Wednesday, January 31, 2018

[Herpetology • 2018] Systematics and Phylogeography of the Widely Distributed African Skink Trachylepis varia Species Complex: Trachylepis varia, T. damarana & T. laevigata



 Weinell & Bauer, 2018.

Highlights
• A molecular systematic study was conducted for the wide-ranging Trachylepis varia complex.
• Phylogenetic analyses support the existence of at least eight species within the Trachylepis varia complex.
• The Southern African members of the Trachylepis varia complex are phenotypically distinct.
• We update the taxonomy for the southern Africa members of the Trachylepis varia complex.
• Diversification within the Trachylepis varia complex began during the mid to late Miocene or early Pliocene.


Abstract
A systematic study of the Trachylepis varia complex was conducted using mitochondrial and nuclear DNA markers for individuals sampled across the species range. The taxonomic history of T. varia has been complicated and its broad geographic distribution and considerable phenotypic variation has made taxonomic revision difficult, leading earlier taxonomists to suggest that T. varia is a species complex. We used maximum likelihood and Bayesian inference to estimate gene trees and a multilocus time-tree, respectively, and we used these trees to identify the major clades (putative species) within T. varia. Additionally, we used morphological and color pattern data to distinguish and revise the taxonomy of the southern African clades. The major clades recovered in the multilocus time-tree were recovered in each of gene trees, although the relationships among these major clades differed across gene trees. Genetic data support the existence of at least eight species within the T. varia complex, each of which originated during the mid to late Miocene or early Pliocene. We focus our systematic discussion on the southern African members of the T. varia complex, revive Trachylepis damarana (Peters, 1870) and T. laevigata (Peters, 1869), and designate lectotypes for T. damarana and T. varia.

Keywords: Africa, Lygosominae, Phylogenetics, Phylogeography, Trachylepis damarana, Trachylepis laevigata




Trachylepis varia (Peters, 1867)
Euprepes varius Peters, 1867

Trachylepis laevigata (Peters, 1869)
Euprepes laevigatus Peters, 1869

Trachylepis damarana (Peters, 1870)
Euprepes damaranus Peters, 1870

  Trachylepis damarana from Haenertsberg, Limpopo Province, South Africa.


Conclusions: 
We find strong evidence that Trachylepis varia, T. damarana, and T. laevigata are distinct species that occur in southern Africa and that five additional, species-level clades occur north of the Zambezi and Kunene rivers, although future studies are needed to determine whether Trachylepis nyikae and Trachylepis isellii should also be recognized. The allopatric distribution and morphological distinctiveness of T. isellii (Largen and Spawls, 2010) suggests that this species is probably valid and the presence of multiple endemic species on the Nyika Plateau (Poynton, 1997; Burrows and Willis, 2005) suggests that T. nyikae may also be a valid species. Additionally, little is known about the distribution or natural history of the undescribed species sampled in Ethiopia, Democratic Republic of the Congo, or Tanzania. Lastly, next generation DNA sequencing may be useful in resolving deeper phylogenetic relationships within the T. varia complex and for distinguishing historical gene flow from incomplete lineage sorting. This study is the first to use genetic data to address species diversity, phylogenetic history, and taxonomic issues for the T. varia complex and is an example of how both genetic and phenotypic data can be used to resolve taxonomic problems and to estimate species ranges.


 Jeffrey L. Weinell and Aaron M. Bauer. 2018. Systematics and Phylogeography of the Widely Distributed African Skink Trachylepis varia Species Complex. Molecular Phylogenetics and Evolution.  120; 103-117. DOI: 10.1016/j.ympev.2017.11.014



No comments:

Post a Comment