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Title: A zone of geographic overlap between two morphologically similar African skinks
Authors: Stephens (SANBI), Kirstin
Telford (SANBI), Nicolas S.
Makhubo, Buyisile G.
Alexander, Graham J.
Tolley (SANBI), Krystal A.
Keywords: phylogenetics
South Africa
Trachylepis punctatissima
Trachylepis spilogaster
Issue Date: 9-Sep-2019
Abstract: Trachylepis is a morphologically conservative, species rich genus of African skinks. Recent genetic analyses within Trachylepis have identified several cryptic lineages as distinct species; however, phenotypic conservatism makes it difficult to rely only on morphology for distinguishing species, especially in the field. In the T. striata group, there are a number of species that are commonly misidentified in the field, for example T. punctatissima and T. spilogaster. Previous phylogenetic work reveals clear genetic divergence between the two species, yet their morphological similarity makes them difficult to distinguish particularly where they are in sympatry, such as in the North West Province, South Africa. Thus, the area of sympatry may either be genuine or the result of misidentification. We examined these alternatives by sequencing individuals from the potential overlap zone and evaluated them within a phylogenetic framework. A preliminary phylogeny using one mitochondrial marker (16S) was constructed using the Bayesian and maximum likelihood methods. There is evidence of a narrow zone of geographic overlap between the two species, although the area of sympatry appears to be smaller than previously thought. Given that the phylogeny showed a number of misidentified individuals in the presumed area of sympatry, the current species distributions are probably overestimated as a result of historical misidentifications. Furthermore, the phylogeny showed that misidentification is a common problem throughout the entire T. striata group with a number of other species being misidentified. For T. punctatissima and T. spilogaster, sympatry exacerbates the likelihood of misidentification and should be considered when the species is studied in the North West Province. Additionally, genetic identification should be used to confirm morphological identification when working on the T. striata group because many samples were found to be incorrectly identified.
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