Insect species richness tracking plant species richness in a diverse flora: gall-insects in the Cape Floristic Region, South Africa

The Cape Floristic Region (CFR) is one of the most plant-species-rich regions in the world. It is also a warm temperate region and hypothetically should have high gall-insect species richness, making it interesting to investigate the relationship between the insects of the region and the rich flora. The relationship between gall-insect species richness (GSR) and plant richness was investigated for the Fynbos and for representatives of vegetation of the whole CFR. Samples (of up to 600 plants per transect for Fynbos) of woody shrubs were investigated for the presence of galls. The species richness of these insects was quantified, as well as plant species richness for each transect. GSR for Fynbos was compared to global figures for GSR. Fynbos harboured significantly more gall-insect species than other CFR vegetation types. GSR was positively correlated with CFR plant richness. GSR also closely tracked plant richness in Fynbos. GSR was not significantly influenced by other variables (elevation and aspect), suggesting that plant richness per se was an important factor in generating GSR. Fynbos GSR is comparable to other sclerophyllous regions of high GSR globally, corroborating that this vegetation type is conducive to gall-insect diversification. There is likely to be a high percentage of gall-insect endemism in the Fynbos, as might be expected from the high host fidelity of this insect group. Received: 22 September 1997 / Accepted: 16 February 1998     

Impact of a dam on benthic macroinvertebrates in a small river in a biodiversity hotspot: Cape Floristic Region, South Africa

Suitable reservoirs and monitoring methods are needed to manage scarce water supplies in dry countries. We assessed here the impact on aquatic macroinvertebrates of the only dam on the Eerste River, which runs through the heart of a biodiversity hotspot, the Cape Floristic Region, South Africa. The dam and associated activities, were the only forms of disturbance in this otherwise pristine area. We sampled over 20,000 macroinvertebrate individuals and illustrated some categorical effects of the impoundment and its effects on macroinvertebrate assemblages. Macroinvertebrate species diversity below the dam was only half of that in the pristine catchment area above the dam. Furthermore, Ephemeroptera, Plecoptera and Trichoptera diversity and abundance dropped to almost zero as a result of the impoundment. In contrast, the abundance of the Diptera family Chironomidae increased substantially below the dam. These changes in macroinvertebrate diversity mirrored those recorded in biologically less diverse areas, but are of major concern in this biodiversity hotspot with its rich endemic fauna. We conclude that such an impoundment, while important for human welfare, results in a high price being paid in terms of loss of local biodiversity.     

Ground‐dwelling beetle assemblages in the northern Cape Floristic Region: Patterns,correlates and implications

Abstract Recent studies have both shown and predicted that global climate change will have a substantial influence on biodiversity. This is true especially of a global biodiversity hotspot, the Cape Floristic Region. Although the effects of predicted changes have been widely assessed for plants, little is known about how insect diversity in the region might be affected. In particular, patterns in and the correlates of diversity in the region are poorly understood, and therefore the likely affects of a changing abiotic environment on this significant group of organisms are not clear. Therefore, we investigate patterns in, and correlates of, epigaeic beetle (Tenebrionidae and Carabidae) diversity in one of the most climate change‐sensitive areas in the Cape Floristic Region, the Cederberg. In particular, we determine whether epigaeic beetle assemblage structure differs between the main vegetation types in the Cederberg (Strandveld, Mountain Fynbos and Succulent Karoo), how restricted these beetles are to specific vegetation types, and which environmental variables might be associated with site‐related differences in beetle richness and abundance. Sampling was undertaken during October 2002 and 2003 across an altitudinal gradient ranging from sea level (Lambert's Bay) to approximately 2000 m above sea level (Sneeukop, Cederberg) and down again to 500 m above sea level (Wupperthal) using pitfall traps. The environmental correlates of abundance and species density in the epigaeic beetles were similar to those identified previously for ants across the transect, with both taxa being positively related to several temperature variables. Several species showed habitat specificity and fidelity, and clear distinctions existed between the vegetation types across the transect. A larger proportion of the variance in tenebrionid species density was explained by environmental variables and spatial factors than for carabids. The most likely explanation for this difference is that the correlates might well reflect collinear historical processes, rather than a causal relationship between contemporary environmental variables and species density. If this is the case, it suggests that caution should be exercised when interpreting environmental correlates of species density, and making climate change predictions based on these correlates.     

A pragmatic approach to estimating the distributions and spatial requirements of the medium- to large-sized mammals in the Cape Floristic Region, South Africa

Conservation planning in the Cape Floristic Region, a recognized world plant diversity hotspot, required systematic information on the estimated distributions and spatial requirements of the medium- to large-sized mammals within each of 102 Broad Habitat Units delineated according to key biophysical parameters. As a consequence of a general lack of data, we derived a pragmatic approach for obtaining estimates of these two parameters. Distribution estimates were based on a combination of a literature survey (with emphasis on early texts) and the ecological requirements of the species. Spatial requirement estimates were derived from a simple spreadsheet model that is based on forage availability estimates and the metabolic requirements of the mammals in question. Our analysis incorporated adaptations of the agriculture-based Large Stock Unit or Animal Unit approach. The predictions of the model were tested by comparing them with actual density data. The outcomes provided realistic estimates of the two parameters. However, they should be considered as testable hypotheses and the concept of adaptive management — or management by hypothesis — must apply. Examples of the outcomes are provided in the form of maps and tables.     

