Zoologist Ben Evans, of McMaster University in Hamilton, and a team of researchers have discovered six new species of African clawed frog (Xenopus).  All six new species are relatively small (approximately 5 cm) and were found in West and sub-Saharan Africa.

African clawed frogs are highly aquatic, living in slow moving or stagnant water. Characteristically they have streamlined and flattened bodies, a vocal organ specialised for underwater sound production, lateral line organs, claws on the first three toes (inner) and fully webbed toes. African clawed frogs are widely used as a model organism for biological research including developmental biology, cell biology, toxicology, neuroscience and for modelling human disease and birth defects. They also provide a unique system for analyses of genome evolution and whole genome duplication in vertebrates, as most clawed frog species are polyploid ie they have multiple sets of DNA due to genome duplication.

The discovery of these six new species, increases the number of known clawed frog species to 29. Like most clawed frogs, the newly discovered species were all found to be polyploid. Genome duplication occurred several times in these new species; four are tetraploid and two are dodecaploid.

Evans and his team plan to travel to Ghana next year to gather further genetic information. If they are not already extinct, they hope to find the ‘lost ancestors’ of the newly discovered species; these are the species predicted to have existed in the past whose genomes became part of the polyploid species that exist today.

Evans said “For biodiversity conservation, it is paramount that we understand how much diversity there is and where it occurs. This is particularly crucial in the tropics, where global biodiversity is highest and in groups of organisms that have subtle physical differences between species and in which species diversity is therefore cryptic.”

This discovery has led to a greater understanding of species diversity in Xenopus and is important in answering broader questions related to genome duplication.

– Dr Vickie Flint

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