South-western Cape Research Articles

Intertidal shellfish as a source of protein and energy for the Middle Stone Age inhabitants of the southwestern Cape and northern KwaZulu-Natal, South Africa

Intertidal mussels, limpets and oysters have been utilized as food by the prehistoric inhabitants of South African coastal regions since at least the Last Interglacial (130 ka). There is, however, little current information on their macronutrient content and nutritional value. In this paper, I present new, quantitative information on the protein, fat and energy content of two limpet and one mussel species from the Atlantic west coast (Cymbula granatina, Scutellastra granularis and Choromytilus meridionalis) and one mussel, one oyster and one limpet species from the northern coast of KwaZulu-Natal (Perna perna, Saccostrea culcullata and Patella concolor). The results of nutrient analyses show that many of these shellfish contain relatively large amounts of protein, fat and energy. When discussed alongside patterns in the archaeological record, these findings have important implications for our understanding of coastal foraging during the Middle Stone Age. Nutritional information and archaeological evidence indicate that simple marine molluscs were a significant source of protein and, to a lesser extent, energy, for the prehistoric inhabitants of the Atlantic west coast. In contrast, despite the good macronutrient returns of some species, shellfish were not a significant source of protein or energy for the Middle Stone Age occupants of Sibudu Cave in KwaZulu-Natal.

Effects of land use change on streamflow and stream water quality of a coastal catchment

This study aimed to link land cover/use change to water quality in an important water supply coastal catchment. The approach followed a spatial and temporal analysis of historical catchment land use change to assess how changes influenced water quality and river flow in the Touws and Duiwe Rivers, southwestern Cape, South Africa. Each sub-catchment has unique characteristics which influence land use and water quality and the purpose was to analyse each one separately. Historical water quality and flow analysis were based on the records available (Duiwe River: 1998–2013; Touws River: 1980–2013) together with rainfall data. Records were analysed to detect trends over time, which were linked to changes in land use activities. Agriculture intensified rapidly in the Duiwe River catchment with most arable land cultivated by 1960 and water storage as farm dams escalating. Concentrations of nutrients and electrical conductivity were higher in the Duiwe River than in the more natural Touws River, and were positively correlated to river flows. Mean values for total nitrogen and electrical conductivity were 0.03 mg/L and 16.7 mg/L, respectively, in the Touws River and 0.25 mg/L and 127 mg/L, respectively, in the Duiwe River. Nutrient concentrations decreased in the Duiwe River after 2006 as fertilizer applications to pastures were reduced. The South African Target Water Quality Ranges were exceeded at times and in the Touws catchment this appears to have been due to extensive fires. For instance, sodium concentrations reached a maximum of 1 874.5 mg/L in 1996 compared to a usual average concentration of 20.8 mg/L where the guidelines are between 0 and100 mg/L. The link between land cover/use and water quality was demonstrated and when spatial heterogeneity of the catchments was altered by human or natural events, this was reflected in changes in the water quality. Keywords : land cover, spatial analysis, sub-catchment scale

Between Precarity and Paternalism: Farm Workers and Trade Unions in South Africa's Western Cape Province

<p>The labour market in rural areas of South Africa’s Western Cape province has undergone considerable changes over the last thirty years. New labour and tenure legislation protecting farm workers combined with trade liberalisation, the abolition of subsidies and in-migration from other areas of South Africa has significantly reshaped labour on commercial farms. There is an increasing divide between permanent farm workers and a growing pool of precariously employed workers who labour seasonally on farms and are frequently employed through labour brokers. These divisions came to a head in 2012 when workers, many of whom work seasonally on farms, launched a strike that was to last for six months. Trade unions have struggled to organise an increasingly fragmented rural labour market and at the same time negotiate the forms of paternalism that continue to exert a strong influence over rural labour relations. Based on interviews with trade union organisers, this article examines how they have responded to the twin challenges of labour broking and paternalism. The farm strikes highlight the need for a form of social movement unionism that goes beyond wage demands and tackles the multiple factors that influence poverty in rural areas.</p>

A new Desmodillus (Gerbillinae, Rodentia) species from the early Pliocene site of Langebaanweg (South-western Cape, South Africa)

A new Desmodillus (Gerbillinae, Rodentia) species from the early Pliocene site of Langebaanweg (South-western Cape, South Africa)

