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Tarleton State University (2015)

Ecological studies of squamate reptiles in northeastern Swaziland

Owen, Jacob Devlin

Titre : Ecological studies of squamate reptiles in northeastern Swaziland

Auteur : Owen, Jacob Devlin

Université de soutenance : Tarleton State University

Grade : Master of Science (MS) 2015

In Swaziland, a small African nation where much of the subtropical Lowveld region has been converted to sugarcane monoculture and the natural areas are understudied, we compared diversity and relative abundance of snake assemblages between protected areas and plantations as well as investigate diurnal saxicolous lizard assemblages in Mbuluzi Game Reserve. Using highways as a sampling transect, we encountered 20 of the 61 species of snakes reported from the country. Although species richness was similar between the two habitats, snakes were encountered over three times more frequently in protected areas than in sugarcane plantations. The threatened Southern African python, Python natalensis, was the most frequently encountered species along the transect, and was found exclusively in bushveld habitat. Although sample size was small, at the family level only elapids were more abundant in sugarcane. Our data indicate that overall, snake communities in northeastern Swaziland are adversely affected by intensive agriculture, but elapids may benefit from human-modified habitats. With the purpose of evaluating whether lizard species showed evidence of habitat or temporal partitioning, we found that three lizard species ( Platysaurus intermedius, Trachylepis margaritifera, and Trachylepis varia ) dominated rocky sites at Mbuluzi and we considered P. intermedius and P. margaritifera to be rock specialists, as these two species accounted for 91% of all lizard observations. We did not find evidence that these species partitioned qualitatively different categories of rock habitats (i.e., boulder, mixed boulder and rock face, rock face, and riverine rock), but these designations may be artificial. Both rock specialist species were more abundant in riverine rock habitat than in the other habitat categories. However, all three dominant species showed similar optimal ranges and peaks of activity with respect to ambient temperatures available over the course of the study and did not segregate activity according to sex. At our study site, diurnal saxicolous lizard species did not seem to partition habitat or time of activity. These results may simply reflect the scale of our observations as we did find that species richness was highest overall in the boulder category, the least rocky of our habitat categories, suggesting the possibility that rock specialists could exclude more generalist species from occupying sites with the most exposed rock. Also, the observation that both rock specialists increased in abundance in riverine rock habitat suggests that factors other than interspecific competition could limit populations, which may include absolute availability of resources or high predation rates.

Mots clés  : Ecology, Conservation, Biological sciences

Accès au document : Proquest Dissertations & Theses

Page publiée le 7 septembre 2015, mise à jour le 22 décembre 2017