"Nested" cryptic diversity in a widespread marine ecosystem engineer: a challenge for detecting biological invasions
- Authors: Teske, Peter R , Ruis, Marc , McQuaid, Christopher D , Styan, Craig A , Piggott, Maxine P , Benhissoune, Saïd , Fuentes-Grünewald, Claudio , Walls, Kathy , Page, Mike , Attard, Catherine R M , Cooke, Georgina M , McClusky, Claire F , Banks, Sam C , Barker, Nigel P , Beheregaray, Luciano B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445529 , vital:74396 , https://doi.org/10.1186/1471-2148-11-176
- Description: Ecosystem engineers facilitate habitat formation and enhance biodiversity, but when they become invasive, they present a critical threat to native communities because they can drastically alter the receiving habitat. Management of such species thus needs to be a priority, but the poorly resolved taxonomy of many ecosystem engineers represents a major obstacle to correctly identifying them as being either native or introduced. We address this dilemma by studying the sea squirt Pyura stolonifera, an important ecosystem engineer that dominates coastal communities particularly in the southern hemisphere. Using DNA sequence data from four independently evolving loci, we aimed to determine levels of cryptic diversity, the invasive or native status of each regional population, and the most appropriate sampling design for identifying the geographic ranges of each evolutionary unit.
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- Date Issued: 2011
A review of marine phylogeography in southern Africa
- Authors: Teske, Peter R , von der Heyden, Sophie , McQuaid, Christopher D , Barker, Nigel P
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445392 , vital:74382 , https://hdl.handle.net/10520/EJC97146
- Description: 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.
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- Date Issued: 2011
Associations in ephemeral systems: the lack of trophic relationships between sandhoppers and beach wrack
- Authors: Porri, Francesca , Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444552 , vital:74250 , https://doi.org/10.3354/meps08951
- Description: In ephemeral systems, material subsidies can play a key role in the persistence and connectivity of populations, especially if the organisms living within them are trophically dependent on imported resources. Sandy beaches are heavily subsidized by organic material of both terrestrial and marine origin. For highly mobile supratidal fringe species, such as amphipods, which are marine but with a high tolerance of aerial conditions, such material potentially provides both food and shelter. We investigated the relationship between beach wrack and amphipods by examining the trophic contribution of allochthonous food sources to sandhopper diets using stable isotope analysis. Replicate samples of the sandhopper Talorchestia capensis and several types of beach wrack (including seagrass, wood and different macrophytes) colonized by these amphipods were collected from 11 sites within one biogeographical region along the south coast of South Africa.
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- Date Issued: 2011
Climate‐driven genetic divergence of limpets with different life histories across a southeast African marine biogeographic disjunction: different processes, same outcome
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Mmonwa, Kolobe L , Matumba, Tshifhiwa G , McQuaid, Christopher D , Barker, Nigel P , Beheregaray, Luciano B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445420 , vital:74385 , https://doi.org/10.1111/j.1365-294X.2011.05307.x
- Description: Genetic divergence among populations of marine broadcast spawners in the absence of past geological barriers presents an intriguing challenge to understanding speciation in the sea. To determine how differences in life history affect genetic divergence and demographic histories across incomplete dispersal barriers, we conducted a comparative phylogeographic study of three intertidal limpets (Siphonaria spp.) represented on either side of a biogeographic disjunction separating tropical and subtropical marine provinces in southeastern Africa. Using a combination of mitochondrial and nuclear sequence data, we identified two distinct evolutionary lineages each in both Siphonaria concinna (a planktonic disperser) and S. nigerrima (a direct developer), and panmixia in a second planktonic disperser, S. capensis.
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- Date Issued: 2011
Geographic variation in the trophic ecology of an avian rocky shore predator, the African black oystercatcher, along the southern African coastline
- Authors: Kohler, Sophie A , Connan, Maëlle , Hill, Jaclyn M , Mablouké, Cécile , Bonnevie, Bo T , Ludynia, Katrin , Kemper, Jessica , Huisamen, Johan , Underhill, Leslie G , Cherel, Yves , McQuaid, Christopher D , Jaquemet, Sébastien
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444576 , vital:74252 , https://doi.org/10.3354/meps09215
- Description: The reflection of baseline isotopic signals along marine food chains up to higher trophic levels has been widely used in the study of oceanic top predators but rarely for intertidal predators. We investigated variation in the δ 13 C and δ 15 N ratios of a sedentary, rocky shore predator, the African black oystercatcher Haematopus moquini, over~ 2000 km of the southern African coastline, which is characterized by strong biogeographic patterns in primary productivity and intertidal communities. Blood and feathers from breeding adults and chicks and muscle tissues from primary prey items (mussels and limpets) were sampled between southern Namibia and the southeast coast of South Africa. 15 N enrichment was observed between the southeast and west coasts in oystercatcher tissues and their prey, mirroring an isotope shift between the oligotrophic Agulhas Current on the east coast and the eutrophic Benguela upwelling system on the west coast.
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- Date Issued: 2011
Stable isotope methods: the effect of gut contents on isotopic ratios of zooplankton
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444623 , vital:74255 , https://doi.org/10.1016/j.ecss.2011.02.002
- Description: In the past decade there has been an increased awareness of the potential for methodological bias resulting from multiple pre-analytical procedures in foodweb interpretations based on stable isotope techniques. In the case of small organisms, this includes the effect of gut contents on whole body signatures. Although gut contents may not reflect actual assimilation, their carbon and nitrogen values will be isotopically lighter than after the same material has been assimilated. The potential skewing of isotopic ratios in whole organism samples is especially important for aquatic environments as many studies involve trophic relationships among small zooplankton. This is particularly important in pelagic waters, where herbivorous zooplankton comprise small taxa. Hence this study investigated the effect of gut contents on the δ13C and δ15N ratios of three size classes of zooplankton (1.0–2.0, 2.0–4.0 and >4.0mm) collected using bongo net tows in the tropical waters of the south-west Indian Ocean. Animals were collected at night, when they were likely to be feeding, sieved into size classes and separated into genera. We focused on Euphausia spp which dominated zooplankton biomass. Three treatment types were processed: bulk animals, bulk animals without guts and tail muscle from each size class at 10 bongo stations.
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- Date Issued: 2011