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Alexander Herp Lab

The Alexander Herp Lab is a research lab based within the School of Animal, Plant and Environmental Sciences at the University of the Witwatersrand, Johannesburg, South Africa



The lab currently consists of: 

Professor Graham Alexander (Head of the lab)

Head of Lab
Professor Graham Alexander’s current interests are focused on the importance of snakes as predators. Snakes have an impressive factorial scope in their ingestion rates of prey, and this is likely to translate into a large and immediate functional response to changes in the abundance of their prey. Thus, snakes may be important and underappreciated ecosystem stabilisers in some environments, but this has not been investigated to any extent. Graham is currently conducting research to quantify these ideas and has worked on Southern African Python and Puff Adders for several years. He has recently started collaborating with Dr Bryan Maritz to study Cape Cobras and Boomslang, and their predatory impact on Sociable Weavers in the Kalahari. He also heads the Alexander Herp Lab, and carries a heavy undergraduate and postgraduate teaching load. He sits on the Viper Specialist Group, and on the Boa and Python Specialist Group for the Species Survival Commission of the IUCN. He is currently the Chairman of the Herpetological Association of Africa and the Chairman of the Editorial Committee for the African Journal of Herpetology. He sits on SANBI’s Alien Risk Analysis Review Panel and is a main member of the Steering Committee for the IUCN Southern African Regional Reptiles Specialist Group. He is also a taxon expert for SANBI redlisting initiatives and Threatened species work and consults for the Department of the Environmental Affairs in the formulation of AIS National Lists for NEMBA.

Dr Xavier Glaudas (Post-doctoral fellow)

Post-doc fellow
Xavier studies animal and behavioral ecology, with the goal of observing what animals do in nature and the reason they do it.

Shivan Parusnath (PhD student)

PhD student
Shivan is doing research on the population genetics of the Sungazer (Smaug giganteus), a Threatened South African lizard. He is also interested in understanding the illegal reptile trade and how it affects southern African species.

Mimmie Kgaditse (PhD student)

PhD student
Mimmie Kgaditse is currently studying what determines how southern African snakes are distributed, and their likely fate in a rapidly changing world.

Ashadee Kay Miller (PhD student)

PhD student
Ash's current research endeavour focuses on elucidating the mechanism underlying the Puff Adder's (Bitis arietans) extraordinary chemical crypsis, and to what extent this phenomenon may be present within the Viperidae.

Bevan Dell (PhD candidate student)

PhD student
Bevan is involved in researching differences in digestive physiology between ambush and active foraging snakes and how these differences affect snake ecology.

Ishvara Singh (MSc student)

MSc student
Ish's research focuses on the scale microarchitecture of southern African snakes in a functional ecological context.

Wade Stanton-Jones (MSc student)

MSc student
Wade is doing research on the population ecology of the Sungazer (Smaug giganteus). He is also interested in the thermal biology of reptiles. 

Hiral Naik (MSc student)

MSc student
Hiral is doing research on the evolution of feeding in snakes and factors that influence their diet.

Bianca Fizzotti (MSc student)

MSc student
Bianca is researching the effect of roads on Puff Adder (Bitis arietans) movement. She is also interested in the adaptive morphology of snakes.

Alexandra Evans (MSc student)

MSc student
Alexandra is investigating how reptile community composition is associated with habitat structure in Madagascar, and how this could relate to a species' foraging mode and threat status. She is also doing research on the dental morphology and behaviour of the Mole snake (Pseudaspis cana).

Melissa Petford (MSc sudent)

MSc student
Melissa is researching the microhabitat requirements of rupicolous reptiles of the Soutpansberg. Her research has a particular emphasis on the coexistence strategies of two Soutpansberg endemic Lygodactylus species, the Cryptic Dwarf Gecko (Lygodactylus incognitos) and the Soutpansberg Dwarf Gecko (Lygodactylus soutpansbergensis).