Implications of summer breeding frogs from Langebaanweg, South Africa: Regional climate evolution at 5.1 mya


 
 
 No direct palaeoclimatic proxies have been available to indicate the seasonality or amount of rainfall on the west coast of southern Africa during the Early Pliocene. The Benguela Upwelling System (BUS) is today one of the factors responsible for the present-day aridity on the west coast of southern Africa. The initiation of the BUS is frequently linked to the entrenchment of aridity and the establishment of the current winter rainfall pattern on the west coast; however, marine proxies are inconclusive regarding the effects of past fluctuations in the BUS and sea surface temperatures on the rainfall regime. Neither the fossil evidence nor the fact that plants using the C3 photosynthetic pathway predominate at this time, provide direct evidence of winter rainfall at Langebaanweg. We challenge certain assumptions which are commonly made in the literature regarding the timing of inception of a winter rainfall regime on the west coast and the onset of aridity in the Langebaan region, and provide new evidence as to seasonality of rainfall at Langebaanweg in the Early Pliocene. Herein, the identification of frog species from the genus Ptychadena from Langebaanweg provides new and compelling evidence for a summer rainfall regime, or of at least significant summer rainfall, at 5.1 mya in the southwestern Cape of South Africa.
 
 
 
 
 Significance: 
 
 
 
 Advances understanding of the evolution of the winter rainfall zone on the west coast of South Africa
 Assesses evidence for the inception of aridity and a winter rainfall regime on the west coast of South Africa
 Fossil Ptychadenidae from the Early Pliocene site of Langebaanweg provide evidence for a summer rainfall regime at 5.1 mya on the west coast of the southwestern Cape.
 
 
 

Ecological research and conservation management in the Cape Floristic Region between 1945 and 2015: History, current understanding and future challenges

In 1945, the Royal Society of South Africa published a wide-ranging report, prepared by a committee led by Dr C.L. Wicht, dealing with the preservation of the globally unique and highly diverse vegetation of the south-western Cape. The publication of the Wicht Committee’s report signalled the initiation of a research programme aimed at understanding, and ultimately protecting, the unique and diverse ecosystems of the Cape Floristic Region. This programme has continued for over 70 years, and it constitutes the longest history of concerted scientific endeavour aimed at the conservation of an entire region and its constituent biota. This monograph has been prepared to mark the 70th anniversary of the Wicht Committee report. It provides a detailed overview of the circumstances that led up to the Wicht Committee’s report, and the historical context within which it was written. It traces the development of new and substantial scientific understanding over the past 70 years, particularly with regard to catchment hydrology, fire ecology, invasive alien plant ecology, the harvesting of plant material and conservation planning. The Wicht Committee’s report also made recommendations about ecosystem management, particularly with regard to the use of fire and the control of invasive alien plants, as well as for the establishment of protected areas. Subsequently, a combination of changing conservation philosophies and scientific conservation planning led to the creation and expansion of a network of protected areas that now covers nearly 19% of the Cape Floristic Region. We also review aspects of climate change, most of which could not have been foreseen by the Wicht Committee. We conclude that those responsible for the conservation of these ecosystems will face many challenges in the 21st century. These will include finding ways for effectively managing invasive alien plants and fires, as foreseen by the Wicht Committee. While the protected area network has expanded beyond the modest targets proposed by the Wicht Committee, funding has not kept pace with this expansion, with consequences for the ability to effectively manage protected areas. The research environment has also shifted away from long-term research conducted by scientists embedded in management agencies, to short-term studies conducted largely by academic institutions. This has removed a significant benefit that was gained from the long-term partnership between research and management that characterised the modis operandus of the Department of Forestry. Growing levels of illegal resource use and a changing global climate also pose new challenges that were not foreseen by the Wicht Committee.

Sources, transport and deposition of terrestrial organic material: A case study from southwestern Africa

Abstract Southwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific δ13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific δ13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific δ13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific δ13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent.

