LIVIVO - Search results -

Search results

Result 1 - 10 of total 10

Search options

Article ; Online: A Snap-Shot of Domatial Mite Diversity of Coffea arabica in Comparison to the Adjacent Umtamvuna Forest in South Africa

Sivuyisiwe Situngu / Nigel P. Barker / Susanne Vetter

Diversity, Vol 12, Iss 2, p

2020 Volume 79

Abstract: Some plant species possess structures known as leaf domatia, which house mites. The association between domatia-bearing plants and mites has been proposed to be mutualistic, and has been found to be important in species of economic value, such as grapes, ...

Abstract	Some plant species possess structures known as leaf domatia, which house mites. The association between domatia-bearing plants and mites has been proposed to be mutualistic, and has been found to be important in species of economic value, such as grapes, cotton, avocado and coffee. This is because leaf domatia affect the distribution, diversity and abundance of predatory and mycophagous mites found on the leaf surface. As a result, plants are thought to benefit from increased defence against pathogens and small arthropod herbivores. This study assesses the relative diversity and composition of mites on an economically important plant host ( Coffea aribica ) in comparison to mites found in a neighbouring indigenous forest in South Africa. Our results showed that the coffee plantations were associated with only predatory mites, some of which are indigenous to South Africa. This indicates that coffee plantations are able to be successfully colonised by indigenous beneficial mites. We also found an “edge effect”, in that coffee trees at the edge of the plantation hosted fewer mite species. These results are a snap-shot from a single sampling period. Nonetheless, they highlight the potential importance of this mutualism in commercial crop species and the possible role of faunal exchanges between indigenous and exotic crop species. This study expands our understanding of the mite−plant mutualism in Southern Africa, a region where acarological studies are sparse.
Keywords	leaf domatia–mite mutualism ; coffea arabica ; mite diversity ; edge effect ; south africa ; Biology (General) ; QH301-705.5
Subject code	580
Language	English
Publishing date	2020-02-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Habitat requirements affect genetic variation in three species of mayfly (Ephemeroptera, Baetidae) from South Africa

Chantal L. Taylor / Nigel P. Barker / Helen M. Barber-James / Martin H. Villet / Lyndall L. Pereira-da-Conceicoa

ZooKeys, Vol 936, Iss , Pp 1-

2020 Volume 24

Abstract: This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread (Afroptilum sudafricanum) and two stenotopic and thus endemic (Demoreptus natalensis and Demoreptus capensis) species, all of which co- ... ...

Abstract	This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread (Afroptilum sudafricanum) and two stenotopic and thus endemic (Demoreptus natalensis and Demoreptus capensis) species, all of which co-occur in the southern Great Escarpment, South Africa. Mitochondrial DNA was analysed to compare the genetic diversity between the habitat generalist and the two habitat specialists. Afroptilum sudafricanum showed no indication of population genetic structure due to geographic location, while both Demoreptus species revealed clear genetic differentiation between geographic localities and catchments, evident from phylogenetic analyses and high FST values from AMOVA. In addition, the phylogenetic analyses indicate some deeper haplotype divergences within A. sudafricanum and Demoreptus that merit taxonomic attention. These results give important insight into evolutionary processes occurring through habitat specialisation and population isolation. Further research and sampling across a wider geographic setting that includes both major mountain blocks of the Escarpment and lowland non-Escarpment sites will allow for refined understanding of biodiversity and associated habitat preferences, and illuminate comparative inferences into gene flow and cryptic speciation.
Keywords	Zoology ; QL1-991
Subject code	590 ; 580
Language	English
Publishing date	2020-05-01T00:00:00Z
Publisher	Pensoft Publishers
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Intraspecific mitochondrial gene variation can be as low as that of nuclear rRNA [version 2; peer review

Tshifhiwa G. Matumba / Jody Oliver / Nigel P. Barker / Christopher D. McQuaid / Peter R. Teske

F1000Research, Vol

2 approved]

2020 Volume 9

Abstract: Background: Mitochondrial DNA (mtDNA) has long been used to date historical demographic events. The idea that it is useful for molecular dating rests on the premise that its evolution is neutral. Even though this idea has long been challenged, the ... ...

