Biology subjects

Teske, P. R.

Publications and source records attributed to Teske, P. R..

4 recordsLinked to original sources

bioRxiv2020

Limitations of DNA barcoding in determining the origin of smuggled seahorses and pipefishes

Seahorses and pipefishes are heavily exploited for use in Traditional Chinese Medicine (TCM), and less frequently for curio markets or as aquarium fish. A number of recent studies have used DNA barcoding to identify species sold at TCM markets in East Asia, but the usefulness of this approach in determining the region of origin remains poorly explored. Here, we generated DNA barcodes of dried seahorses and pipefishes destined for TCM that were confiscated at South Africas largest airport because they lacked the export permits required for the CITES-listed seahorses. These were compared with published sequences and new sequences generated for Mozambican seahorses, with the aim of determining whether it is possible to identify their country of origin. All pipefishes were identified as Syngnathoides biaculeatus, a widespread Indo-Pacific species, but the published sequence data did not provide sufficient resolution to identify the region of origin. The same was true of the majority of seahorses, which could not even be identified to species level because they clustered among an unresolved species complex whose sequences were published under the names Hippocampus kuda, H. fuscus and H. capensis. The presence of a few specimens of a second seahorse, H. camelopardalis, suggests that the shipment originated from East Africa because the range of this seahorse is centred around this region, but again, it was not possible to determine their country of origin. Even though seahorses and pipefishes have high levels of genetic population structure because of their low dispersal potential, DNA barcoding was only suitable to tentatively identify species, but not their region of origin. DNA barcoding is increasingly used to identify illegally traded wildlife, but our results show that more sophisticated methods are needed to monitor and police the trade in seahorses and pipefishes.

genetics↗

bioRxiv2020

Discovery of populations endemic to a marine biogeographical transition zone

AimBiogeographical transition zones are areas of overlap between the faunas of adjacent biogeographical entities. Particularly, the well-defined transition zones along linear coastlines are interesting natural laboratories to study dispersal and incipient speciation. Few studies have explored whether marine biogeographical transition zones harbour biodiversity that is distinct from that of the biogeographical entities they separate. The Wild Coast in eastern South Africa is a poorly-studied transition zone between regions warm-temperate and subtropical faunas, and is generally considered to be an area of faunal overlap. LocationThe South African portion of the Western Indian Ocean MethodsSequences of the DNA barcoding marker COI were generated from 306 estuarine sandprawns (Callichirus kraussi) collected at 13 sites. Genetic structure and evolutionary history were assessed using a haplotype network and a Bayesian discrete phylogeographic analysis. ResultTwo populations were identified whose ranges are centred on the Wild Coast, a rare one in the northern portion and a more common one in the central and southern portion of this biogeographical transition zone. These populations are not closely related to each other, but descend from subtropical and warm-temperate sister populations, respectively. ConclusionsThis is the first study to indicate that the Wild Coast marine biogeographical transition zone is not merely an area of faunal overlap, and one of very few studies to have discovered genetically unique populations within a marine biogeographical transition zone. The Wild Coast may harbour additional unique biodiversity that remains to be discovered, including rare species that require protection. More research is required to understand how this environmentally dynamic marine biogeographical transition zone differs from the adjacent biogeographical provinces.

ecology↗

bioRxiv2020

Mitogenome reconstruction of an endangered African seahorse from a Traditional Chinese Medicine market was based on a misidentification

The recently published complete mitochondrial genome of the endangered Knysna seahorse, Hippocampus capensis Boulenger, 1900, was based on a specimen obtained from a Traditional Chinese Medicine market. As H. capensis is endemic to temperate South Africa and exceptionally rare, illegal trade to supply Asian markets would constitute a considerable extinction risk. I investigated the phylogenetic placement of the Chinese specimen using mitochondrial DNA control region and cytochrome b sequences from the H. capensis mitogenome among corresponding published sequences of H. capensis and a number of closely related seahorse species. The Chinese specimen was distinct from H. capensis and instead clustered with H. casscsio, a seahorse that was recently described from the South China Sea. The sequences of H. casscsio clustered randomly among those of specimens identified as H. fuscus, a species whose taxonomic validity is disputed, and which is considered to be a synonym of the widespread Indo-Pacific seahorse H. kuda. Given that the morphological identification of seahorses is difficult, it is recommended that the publication of new species descriptions and genomic resources be preceded by a comprehensive comparison with the available molecular data. The taxonomy of seahorses is far from resolved, and cutting-edge molecular studies will not improve this situation if they do not take existing information into consideration.

evolutionary biology↗

bioRxiv2020

A globally threatened shark, Carcharias taurus, shows no population decline in South Africa

Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark Carcharias taurus (also known as the sandtiger or grey nurse shark) is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, it was found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. Taurus population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.

genetics↗