leopards.

“But it can’t be used because of lethal controls used by landowners, either traps or poisons. We work with farmers to reduce conflict between them and leopards. A lot of farmers are actually quite desperate for help and work with us.”

Much of this work includes providing information about alternatives to lethal controls, such as the use of livestock guardian dogs and livestock protection collars. By using these methods and doing away with traps and poisons, landowners open up corridors between protected areas and so link, genetically, populations not only of leopards, but of many wild animals. – Cape Times

melanie.gosling@inl.co.za