2016-12-23T18:52:10

The high level of phenotypic diversity in southern African tent tortoises (Psammobates tentorius complex) has for decades prevented systematists from developing a stable taxonomy for the group. Here, we used a comprehensive DNA sequence dataset (mtDNA: Cytb, ND4, ND4 adjacent tRNA-His, and tRNA-Ser, 12S, 16S; and nDNA:PRLR gene) of 455 specimens, and the latest phylogenetic and species delimitation analytical procedures, to unravel the long-standing P. tentorius complex systematic puzzle. Our results for mtDNA and nDNA were incongruent, with the poorly supported nDNA phylogeny differentiating the three recognized subspecies, and showing potential hybridization in some regions. In contrast, the concatenated mtDNA phylogeny identified seven operational taxonomic units, with strong support. Clades 1, 4, 5, and 7 corresponded to tortoises identified as P. t. tentorius, clade 3 to P. t. trimeni, and clades 2 and 6 to P. t. verroxii. Our analyses showed conflicting topologies for the placement of C6 (P. t. verroxii north of the Orange River), with stronger support for it being sister to C2 + C3 than to the other clades. Clades 1, 2, and 6 had significantly higher genetic diversity than clades 3, 4, 5, and 7, perhaps because these clades inhabit substantially larger areas. The potential for future cladogenic radiations seems high in C1 and C6, particularly in C6 for which the within-clade diversification level was highest. Further research involving microsatellite DNA, phylogeographic evaluations, and morphological variation among clades is crucial for understanding the adaptive radiation of the P. tentorius complex and for modifying their taxonomy. K E Y W O R D SmtDNA, phylogeny, reptile, southern Africa, tent tortoise | 309 ZHAO et Al.

No abstract

Examination of evolutionary relationships in the Cape fossorial skink species complex (Acontinae: Acontias meleagris meleagris) reveals the presence of five cryptic lineages. -Zoologica Scripta, 38, 449-463. Variable morphological characters have obscured genealogical relationships in the Cape fossorial skink Acontias meleagris meleagris species complex. Currently the species complex contains four dubious operational taxonomic units (A. meleagris meleagris, A. m. orientalis, A. percivali tasmani and the morph lineicauda) with poorly defined species boundaries. In the present study we examine the evolutionary relationships within the species complex by sampling 24 skink populations from the known geographical distribution in the Western and Eastern Cape provinces of South Africa, representing a total of 119 specimens. We used partial sequence data derived from two mitochondrial DNA genes, 16S rRNA and COI, and one nuclear DNA gene, intron b-fibrinogen (b-fibint 7), to examine evolutionary relationships. Phylogenetic relationships were determined using both Maximum Parsimony (MP) and Bayesian inference (BI) from the combined mtDNA, nDNA and the total evidence data. Additionally we employed Maximum likelihood (ML) analyses on the total evidence data that comprised 1.5 kb. Topologies derived from the combined mtDNA analyses were congruent with the total evidence analyses (mtDNA + nDNA) and retrieved five major clades with strong statistical support inferred from bootstrapping and posterior probabilities. The five clades were genealogically and geographically exclusive, diagnostic at both the mtDNA and nDNA level and characterized by pronounced sequence divergence, with no shared haplotypes between clades. Collectively these results suggest the presence of five putative cryptic operational taxonomic units within the A. meleagris meleagris species complex. Constraining the traditionally recognized taxa always retrieved a statistically worse topology suggesting that considerable taxonomic revision is required. Our results indicate that traditional morphological characters need to be reassessed to define the five novel lineages in the A. meleagris meleagris species complex. The phylogeographic pattern for the fossorial skinks we retrieved was novel compared to phylogeographic studies for codistributed above ground living taxa. These results suggest that the abiotic and biotic factors that impact subterranean taxa may differ from supraterranean taxa.

Aim To determine the geographical boundaries among cryptic lineages and examine the evolutionary drivers of cladogenesis within the Cape legless skink, Acontias meleagris species complex.Location Coastal plains and adjacent interior of the Eastern, Northern and Western Cape provinces of South Africa.Methods A total of 231 specimens from 55 localities were collected from the entire known distribution range of the A. meleagris complex. Partial sequence data were collected from two mitochondrial DNA loci, 16S rRNA and cytochrome c oxidase subunit I (COI), and one protein-coding nuclear DNA locus, exophilin 5 (EXPH5). Phylogenetic, phylogeographical and population genetic analyses, together with divergence time estimation, were conducted on the DNA sequence data to examine evolutionary history and diversification within the species complex.Results Marked genetic structure was observed within the A. meleagris complex, and five clades were retrieved, most of which were statistically well supported. These five clades were also evident within the haplotypic analyses and were characterized by demographic stability. Cladogenesis was induced during the Pliocene/Pleistocene epochs, most likely as a result of oscillations in climate and sea level, and Neogene geomorphic phenomena. The Breede River Valley is an area of high genetic diversity and is likely to have served as a refugium.Main conclusions Lineage diversification and the current biogeographical patterning reflect the impact of sea level oscillations on historical coastal habitat availability. Fine-scale differences between co-distributed subterranean and supraterranean herpetofaunal taxa can be attributed to differences in life-history traits amongst different habitat types. Historical evolutionary drivers within this subterranean species complex are inferred and discussed.