Abstract	Background: Mitochondrial DNA (mtDNA) has long been used to date historical demographic events. The idea that it is useful for molecular dating rests on the premise that its evolution is neutral. Even though this idea has long been challenged, the evidence against clock-like evolution of mtDNA is often ignored. Here, we present a particularly clear and simple example to illustrate the implications of violations of the assumption of selective neutrality. Methods: DNA sequences were generated for the mtDNA COI gene and the nuclear 28S rRNA of two closely related rocky shore snails, and species-level variation was compared. Nuclear rRNA is not usually used to study intraspecific variation in species that are not spatially structured, presumably because this marker is assumed to evolve so slowly that it is more suitable for phylogenetics. Results: Even though high inter-specific divergence reflected the faster evolutionary rate of COI, intraspecific genetic variation was similar for both markers. As a result, estimates of population expansion times based on mismatch distributions differed between the two markers by millions of years. Conclusions: Assuming that 28S evolution is more clock-like, these findings can be explained by variation-reducing purifying selection in mtDNA at the species level, and an elevated divergence rate caused by diversifying selection between the two species. Although these two selective forces together make mtDNA suitable as a marker for species identifications by means of DNA barcoding because they create a ‘barcoding gap’, estimates of demographic change based on this marker can be expected to be highly unreliable. Our study contributes to the growing evidence that the utility of mtDNA sequence data beyond DNA barcoding is limited.
Keywords	Medicine ; R ; Science ; Q
Subject code	612
Language	English
Publishing date	2020-08-01T00:00:00Z
Publisher	F1000 Research Ltd
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: Genetic diversity of the endangered Faucaria tigrina (Aizoaceae) through ISSR âfingerprintingâ using automated fragment detection

Bentley, Luke / Anthony P. Dold / Nigel P. Barker

Biochemical systematics and ecology. 2015 Feb., v. 58

2015

Abstract: Faucaria tigrina (Haw.) Schwantes is a rare, threatened succulent found exclusively on the outskirts of Grahamstown, Eastern Cape, South Africa. There are three extant populations of the species; two large ones (approximately 300 and 620 adults) ... ...

Abstract	Faucaria tigrina (Haw.) Schwantes is a rare, threatened succulent found exclusively on the outskirts of Grahamstown, Eastern Cape, South Africa. There are three extant populations of the species; two large ones (approximately 300 and 620 adults) separated by under two kilometres, and a third very much smaller one slightly further away. Genetic theory expects that smaller, isolated populations face a loss in genetic variation through inbreeding and genetic drift and that as declining genetic variation is linked to a loss in fitness, this species may face extinction in the long term. This study used the ISSR-PCR genetic methods linked to an automated detection platform to determine if these populations are genetically distinct, and whether they are genetically depauperate. Two ISSR primers were used, and the automated detection system identified a total of 572 ISSR loci. An UPGMA clustering analysis showed each population to be genetically distinct, and that the genetic diversity of each population does not appear to be particularly low. F. tigrina is separable from the related Faucaria britteniae L. Bolus using the ISSR method, suggesting that this method may be appropriate for systematic studies in the Aizoaceae, which comprises many genera with closely related species.
Keywords	adults ; Aizoaceae ; cluster analysis ; extinction ; genetic drift ; genetic variation ; inbreeding ; loci ; microsatellite repeats ; South Africa
Language	English
Dates of publication	2015-02
Size	p. 156-161.
Publishing place	Elsevier Ltd
Document type	Article
ISSN	0305-1978
DOI	10.1016/j.bse.2014.11.012
Database	NAL-Catalogue (AGRICOLA)

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Scrutinising Multidimensional Challenges in the Maloti-Drakensberg (Lesotho/South Africa)

Jess L. Delves / V. Ralph Clark / Stefan Schneiderbauer / Nigel P. Barker / Jörg Szarzynski / Stefano Tondini / João de Deus Vidal / Andrea Membretti

Sustainability, Vol 13, Iss 8511, p

2021 Volume 8511

Abstract: The Maloti-Drakensberg (MD) is the largest and highest-elevation mountain system in southern Africa. Covering 40,000 km 2 and reaching 3500 m, the MD provides a range of ecosystem services (ES) to the entire southern African region—benefitting diverse ... ...

