Viviparity in South African lizard
Live-bearing lizards from South Africa!!!
A first for the Southern Hemisphere and Africa
Many reptiles have independently evolved viviparity (live-bearing) as a means of reproduction. In the true lizards (Lacertidae), this is most commonly known in the widespread Eurasian lizard (Zootoca vivipara). However, no viviparous lacertids have been documented outside of Europe and Asia. The Mountain lizards (Tropidosaura) are an interesting genus of lizards endemic to South Africa and Lesotho. The genus is currently comprised of four species, however once the taxonomy of the species has been addressed, this will likely change. All members of Mountain Lizards have been considered to be live-bearing, as with all other African lacertids.
This was until a large gravid female Essex's mountain lizard (Tropidosaura essexi) was dissected and contained well-developed embryos. All Essex's mountain lizards showed means of live-bearing, while other members of the genus contained eggs. These findings illustrate yet another independent case of the evolution of viviparity among reptiles.
Below are two species of Mountain Lizards, both closely related to Essex's mountain lizard, however, are egg-laying (oviparous).
Natal Mountain Lizard (T. montana natalensis)
Ranger’s Mountain Lizard (T. montana rangeri)
Typical habitat of Essex's mountain lizard (Tropidosaura essexi). South Africa can be seen on the slopes, while Lesotho is located over the escarpment.
A female Essex's mountain lizard (Tropidosaura essexi) that is likely gravid, given her size. This female would give birth in the summer months in the high altitude grasslands of the Drakensberg
“ Our finding that T. essexi is indeed viviparous, despite published records indicating otherwise, reveals just how poorly the life history of T. essexi is known. This case serves as a typical example for many species of herpetofauna in Africa and demonstrates the dearth of life history data on herpetofauna in general. In addition to informing conservation decisions and management, these findings inform several theoretical aspects of the biology of squamates and reveal opportunities for future research.” Nicolau et al. (2022)
Essex's Mountain Lizard (T. essexi) left and Common Mountain Lizard (T. montana natalensis) right. These two species are morphologically similar. Both species are found in the Drakensberg escarpment.
If you would like to read more about these findings, see Nicolau et al. 2020 and request the full text, or email me at nicolauecology@gmail.com
Gary K Nicolau, Emily A Jackson, Adriaan Jordaan & Graham J Alexander (2022) Tropidosaura essexi Hewitt, 1927 (Reptilia: Lacertidae) is live bearing: the only viviparous African lacertid,African Journal of Herpetology
https://doi.org/10.1080/21564574.2021.2019839
