Browsing by Author "Daniels, Savel R."
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- ItemGenetic variation in the Critically Endangered velvet worm Opisthopatus roseus (Onychophora: Peripatopsidae)(Open Journal Systems, 2011-10) Daniels, Savel R.In the present study the genetic variation of the Critically Endangered velvet worm species Opisthopatus roseus is examined. This species is endemic to the Ngele mistbelt forest in the KwaZulu-Natal province of South Africa. In recent years the forest has been severely impacted by anthropogenic activities such as logging of indigenous trees, construction of a national highway, commercial timber plantations and introduction of alien plant species, resulting in habitat fragmentation and potential range contraction for the species. A total of 35 specimens were collected from five sample sites (logs) in the Ngele Forest and sequenced for a partial fragment of the cytochrome c oxidase subunit one (COI) locus. In addition, the sex ratio at each sample sites was determined. A highly skewed sex ratio was detected within sites and only three males were present among the 35 O. roseus specimens. The results reveal the presence of 11 haplotypes and moderate genetic differentiation between the five sampled sites. In addition, it is evident that samples from the same log represented a mixture of haplotypes and did not comprise a single maternal haplotype. The results further suggest that gene flow between individuals occurs in the interior of the forest. Conservation implications of the present study are briefly discussed.
- ItemGrowth form and population genetic structure of Azorella selago on sub-Antarctic Marion Island(Cambridge Journals, 2008) Mortimer, Elizabeth; McGeoch, Melodie A.; Daniels, Savel R.; Jansen van Vuuren, BettineSeven community complexes have been described across sub-Antarctic Marion Island, amongst these fellfield that comprise low plant cover dominated by Azorella selago Hook. f. Azorella is considered a keystone species since it forms nutrient rich environments for microarthropod communities and epiphytic plants. Two distinct growth forms typify Azorella, namely discrete cushions and continuous mats. Whether these continuous mats normally consist of a single large cushion individual, or whether several individual plants merge, interdigitating to form a continuous area, remains unclear. As such, it is important to obtain some measure of Azorella growth dynamics before embarking on phylogeographic studies. Previous genetic studies indicated that several of these microarthropod species are significantly substructured across Marion Island, but it remains unclear whether similar subdivisions characterize Azorella. We used chloroplast sequence data (trnH-psbA) and amplified fragment length polymorphism (AFLP) to investigate these questions. No sequence variation characterized the trnH-psbA region in Azorella across Marion Island. In contrast, the AFLP results indicated that an A. selago mat comprises multiple individuals. We argue that mats can be formed through at least two processes namely fragmentation, where parts of the cushion plant die off creating open areas for the establishment of different individuals and/or to a high density of interdigitating individuals merging to form the mat. Fragment data further indicated significant substructure for Azorella across Marion Island (FST=0.101, P=0.01) and we attribute this to past vicariance.
- ItemMolecular evidence for cryptic species in the common slug eating snake Duberria lutrix lutrix (Squamata, Lamprophiidae) from South Africa(Pensoft, 2019-04-15) Kulenkampff, Kyle; Van Zyl, Francois; Klaus, Sebastian; Daniels, Savel R.; Jadin, R.We examined the impact of climatic fluctuations on the phylogeographic structure of the common slug eating snake (Duberria lutrix lutrix) throughout its distribution in South Africa. The evolutionary history within the taxon was examined using partial DNA sequence data for two mitochondrial genes (ND4 + cyt b) in combination with a nuclear locus (SPTBN1). Phylogenetic relationships were investigated for both the combined mtDNA and total evidence DNA sequence data. In addition, population and demographic analyses together with divergence time estimations were conducted on the combined mtDNA data. Topologies derived from the combined mtDNA analyses and the total evidence analyses were congruent and retrieved five statistically well-supported clades, suggesting that Duberria l. lutrix represents a species complex. The five clades were generally allopatric, separated by altitudinal barriers and characterised by the absence of shared mtDNA haplotypes suggesting long term isolation. Divergence time estimations indicate that the diversification within the D. l. lutrix species complex occurred during the Plio/Pleistocene as a result of climatic fluctuations and habitat shifts for the species. A taxonomic revision of the D. l. lutrix species complex may be required to delineate possible species boundaries.