Abstract	The Maloti-Drakensberg (MD) is the largest and highest-elevation mountain system in southern Africa. Covering 40,000 km 2 and reaching 3500 m, the MD provides a range of ecosystem services (ES) to the entire southern African region—benefitting diverse users and extending well beyond the mountains. Rapid socioecological change threatens the provision of ES and presents multidimensional challenges to sustainable development. However, the continued land degradation and persisting socioeconomic problems indicate that development policy has not been effective in tackling these issues. In this paper, a multidisciplinary literature review forms the basis of a discussion which takes an ES framing to scrutinise the multidimensional social, political, economic and cultural issues in the study area. Three critical management systems are presented, and their associated ES are discussed, namely, water transfer, rangelands and conservation and tourism. In particular, the diversity of ES uses and values in the MD is considered. The results reveal the main drivers of continued unsustainable development and highlight important information gaps.
Keywords	traditional authorities ; governance systems ; land use ; Lesotho Highlands Water Project ; overgrazing ; Environmental effects of industries and plants ; TD194-195 ; Renewable energy sources ; TJ807-830 ; Environmental sciences ; GE1-350
Subject code	910
Language	English
Publishing date	2021-07-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: Evolution of foraging behaviour: Deep intra-generic genetic divergence between territorial and non-territorial southern African patellid limpets

Mmonwa, Kolobe L / Christopher D. McQuaid / Nigel P. Barker / Peter R. Teske

Molecular phylogenetics and evolution. 2017 Dec., v. 117

2017

Abstract: Southern Africa is a biodiversity hotspot of patellid limpets, with three genera (Helcion, Cymbula and Scutellastra) identified and described in the region. Scutellastra is the most diverse and most frequently studied of these and, along with Cymbula, ... ...

Abstract	Southern Africa is a biodiversity hotspot of patellid limpets, with three genera (Helcion, Cymbula and Scutellastra) identified and described in the region. Scutellastra is the most diverse and most frequently studied of these and, along with Cymbula, includes species with territorial and non-territorial foraging behaviours. We used three mitochondrial markers (12S rRNA, 16S rRNA and COI) and one nuclear marker (ATPSβ intron) to assess evolutionary relationships among species of Cymbula and Scutellastra with these two foraging behaviours and to identify which foraging mode is the more ancient. Maximum Likelihood and Bayesian Inference phylogenetic analyses revealed that the species sharing a foraging type are monophyletic in both genera. Territoriality is a derived character, as the clades with this foraging type are nested within a tree that otherwise comprises non-territorial taxa. These include Helcion, which was recovered as sister to the Cymbula/Scutellastra clade, and the next basal genus, Patella, which is ancestral to all southern African patellogastropods. Deep genetic divergence between the two foraging traits reflects strong adaptive effects of resource partitioning in the evolution of southern African patellid limpets.
Keywords	Bayesian theory ; biodiversity ; foraging ; genetic variation ; introns ; mitochondria ; monophyly ; Patellidae ; ribosomal RNA ; territoriality ; trees ; Southern Africa
Language	English
Dates of publication	2017-12
Size	p. 95-101.
Publishing place	Elsevier Inc.
Document type	Article
ZDB-ID	33610-5
ISSN	1095-9513 ; 1055-7903
ISSN (online)	1095-9513
ISSN	1055-7903
DOI	10.1016/j.ympev.2017.05.024
Database	NAL-Catalogue (AGRICOLA)

In stock of ZB MED Cologne/Königswinter

Zs.A 3644: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (2.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Molecular evidence of distinct evolutionary units in the sandhopper Talorchestia capensis (Amphipoda, Talitridae) along South African coasts

Baldanzi, Simone / Gavin Gouws / Nigel P. Barker / Sara Fratini

Hydrobiologia. 2016 Oct., v. 779, no. 1

2016

Abstract: Marine geographical and ecological barriers often reflect intraspecific genetic discontinuities among populations which may experience different selective pressures and undergo evolutionary divergence. While the phylogeography of marine intertidal ... ...