Children for Ewes: Child Indenture in the Post-Emancipation Great Karoo: c. 1856–1909

While the employment of child labour in the Cape Colony under slavery is well known, the same cannot be said for the post-emancipation period, despite the hinge masters and servants ordinance of 1841 governing the new free labour market legitimating employment of two categories of child labour: those indentured by their parents, and ‘destitute children’ indentured by the state. Both groups left paper trails. That of destitute children is easier to follow because they had to advertised in the press, but a few scattered sets of contracts of ‘indenture of apprenticeship by parents’ (IAP) survive in the archives of the colonial magistrates. The article offers a close reading of the destitute children advertisements and IAP contract archive for one such magistracy: that of Colesberg in the Great Karoo in the second half of the 19th century. It traces patterns in the aggregate demography, form and features of the more than 250 IAP contracts signed in the magistracy over this period to demonstrate the gendered nature of child indenture, its relation to and dampening effect on adult wage rates, and its contributions to reproducing proletarian households in the commercialising pastoral economy of the Great Karoo. In so doing, it troubles two prevailing assumptions about the post-emancipation Cape labour market: that settler employers dictated the terms of exchange through coercion, and that the proletarian household was a haven from such exploitation. It detects evidence for both the patrimonial exchange and parental exploitation of proletarian children. Finally, the article offers a corrective to the scholarship on the invention of colonial childhood in the final quarter of the 19th century, based exclusively on the white middle-class experience of the south-western Cape, by suggesting that post-emancipation black childhood was without formal education or indolent adolescence, but rather an apprenticeship in labour.

Marine and terrestrial foods as a source of brain-selective nutrients for early modern humans in the southwestern Cape, South Africa

Many attempts have been made to define and reconstruct the most plausible ecological and dietary niche of the earliest members of the human species. While earlier models emphasise big-game hunting in terrestrial, largely savannah environments, more recent scenarios consider the role of marine and aquatic foods as a source of polyunsaturated fatty acids (PUFA) and other brain-selective nutrients. Along the coast of southern Africa, there appears to be an association between the emergence of anatomically modern humans and accumulation of some of the earliest shell middens during the Middle Stone Age (200–40 ka). Fragmentary fossil remains classified as those of anatomically modern humans, along with marine food residues and numerous material cultural indicators of increased social and behavioural complexity have been recovered from coastal sites.In this paper, new information on the nutrient content of marine and terrestrial foods available to early modern humans in the southwestern Cape is presented and compared with existing data on the nutritional value of some wild plant and animal foods in Africa. The results suggest that coastal foraging, particularly the collection of abundant and predictable marine molluscs, would have allowed early modern humans to exploit some of the richest and most accessible sources of protein, micronutrients and longer-chain omega-6 and omega-3 fatty acids. Reliable and accessible sources of omega-3 eicosapentaenoic and docosahexaenoic acid are considerably more restricted in terrestrial foods.

A late Miocene–early Pliocene baleen whale assemblage from Langebaanweg, west coast of South Africa (Mammalia, Cetacea, Mysticeti)

Govender, R., Bisconti, M. & Chinsamy, A., June 2016. A late Miocene–early Pliocene baleen whale assemblage from Langebaanweg, west coast of South Africa (Mammalia, Cetacea, Mysticeti). Alcheringa 40, xxx–xxx. ISSN 0311-5518 Knowledge of post-Eocene cetaceans from Africa is very poor with almost nothing known about this group from southern Africa except for the diverse trawled ziphiids. Langebaanweg, a locality yielding prolific Miocene–Pliocene fossils on the southwestern Cape coast of South Africa, preserves terrestrial and marine biotas in juxtaposition. Palaeoenvironments vary from a marine shoreline to a lagoon and estuary and later a shallow marine environment and include several microhabitats. Fragmentary preservation of the cetacean skeletons suggests that they were transported before burial. This first detailed analysis of the Mio-Pliocene mysticete fossils from Langebaanweg uses the petrotympanic region to taxonomically identify specimens. Three un-named species of balaenopterid Mysticeti represent a Plesiobalaenoptera-like form, but it is premature to erect a new taxon based on this fragmentary material. The remaining material is too poorly preserved to be identified with confidence. Romala Govender [ rgovender@iziko.org.za ], Natural History Department, Iziko Museums of South Africa, PO Box 61, Cape Town, 8001, South Africa; Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift, 7701, Cape Town, South Africa, Michelangelo Bisconti [ michelangelobisconti@gmail.com ], Natural History Museum of San Diego, California, 1788 El Prado, San Diego, CA 92101, USA; Anusuya Chinsamy [ anusuya.chinsamy-turan@uct.ac.za ], Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift, 7701, Cape Town, South Africa.

