Lizards, fire and genes

Fire mosaics are often maintained in landscapes to promote successional diversity in vegetation. However, there is little understanding of how this will affect ecological processes in animal populations such as dispersal and social organization. To investigate these processes, Annabel Smith and colleagues conducted a landscape genetics study of two woodland lizard species: a tree dragon (Amphibolurus norrisi) and a skink (Ctenotus atlas). Dragons have a more complex social and territory structure than skinks, so fire might have a greater impact on their population structure and thus genetic diversity.

The researchers found that genetic diversity increased with time since fire in the skink and decreased in the tree dragon. For the skink, this might reflect its increasing population size after fire, though the researchers could not detect increased gene flow that would reduce the loss of genetic diversity through genetic drift. Using landscape resistance analyses, they found no evidence that post-fire habitat succession or topography affected gene flow in either species and we were unable to distinguish between survival and immigration as modes of post-fire re-establishment.

In the tree dragon they detected female-biased dispersal, likely reflecting its territorial social structure and polygynous mating system. The increased genetic diversity in the tree dragon in recently burnt habitat might reflect a temporary disruption of its territoriality and increased male dispersal, a hypothesis that was supported with a simulation experiment.

These results suggest that the effects of disturbance on genetic diversity will be stronger for species with territorial social organization.


Reference 

Smith AL, CM Bull, MG Gardner and DA Driscoll (2014) Life history influences how fire affects genetic diversity in two lizard species. Molecular Ecology 23: 2428-2441.

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