- ItemA new species of Potamonautes from Sao Tome Island, Central Africa, with redescriptions of P. margaritarius (A. Milne-Edwards, 1869) from Sao Tome, and P. principe Cumberlidge, Clark and Baillie, 2002, from Principe (Decapoda: Potamonautidae)(Brill, 2018) Cumberlidge, Neil; Daniels, Savel R.Surveys of the freshwater crabs of two islands in the Gulf of Guinea, Central Africa, allowed a revision of the taxonomy of two little-known island endemic species, based for the first time on adult males: Potamonautes margaritarius (A. Milne-Edwards, 1869) from São Tomé, and of P. principe Cumberlidge, Clark and Baillie, 2002, from Príncipe (Brachyura; Potamonautidae). A new species of Potamonautes from southern São Tomé (Potamonautes saotome sp. nov.) is also described that is genetically distinct and has a clearly separate geographic distribution from P. margaritarius from northern São Tomé. The new species from southern São Tomé can be recognized by a suite of characters of the carapace, thoracic sternum, and gonopods. The taxonomy of P. margaritarius (A. Milne-Edwards, 1869) is stabilized by selecting a neotype from northern São Tomé. Potamonautes principe from Príncipe is the most distinct of the three taxa, with a more swollen carapace that has smooth anterolateral margins, and a shorter, straighter male first gonopod. All three taxa are morphologically distinct species that have also been clearly distinguished as evolutionarily separate lineages by mtDNA analysis and haplotyping in an earlier study. Previous phylogenetic evidence supports two separate island colonization events at different times in the past from different ancestral populations, one to São Tomé and another to Príncipe that resulted in the establishment of the endemic freshwater crab faunas of these two islands.
- ItemA new species of trogloplacine crab of the genus Australocarcinus Davie, 1988 from a freshwater stream in Mahé, Seychelles (Crustacea, Brachyura, Chasmocarcinidae)(Pensoft, 2018-02-19) Ng, Peter K. L.; Daniels, Savel R.; De Grave, S.A new species of freshwater chasmocarcinid crab, Australocarcinus insperatus sp. n., is described from the Seychelles Islands in the Indian Ocean. This is the first record of the genus and the subfamily Trogloplacinae Guinot, 1986, from the Indian Ocean, with all other members previously recorded from Australia, New Britain, New Caledonia, and Palau in the Pacific Ocean. The disjunct distribution of Australocarcinus is unexpected considering all trogoplacines are believed to practice direct development, lacking free-swimming larval stages. The new species is morphologically most similar to A. riparius Davie, 1988, from Queensland, Australia, but can be distinguished from its three congeners on the basis of the structures of its carapace, ambulatory legs and male first gonopod.
- ItemPhylogeographic patterning among two codistributed shrimp species (Crustacea: Decapoda: Palaemonidae) reveals high levels of connectivity across biogeographic regions along the South African coast(Public Library of Science, 2017-03-10) Wood, Louisa E.; De Grave, Sammy; Daniels, Savel R.We compare the genetic structuring and demographic history of two sympatric caridean shrimp species with distinct life history traits, one amphidromous species Palaemon capensis and one marine/estuarine species Palaemon peringueyi, in the historical biogeographical context of South Africa. A total of 103 specimens of P. capensis collected from 12 localities and 217 specimens of P. peringueyi collected from 24 localities were sequenced for the mitochondrial cytochrome oxidase one (CO1) locus. Results from analyses of molecular variance (AMOVA), pairwise ΦST comparisons and haplotype networks demonstrate weak to moderate genetic differentiation in P. capensis and P. peringueyi respectively. P. peringueyi exhibits partial isolation between populations associated with distinct biogeographic regions, likely driven by the region’s oceanography. However, there is minimal evidence for the occurrence of discrete regional evolutionary lineages. This demonstrated lack of genetic differentiation is consistent with a marine, highly dispersive planktonic phase in both the amphidromous P. capensis and the marine/estuarine P. peringueyi. Bayesian skyline plots, mismatch expansions and time since expansion indicate that both species maintained stable populations during the Last Glacial Maximum (LGM), unlike other southern African aquatic species.
- ItemPhylogeographic patterning among two codistributed shrimp species (crustacea: decapoda: palaemonidae) reveals high levels of connectivity across biogeographic regions along the South African coast(Public Library of Science, 2017-03-10) Wood, Louisa E.; De Grave, Sammy; Daniels, Savel R.We compare the genetic structuring and demographic history of two sympatric caridean shrimp species with distinct life history traits, one amphidromous species Palaemon capensis and one marine/estuarine species Palaemon peringueyi, in the historical biogeographical context of South Africa. A total of 103 specimens of P. capensis collected from 12 localities and 217 specimens of P. peringueyi collected from 24 localities were sequenced for the mitochondrial cytochrome oxidase one (CO1) locus. Results from analyses of molecular variance (AMOVA), pairwise ΦST comparisons and haplotype networks demonstrate weak to moderate genetic differentiation in P. capensis and P. peringueyi respectively. P. peringueyi exhibits partial isolation between populations associated with distinct biogeographic regions, likely driven by the region’s oceanography. However, there is minimal evidence for the occurrence of discrete regional evolutionary lineages. This demonstrated lack of genetic differentiation is consistent with a marine, highly dispersive planktonic phase in both the amphidromous P. capensis and the marine/estuarine P. peringueyi. Bayesian skyline plots, mismatch expansions and time since expansion indicate that both species maintained stable populations during the Last Glacial Maximum (LGM), unlike other southern African aquatic species.