<p><strong>Centres of moss diversity in southern Africa</strong></p>

Moss diversity in southern Africa is greatest in the Cape Fold Mountains of the southwestern Cape, and the Drakensberg mountains along the Great Escarpment of KwaZulu-Natal, Mpumalanga and Limpopo Provinces of South Africa. Five main, and five secondary centres of moss diversity are described, based on the number of moss species per half degree grid square in southern Africa (South Africa, Namibia, Botswana, Lesotho and Swaziland). The main centres are the Southwestern Cape, Outeniqua, Amathole, KwaZulu-Natal and Mpumalanga Centres of Moss Diversity. The KwaZulu-Natal centre is divided into the Drakensberg and Midlands Subcentres of Moss Diversity and the Mpumalanga centre into the Wolkberg and Blyde Subcentres of Moss Diversity. The secondary centres are the Cederberg, Witteberge, Pondoland, Magaliesberg and Soutpansberg Centres of Moss Diversity. Although collecting bias is responsible for concentrations of species records in many areas, moss diversity is strongly influenced by habitat heterogeneity and mean annual rainfall. This is in agreement with existing hypotheses of a broad-scale correlation between environmental heterogeneity and climate on the one side, and vascular plant diversity and distributions on the other.

A High Road to Sustainability? Wildflower Harvesting, Ethical Trade and Social Upgrading in South Africa's Western Cape

This paper evaluates the outcomes from an ambitious wildflower harvesting programme in South Africa's Western Cape, which has sought to achieve positive outcomes in terms of socio‐economic development and biodiversity conservation. Indigenous wildflowers, harvested according to conservation principles, are processed into ‘Cape Flora’ bouquets and sold into international and domestic markets. The principal supply chain provides an example of ethical trade due to the explicit environmental and social standards that are required at local sites of production. The incorporation of such standards represents an attempt to engender economic and social upgrading within the value chain. In this sense, the programme is consistent with dominant policy discourses, which suggest that exploiting potentially profitable niches within international trade flows represents a ‘high road’ to economic growth and transformation. The paper focuses upon the job creation and social impacts of the programme in the context of efforts to overcome South Africa's deeply entrenched socio‐economic disparities and high poverty levels. Despite impressive growth in production and exports during the global financial crisis, there have been mixed outcomes in terms of benefits to stakeholders at the upstream end of the supply chain. The paper concludes by considering the extent to which local initiatives operating under the framework of ethical trade possess the potential to facilitate effective social and economic upgrading.

Field relations, age, and tectonic setting of metamorphic and plutonic rocks in the Creignish Hills – North Mountain area, southwestern Cape Breton Island, Nova Scotia, Canada

The Creignish Hills and North Mountain areas of southwestern Cape Breton Island consist mostly of Neoproterozoic rocks typical of the Ganderian Bras d’Or terrane. U-Pb ages presented here for detrital zircon in the Blues Brook Formation of the Creignish Hills confirm a depositional age no greater than about 600 Ma. Although it is possible that some components of the formation are much older, similarities in rock types and field relations suggest that this is not the case. It is likely that the equivalent Malagawatch Formation of the North Mountain area, as well as high-grade metasedimentary rocks of the Melford Formation and Chuggin Road complex in the Creignish Hills and Lime Hill gneiss complex in the North Mountain area, represent the same or stratigraphically equivalent units as the Blues Brook Formation. The minimum ages of all of these units are constrained by cross-cutting syn- and post-tectonic plutons with ages mostly between 565 and 550 Ma, indicating that sediments were deposited, regionally metamorphosed, deformed, and intruded by plutons in less than 40–50 million years. The assemblage of pelitic, psammitic, and carbonate rocks indicates that a passive margin in a tropical climate was quickly changed to an active Andean-type continental margin in which voluminous calcalkaline dioritic to granitic plutons were emplaced. This sedimentary and tectonic history is characteristic of the Bras d’Or terrane and is shared by its likely correlative, the Brookville terrane in southern New Brunswick.