Publications from the last 10 years

Peer-reviewed Journals

  1. Glaudas, X., and G.J. Alexander In press. Food supplementation affects the foraging ecology of a low-energy, ambush-foraging snake. Behavioral Ecology and Sociobiology
  2. Glaudas, X., and G.J. Alexander In press. A lure at both ends: aggressive visual mimicry signals and prey-specific luring behavior in an ambush-foraging snake. Behavioral Ecology and Sociobiology
  3. Glaudas, X., Kearney, T.C., and G.J. Alexander. In press. To hold or not to hold? The effect of prey type and size on the predatory strategy of a venomous snake. Journal of Zoology (London).
  4. Glaudas, X., Kearney, T.C., and G.J. Alexander. In press. Museum specimens bias measures of snake diet: a case study using an ambush-foraging snake, the puff adder (Bitis arietans) Herpetologica
  5. Parusnath, S., Little, I. T., Cunningham, M. J., Jansen, R., & Alexander, G. J. 2017. The desolation of Smaug: The human-driven decline of the Sungazer lizard (Smaug giganteus). Journal for Nature Conservation 36: 48-
  6. Maritz, B., M. Kgaditse & G.J. Alexander. 2016. Snake body size frequency distributions are robust to the description of novel species. Ecosphere7: e01348.
  7. Tolley, K.A., G.J. Alexander, W.R. Branch, P. Bowles & B. Maritz. 2016. Conservation status and threats for African reptiles. Biological Conservation BIOC-06765.
  8. Aust, P., N. Van Tri, D. Natusch & G.J. Alexander 2016. Asian snake farms: conservation curse or sustainable enterprise? Oryx doi:10.1017/ S003060531600034X
  9. Williams, V.L., T.J. Moshoeu, & G.J. Alexander. 2016. Reptiles sold as traditional medicine in Xipamanine Market, Maputo, Mozambique. South African Journal of Science 112: 20150416.
  10. Maritz, B. & G.J. Alexander. 2016. Scale-dependent orientation in movement paths: a case study of an African viper. Ethology 122: 207-214.
  11. Miller, A.K. Maritz, McKay, S. Glaudas, X. & G.J. Alexander. 2015. An Ambusher’s Arsenal: Chemical Crypsis in the Puff Adder (Bitis arietans). Proc. R. Soc. B 282: 20152182.
  12. Alexander, G.J. & B. Maritz. 2015. Sampling interval significantly impacts the estimation of movement parameters in African snakes. Journal of Zoology (London) 297: 309-318.
  13. Botts, E.A., B. F.N. Erasmus & G.J. Alexander. 2015. Observed range dynamics of South African amphibians under conditions of global change. Austral Ecology 40: 309-317.
  14. Miller, A.K., Erasmus B.F.N. & G.J. Alexander. 2014. Digestive efficiencies are independent of gut transit times in Rainbow Skinks (Trachylepis margaritifer). Comparative Biochemistry and Physiology A 175:110-114.
  15. Thomas, R.L, L. Owen-Smith, D.C. Drake & G.J. Alexander. 2014. Restoring breeding habitat for Giant Bullfrogs (Pyxicephalus adspersus) in South Africa. African Journal of Herpetology 63: 13-24.
  16. Maritz, B. & Alexander, G.J. 2014. Namaqua Dwarf Adders are generalist predators. African Journal of Herpetology 63: 79-86.
  17. Dalhuijsen, K., W.R. Branch & G.J. Alexander. 2014. Diet of Varanus albigularis and niloticus in South Africa. African Zoology 49: 83-93.
  18. Glaudis, X. and G.J. Alexander 2014. Bitis arietans (Puff Adder). Foraging Behavior. Herpetological Review 45: 139-140.
  19. Botts, E.A., B. F.N. Erasmus and G.J. Alexander. 2013. Small range size and narrow niche breadth predict range contractions in South African frogs. Global Ecology and Biogeography 22: 567-576.
  20. Maritz, B. & Alexander, G.J. 2013. Namaqua Dwarf Adders must breed frequently: the problem with being small. Journal of Zoology (London) 289: 27-31.
  21. Miller, A.K., B.F.N. Erasmus & G. J. Alexander. 2013. Gut and intestinal passage time in the Rainbow Skink (Trachylepis margaritifer): implications for stress measures using faecal analysis. Journal of Animal Physiology and Animal Nutrition. 97: 960-970.
  22. Alexander, G.J. 2012. Python natalensis (Smith, 1840). Southern African Python. Predation/diet. African Herp News 56: 25.
  23. Maritz, B. & Alexander, G.J. 2012. Movement Patterns in the Smallest Viper, Bitis schneideri. Copeia. 2012: 732-737.
  24. Alexander, G.J., A. Shirley Hanrahan & D. Mitchell. 2012. Assimilation Efficiency in an African Elapid Snake, Hemachatus haemachatus. African Journal of Herpetology. 61: 3-13.
  25. Botts, E.A., B. F.N. Erasmus & G.J. Alexander. 2012. Methods to detect species range size change from biological atlas data: a comparison using the South African Frog Atlas. Biological Conservation 146: 72-80.
  26. Maritz, B. & Alexander, G.J. 2012. Population density and survival estimates of the African viperid, Bitis schneideri. Herpetologica. 68: 195-202.
  27. Maritz, B., and G. J. Alexander. 2012. Dwarfs on the move: Spatial ecology of the world’s smallest viper, Bitis schneideri. Copeia 2012: 115-120.
  28. Maritz, B. and G.J. Alexander. 2011. Morphology, sexual dimorphism and growth in the smallest viperid, Bitis schneideri (Reptila: Squamata: Viperidae). Journal of Herpetology 45(4):457-462.
  29. Botts, E.A., B. F.N. Erasmus and G.J. Alexander. 2011. Geographic sampling bias in the South African Frog Atlas Project: implications for conservation planning. Biodiversity and Conservation 20: 119-139.
  30. Alexander, G.J. and C.J. Kruger. 2010. Bitis arietans arietans (Merrem, 1820). Winter mating activity. African Herp News 50: 30-33.
  31. Alexander, G.J. and B. Maitz. 2010. Bitis arietans arietans: Partial resistance to Naja venom African Herp News 50: 34-36.
  32. Maritz, B. and G.J. Alexander. 2010. Geogrpahical Distributions: Dendroaspis polylepis polylepis (Günther, 1864). African Herp News 51: 27-28.
  33. Warner, J.K. and G.J. Alexander. 2010. Bitis gabonica Gaboon Adder Diet and Prey Size. Herpetological Review. March
  34. McConnachie, S., G.J. Alexander and M.J. Whiting. 2009. Selected body temperature and thermoregulatory behavior in the sit-and-wait foraging lizard Pseudocordylus melanotus melanotus. Herpetological Monographs 23: 108-122.
  35. Maritz, B. and G.J. Alexander. 2009. Breaking Ground: Quantitative Fossorial Herpetofaunal Ecology in South Africa. African Journal of Herpetology 58: 1-15.
  36. Miller, A.K. and G.J. Alexander. 2009. Do dwarf chameleons (Bradypodion) show developmental plasticity? African Zoology 44: 45-54.
  37. Masterson, G.P.R., Maritz, B, Mackay, D and G.J. Alexander. 2009. The impacts of past cultivation on the reptiles in a South African grassland. African Journal of Herpetology 58: 71-84.
  38. Masterson, G.P.R., B. Maritz and G. J. Alexander. 2008. Effect of fire history and habitat structure on herpetofauna in a South African Grassland. Applied Herpetology 5: 129-143.
  39. McConnachie, S., G.J. Alexander and M.J. Whiting. 2007. Lower temperature tolerance in the temperate, ambush foraging lizard Pseudocordylus melanotus. Journal of thermal Biology 32: 66-71.
  40. Maritz, B., G.P.R. Masterson, D. Mackay and G.J. Alexander. 2007. Geographic distribution: Xenopus muelleri. Herpetological Review 38(2): 216.
  41. Maritz, B., G.P.R. Masterson, D. Mackay and G.J. Alexander. 2007. The effect of funnel trap type and size of pitfall trap on trap success: implications for ecological field studies. Amphibia-Reptilia 28: 321-328.
  42. Maritz, B. and G.J. Alexander. 2007. Herpetofaunal Utilisation of Riparian Buffer Zones in an Agricultural Landscape, in Mtunzini, South Africa. African Journal of Herpetology. 56: 163 - 169.