Abstract	Marine geographical and ecological barriers often reflect intraspecific genetic discontinuities among populations which may experience different selective pressures and undergo evolutionary divergence. While the phylogeography of marine intertidal invertebrates across the Atlantic/Indian Ocean transition received more attention, the population genetic structures of supralittoral direct developers across such transition area have been poorly investigated. Sandhoppers are supralittoral invertebrates characterised by a direct developmental mode (low dispersal ability), and Talorchestia capensis (Amphipoda, Talitridae) represents the most abundant species of sandhoppers along the South African coasts. To define population structure of T. capensis, we used a mitochondrial marker (the cytochrome oxidase subunit I gene, COX1). T. capensis showed a clean population structure with three main haplogroups genetically well separated, although this separation is not perfectly in line with geographical boundaries described for this area. The presence of separate evolutionary significant units is also confirmed by the shape of mismatch distribution, as well as the p distance values among groups. The overall results confirm the importance of mtDNA to retrieve information on the evolutionary history of species. This study suggests the evidence of a complex-species for this sandhoppers, which have never been considered before, providing fundamental basis for further studies.
Keywords	coasts ; cytochrome-c oxidase ; divergent evolution ; genes ; invertebrates ; littoral zone ; mitochondria ; mitochondrial DNA ; phylogeography ; population structure ; Talorchestia ; Indian Ocean
Language	English
Dates of publication	2016-10
Size	p. 35-46.
Publishing place	Springer International Publishing
Document type	Article
ZDB-ID	214428-1
ISSN	1573-5117 ; 0018-8158
ISSN (online)	1573-5117
ISSN	0018-8158
DOI	10.1007/s10750-016-2797-4
Database	NAL-Catalogue (AGRICOLA)

In stock of ZB MED Bonn / Germany

Z 73/704: Show issues
Einzelsign.: Show issues
4' 96/5026: Show issues

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: A review of marine phylogeography in southern Africa

Peter R. Teske / Sophie von der Heyden / Christopher D. McQuaid / Nigel P. Barker

South African Journal of Science, Vol 107, Iss 5/

2011 Volume 6

Abstract: The southern African marine realm is located at the transition zone between the Atlantic and Indo-Pacific biomes. Its biodiversity is particularly rich and comprises faunal and floral elements from the two major oceanic regions, as well as a large number ...

Abstract	The southern African marine realm is located at the transition zone between the Atlantic and Indo-Pacific biomes. Its biodiversity is particularly rich and comprises faunal and floral elements from the two major oceanic regions, as well as a large number of endemics. Within this realm, strikingly different biota occur in close geographic proximity to each other, and many of the species with distributions spanning two or more of the region’s marine biogeographic provinces are divided into evolutionary units that can often only be distinguished on the basis of genetic data. In this review, we describe the state of marine phylogeography in southern Africa, that is, the study of evolutionary relationships at the species level, or amongst closely related species, in relation to the region’s marine environment. We focus particularly on coastal phylogeography, where much progress has recently been made in identifying phylogeographic breaks and explaining how they originated and are maintained. We also highlight numerous shortcomings that should be addressed in the near future. These include: the limited data available for commercially important organisms, particularly offshore species; the paucity of oceanographic data for nearshore areas; a dearth of studies based on multilocus data; and the fact that studying the role of diversifying selection in speciation has been limited to physiological approaches to the exclusion of genetics. It is becoming apparent that the southern African marine realm is one of the world’s most interesting environments in which to study the evolutionary processes that shape not only regional, but also global patterns of marine biodiversity.
Keywords	phylogeographic break ; dispersal barrier ; asymmetrical gene flow ; marine vicariance ; cryptic speciation ; physiological adaptation ; Science ; Q ; Science (General) ; Q1-390 ; Social Sciences ; H ; Social sciences (General) ; H1-99
Subject code	333
Language	English
Publishing date	2011-05-01T00:00:00Z
Publisher	Academy of Science of South Africa
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Climate change, genetics or human choice