Indicative hazard profile for strong winds in South Africa

While various extreme wind studies have been undertaken for South Africa for the purpose of, amongst others, developing strong wind statistics, disaster models for the built environment and estimations of tornado risk, a general analysis of the strong wind hazard in South Africa according to the requirements of the National Disaster Management Centre is needed. The purpose of the research was to develop a national profile of the wind hazard in the country for eventual input into a national indicative risk and vulnerability profile. An analysis was undertaken with data from the South African Weather Service’s long-term weather stations to quantify the wind hazard on a municipal scale, taking into account that there are more than 220 municipalities in South Africa. South Africa is influenced by various strong wind mechanisms occurring at various spatial and temporal scales. This influence is reflected in the results of the analyses which indicated that the wind hazard across South Africa is highly variable, spatially and seasonally. A general result was that the strong wind hazard is highest from the southwestern Cape towards the central and eastern parts of the Northern Cape Province, and the southeastern parts of the coast as well as the eastern interior of the Eastern Cape Province. On a seasonal basis, the southern parts of the country showed similar magnitudes of relative wind hazard throughout the year. However, further north, a strong seasonal component was evident, with lowest risk of strong winds during autumn and winter, and highest risk in spring and summer when convective activity is strongest.

Evidence for aeolian origins of heuweltjies from buried gravel layers

Although heuweltjies (19–32 m diameter) dominate the surface of much of the southwestern Cape of South Africa, their origins, distribution and age remain controversial. Current hypotheses are that the heuweltjies are (1) constructed by the excavation and mounding habits of burrowing animals; (2) the result of erosion by water of areas between patches protected from fluvial action by denser vegetation or (3) the product of localised aeolian sediment accumulation beneath denser vegetation associated with termitaria. At a site where quartz-containing gravels occur on the soil surface in areas between heuweltjies, these gravels were found to extend as a relatively intact layer of uniform concentration from the inter-mound area into the mound at the same plane as the surrounding soil surface. This buried layer suggests that heuweltjies were either built-up by deposition on a previous soil surface layer or eroded from sediment accumulated above the buried gravel layer. Mounds contain a relatively large proportion of silt consistent with sediment deposition. Mound sediment elemental composition was strongly correlated with that of local shale, indicating a local source of sediment. Pedogenesis was considerably more advanced off- than on-mound. There was no evidence of extensive regional aeolian sediment mantling over the vast area in which the heuweltjies occur. These findings and observations support the aeolian deposition hypothesis of heuweltjie origins combined with a degree of erosion, rather than a termite bioturbation hypothesis or a predominantly erosion-based hypothesis.

Unequal contribution of native South African phylogeographic lineages to the invasion of the African clawed frog, Xenopus laevis, in Europe.

Due to both deliberate and accidental introductions, invasive African Clawed Frog (Xenopus laevis) populations have become established worldwide. In this study, we investigate the geographic origins of invasive X. laevis populations in France and Portugal using the phylogeographic structure of X. laevis in its native South African range. In total, 80 individuals from the whole area known to be invaded in France and Portugal were analysed for two mitochondrial and three nuclear genes, allowing a comparison with 185 specimens from the native range. Our results show that native phylogeographic lineages have contributed differently to invasive European X. laevis populations. In Portugal, genetic and historical data suggest a single colonization event involving a small number of individuals from the south-western Cape region in South Africa. In contrast, French invasive X. laevis encompass two distinct native phylogeographic lineages, i.e., one from the south-western Cape region and one from the northern regions of South Africa. The French X. laevis population is the first example of a X. laevis invasion involving multiple lineages. Moreover, the lack of population structure based on nuclear DNA suggests a potential role for admixture within the invasive French population.

Same-Sex Parented Families' Negotiation of Minority Social Identity in South Africa

ABSTRACTIn the past two decades, South Africa has made tremendous advancement in gay and lesbian rights. Despite this progress, many reports suggest that social attitudes have not kept up with legal progress, and gay and lesbian individuals in South Africa live in a society that is intolerant, oppressive, and even violent toward nonheterosexual citizens. The purpose of the current study was to explore same-sex parented families' interpretations of social attitudes toward gay/lesbian sexual orientation and the ways in which they negotiate their minority social identity status in their daily lives. Data were collected through in-depth interviews with 21 parents and 12 children in South Africa's Gauteng and Western Cape provinces. Despite many reports of social nonacceptance of gay/lesbian sexual orientation, participants largely reported positive perceptions of South African attitudes toward gay/lesbian families. Importantly, as most participants were White and middle-class, many acknowledged that non-White, non-middle-class sexual minorities likely do not share in these positive experiences. Participants reported negotiating social attitudes through ignoring, creating safe spaces, and altering behavior while in public. These strategies are discussed through the lens of social identity theory.

