Australian researchers are part of an international group that has delved deep into the evolutionary past of termites.

The key pest termite species belonging to the genera Coptotermes, Reticulitermes and Heterotermes are all lower termites with common ancestry. Species from these genera are spread across every continent, apart from Antartica. However, the factors influencing their global distribution are poorly known. An international research group, including Dr Theo Evans and Dr Thomas Bourguignon (University of Sydney), has used mitochondrial DNA analysis to provide some understanding.

By analysing differences in the mitochondrial DNA from samples of different species collected from around the world, the group has estimated when on the evolutionary timeline the different species diverged and what geographic or dispersal events may have allowed this divergence to occur.

It appears Reticulitermes split from Heterotermes and Coptotermes around 60 million years ago. Reticulitermes, found in the Northern hemisphere, is a more ancient group that split away as the continents drifted apart.

In contrast, long distance ocean dispersal, by rafting in wood, is the most likely means by which Coptotermes and Heterotermes spread throughout the tropics. Coptotermes probably originated in Southeast Asia and spread throughout Indonesia, New Guinea and into Australia while Heterotermes could be considered as a pantropical genus.

All genera have continued spreading in more recent times as a result of human movement and trade around the globe.

The group concluded that land dispersal over land bridges explained four disjunctions (species divergence from an evolutionary point of view), oceanic dispersal by wood rafting explained eight disjunctions, and human introduction was the source of two recent disjunctions.

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