​ Herpetology​

Research interests

I study life histories of southern African lizards, with the following syntheses in mind:

Evolution of viviparity in scincomorph lizards

Viviparity (life-bearing) has evolved on a number of separate occasions in scincomorphs, ranging from distant events to very recent ones. In the lizard family Cordylidae, for instance, a single divergence from oviparity (egg-laying) long ago resulted in a viviparous clade including almost all of the living species of the family. This event is poorly understood and accompanied or closely followed a major life-style transformation in the cordyliformes (i.e., from a terrestrial active foraging ancestor to a rock-dwelling sit-and-wait forager). Most members of the Scincidae, in contrast, are oviparous. But more than one transformation to viviparity have occurred within the family. Some viviparous scincid clades are formally recognized as genera, other genera include oviparous and viviparous members. There are even reports of 'bimodal' species, i.e. cases where some populations are oviparous while others are viviparous. We study key species (basal ones in the case of cordylids, and reproductively bimodal ones in scincids), which will hopefully throw considerable light on the evolution of viviparity in scincomorphs.

Evolution of placental nutrient transfer in scincomorph lizards

Scincids, specifically members of the genus Mabuya (Trachylepis), hold the key to only the second time in 300 million years in which an extreme form of placentotrophy (i.e., nutrient transfer over the placenta) has arisen among amniotes - the other being that in Mesozoic mammals. This nutritional pattern has been known to exist in South American Mabuya for some time, but the origin thereof remained unresolved until we described extreme placentotrophy in an African lineage. All New World Mabuya species are viviparous and placentotrophic, but African ones may be oviparous or viviparous, and embryos may feed on yolk or through placentotrophy. African Mabuya offers great potential to study not only oviparity to viviparity transformation in closely related taxa/populations, but also the evolution of viviparous placentotrophy.

Evolution of asynchronous breeding in lizards occurring in a fire-prone ecosystem

Some grass lizard and chameleon species occurring in fire-prone Fynbos vegetation (part of the Cape Floristic Kingdom) do not shelter from fire and suffer heavy losses during a burn. Rapid recruitment is required afterwards for the population to be restored by the time of the next fire (usually within the next 4-12 years). These fire-sensitive species display unusual life history characteristics suggestive of high recruitment potential. They also show prolonged or aseasonal breeding, and breeding activities are asynchronous among and between the sexes. We study covariation between life history characteristics and fire-caused environmental change, hoping to shed light on how and why asynchronous breeding evolved in these animals.

USA

Daniel G Blackburn (Trinity College, Hartford, Connecticut)

South Africa

William R Branch (Port Elizabeth Museum, Humewood)

P Le Fras N Mouton (Department of Botany & Zoology, University of Stellenbosch)