Genetic analyses of overfished silver kob Argyrosomus inodorus (Scieanidae) stocks along the southern African coast

Silver kob (Argyrosomus inodorus) is a sciaenid fish that has been targeted for more than 150 years by commercial and recreational fisheries in the coastal waters of Namibia and South Africa, where four main stocks have been hypothesised. In the present study, recently developed molecular markers were utilized to evaluate levels of genetic diversity and population structuring among such stocks. Moderate levels of genetic diversity and signatures of bottlenecking were found in the South African stocks (South Western Cape, Southern Cape and South Eastern Cape). Significant population genetic differentiation was detected between Namibia and South Africa, but not among the three putative South African stocks, indicating that the main oceanographic barrier for silver kob populations is to be found in the cool-temperate Benguela region, corroborating recent genetic studies. The lack of genetic structuring in South African waters indicates strong gene flow among the 3 South African putative stocks, which are characterized by distinct age and growth patterns. Thus, in order to guarantee a successful recovery of silver kob stocks, genetic findings should be used in conjunction with life-history and behavioral data to tailor future management measures aimed at mitigating the effects of different fisheries throughout the species’ distribution range.

Patterns of granivory in Acacia cyclops stands under biological control at Langebaanweg, South Africa

Low seed abundance associated with effect of biological control agents in an invasive shrub Acacia cyclops may limit its seed banks and further spread of the remaining seed crop in the South-western Cape, South Africa. However, there is a limited knowledge on how a reduced seed abundance, and vegetation cover which is positively correlated to seed bank size, affects patterns of granivory in A. cyclops stands. To fill this knowledge gap, granivory rates were measured using seed exclosure cages located both in closed and open A. cyclops tree canopy covers at Langebaanweg. Fresh seeds of A. cyclops were presented in tens per cage, and monitored in four-hour intervals of the day during the seeding season (December–July, 2013). Seed removal by rodents (74%) was not affected by vegetation cover suggesting an increased demand of the scarce seeds of A. cyclops. Conversely, seed removal by invertebrates (16%) was lowest among treatments, and was restricted in low tree canopy cover possibly due to competition for seeds under shady canopy. About 10% of the remaining seeds were consumed by vertebrates during the afternoon times associated with limited dispersal chances. In combination, biological control agents and rodents’ seed predation may effectively reduce seed banks of A. cyclops and invasion of this species in South Africa.

Biogeography and evolution of seeder and resprouter forms of Erica coccinea (Ericaceae) in the fire-prone Cape fynbos

The genus Erica represents the epitome of plant biodiversity in the South African Cape fynbos with over 700 species. This genus is composed of seeder and resprouter species, but both species diversity and endemism are strongly linked to the seeder habit and concentrated in the southwestern Cape Floristic Region (CFR). Erica coccinea is a relatively abundant and widespread fynbos species whose most remarkable morphological feature is the existence of distinct seeder and resprouter forms, frequently—but not always—in disjunct populations. Both higher within-population genetic diversity and among-population differentiation have been found in seeders, most likely as a consequence of the shorter generation times and faster population turnovers. Resprouters, despite being less diverse, are suspected to be ancestral. However, no solid evidence has yet been provided for the ancestrality of the resprouter form, or for the demographic processes that have determined the current distribution of genetic diversity in both regeneration forms. Here, we used microsatellites and sequences of the nuclear ribosomal internal transcribed spacers to describe the phylogeographic structure of seeder and resprouter E. c occinea populations and provide good evidence for the ancestral status of the resprouter form and the comparatively high rates of molecular evolution in derived seeder populations. We also reveal that mixed populations, where both seeder and resprouter individuals co-occur, were originated by secondary contacts. This study highlights the role of fire in driving accelerated diversification in seeder lineages of highly speciose CFR fynbos taxa.