Peter R Teske / Isabelle Papadopoulos / Christopher D McQuaid / Brent K Newman / Nigel P Barker

PLoS ONE, Vol 2, Iss 7, p e

why were the shells of mankind's earliest ornament larger in the pleistocene than in the holocene?

2007 Volume 614

Abstract: BACKGROUND:The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from approximately 75,000 years ago (Pleistocene era) were found ... ...

Abstract	BACKGROUND:The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from approximately 75,000 years ago (Pleistocene era) were found in a cave located on South Africa's south coast. Beads made from N. kraussianus shells have also been found in deposits in this region dating from the beginning of the Holocene era (<10,000 years ago). These younger shells were significantly smaller, a phenomenon that has been attributed to a change in human preference. METHODOLOGY/PRINCIPAL FINDINGS:We investigated two alternative hypotheses explaining the difference in shell size: a) N. kraussianus comprises at least two genetic lineages that differ in size; b) the difference in shell size is due to phenotypic plasticity and is a function of environmental conditions. To test these hypotheses, we first reconstructed the species' phylogeographic history, and second, we measured the shell sizes of extant individuals throughout South Africa. Although two genetic lineages were identified, the sharing of haplotypes between these suggests that there is no genetic basis for the size differences. Extant individuals from the cool temperate west coast had significantly larger shells than populations in the remainder of the country, suggesting that N. kraussianus grows to a larger size in colder water. CONCLUSION/SIGNIFICANCE:The decrease in fossil shell size from Pleistocene to Holocene was likely due to increased temperatures as a result of climate change at the beginning of the present interglacial period. We hypothesise that the sizes of N. kraussianus fossil shells can therefore serve as indicators of the climatic conditions that were prevalent in a particular region at the time when they were deposited. Moreover, N. kraussianus could serve as a biomonitor to study the impacts of future climate change on coastal biota in southern Africa.
Keywords	Medicine ; R ; Science ; Q
Subject code	590
Language	English
Publishing date	2007-07-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: A review of marine phylogeography in southern Africa

Peter R. Teske / Sophie von der Heyden / Christopher D. McQuaid / Nigel P. Barker

Abstract	The southern African marine realm is located at the transition zone between the Atlantic and Indo-Pacific biomes. Its biodiversity is particularly rich and comprises faunal and floral elements from the two major oceanic regions, as well as a large number of endemics. Within this realm, strikingly different biota occur in close geographic proximity to each other, and many of the species with distributions spanning two or more of the region’s marine biogeographic provinces are divided into evolutionary units that can often only be distinguished on the basis of genetic data. In this review, we describe the state of marine phylogeography in southern Africa, that is, the study of evolutionary relationships at the species level, or amongst closely related species, in relation to the region’s marine environment. We focus particularly on coastal phylogeography, where much progress has recently been made in identifying phylogeographic breaks and explaining how they originated and are maintained. We also highlight numerous shortcomings that should be addressed in the near future. These include: the limited data available for commercially important organisms, particularly offshore species; the paucity of oceanographic data for nearshore areas; a dearth of studies based on multilocus data; and the fact that studying the role of diversifying selection in speciation has been limited to physiological approaches to the exclusion of genetics. It is becoming apparent that the southern African marine realm is one of the world’s most interesting environments in which to study the evolutionary processes that shape not only regional, but also global patterns of marine biodiversity.
Language	English
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾

To top

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Bonn / Germany

Order via subito

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

More links

Kategorien

Inter-library loan at ZB MED