  1. Bates, M.F., Branch, W.R., Bauer, A.M., Burger, M., Marais, J., Alexander, G.J. and De Villiers, M.S. (eds). 2014. Atlas and Red List of the Reptiles of South Africa, Lesotho and Swaziland. Suricata 1. South African National Biodiversity Institute, Pretoria. p. 485.
  2. Alexander, G.J. and J. Marais 2007. A Guide to the Reptiles of Southern Africa. Struik. p. 408

Chapters in Books

  1. Alexander, G.J. 2015. Reptiles. Pp.64-67. In: Field Guide to Freshwater Life in Southern Africa. Eds Griffiths, C., Day, J. and M. Picker. Random House Struik.
  2. Collinson, W., Parker, D., Patterson-Abrolat, C., Alexander, G. & H. Davies-Mostert 2015, Chapter 54. Setjhaba SA, South Afrika: a South African perspective of an emerging transport infrastructure. Pp. 439-447. In Handbook of Road Ecology. Van der Ree, R., Grilo, R., and D. Smith (Eds). Wiley & Sons.
  3. Collinson, W., G.J. Alexander, H. Komen, & H. Davies-Mostert. 2012. Roadkill - a growing threat to biodiversity. Vision 19: 62-67.
  4. Alexander, G.J. 2011. Reptiles. Pp: 45-46. In Alien and Invasive Animals: A South African Perspective (eds. Picker, M. and C. Griffiths). Struik. Cape Town. 240 p.
  5. Alexander, G.J. 2007. Thermal Biology of the Southern African Python (Python natalensis): Does temperature limit distribution? Pp 50-75. In: Biology of the Boas and Pythons. R.W. Henderson and R. Powell. Eagle Mountain Publishing. LC.