Endemism and speciation in a lowland flora from the Gape Floristic Region

Taxonomic, edaphic and biological aspects of endemism were studied in a phanerogamous flora from the Agulhas Plain, a coastal lowland area of the Cape Floristic Region. Of the 1751 species in the flora, 23.6% were regional endemics and 5.7% were local endemics. Families which were over-represented in terms of endemics included the Ericaceae, Rutaceae, Proteaceae and Polygalaceae. Under-represented families included the Poaceae, Cyperaceae, Scrophulariaceae and Orchidaceae. Highest levels of local endemism were recorded on limestone and colluvial acid sand. Sixty-nine percent of regional endemics and 85% of local endemics were confined to a single substratum. An analysis of the frequency of biological traits associated with species with different categories of endemism enabled the establishment of a biological profile of a local endemic: a dwarf to low, non-sprouting shrub with soil stored seeds which are ant-dispersed and/or form a symbiotic relationship with microbes. It is argued that lineages with these characteristics are vulnerable to severe population reduction or even local extinction. An effect of this would be the promotion of rapid, edaphic speciation as a result of catastrophic selection. Thus, certain traits (e.g. non-sprouting) prevail or even predominate in the flora not because of any adaptive advantage but because high speciation rates of lineages which possess them, overwhelm low survival rates.     

Potential impact of viticulture expansion on habitat types in the Cape Floristic Region, South Africa

The wine industry in the Western Cape, South Africa has expanded over the past decade, particularly since the lifting of trade sanctions in 1992. Wine grapes are cultivated on fertile soils upon which threatened biodiversity habitat units of the Cape Floristic Region occur naturally. There is a concern as to whether further expansion of the wine industry, which would benefit the economy through increased foreign exchange, would encroach on the little remaining vegetation in vineyard-producing areas. Predictive land use modeling using logistic regression techniques was applied to determine suitable areas for vineyard cultivation according to climatic, topographic, and soil/geology variables. Of the most threatened habitats, 14849 hectares are particularly suitable for vineyards. Breede fynbos/renosterveld mosaic was the habitat most likely to be converted, and was considered 89.3% irreplaceable to current conservation goals. Also vulnerable are Ashton inland renosterveld and Boland coast renosterveld, the latter being 100% irreplaceable. Although the high rate in vine replanting suggests that the need for untransformed land will not be great immediately, an economic analysis showed that protection of these areas against future ploughing will be vital if targets of adequately representing each habitat in the Cape Floristic Region are to be met. Land use change modeling, especially if done in a spatially explicit and integrated manner with expert input, was shown to be an important technique for the extrapolation of historical patterns to understand the forces that shape landscapes, allowing for the assessment of management alternatives, and testing our understanding of key processes in land use changes that effect conservation planning.     

Potential impacts of future land use and climate change on the Red List status of the Proteaceae in the Cape Floristic Region, South Africa

Using spatial predictions of future threats to biodiversity, we assessed for the first time the relative potential impacts of future land use and climate change on the threat status of plant species. We thus estimated how many taxa could be affected by future threats that are usually not included in current IUCN Red List assessments. Here, we computed the Red List status including future threats of 227 Proteaceae taxa endemic to the Cape Floristic Region, South Africa, and compared this with their Red List status excluding future threats. We developed eight different land use and climate change scenarios for the year 2020, providing a range of best‐ to worst‐case scenarios. Four scenarios include only the effects of future land use change, while the other four also include the impacts of projected anthropogenic climate change (HadCM2 IS92a GGa), using niche‐based models. Up to a third of the 227 Proteaceae taxa are uplisted (become more threatened) by up to three threat categories if future threats as predicted for 2020 are included, and the proportion of threatened Proteaceae taxa rises on average by 9% (range 2–16%), depending on the scenario. With increasing severity of the scenarios, the proportion of Critically Endangered taxa increases from about 1% to 7% and almost 2% of the 227 Proteaceae taxa become Extinct because of climate change. Overall, climate change has the most severe effects on the Proteaceae, but land use change also severely affects some taxa. Most of the threatened taxa occur in low‐lying coastal areas, but the proportion of threatened taxa changes considerably in inland mountain areas if future threats are included. Our approach gives important insights into how, where and when future threats could affect species persistence and can in a sense be seen as a test of the value of planned interventions for conservation.     

High ploidy diversity and distinct patterns of cytotype distribution in a widespread species of Oxalis in the Greater Cape Floristic Region

Background and Aims

Genome duplication is widely acknowledged as a major force in the evolution of angiosperms, although the incidence of polyploidy in different floras may differ dramatically. The Greater Cape Floristic Region of southern Africa is one of the world''s biodiversity hotspots and is considered depauperate in polyploids. To test this assumption, ploidy variation was assessed in a widespread member of the largest geophytic genus in the Cape flora: Oxalis obtusa.

Methods

DNA flow cytometry complemented by confirmatory chromosome counts was used to determine ploidy levels in 355 populations of O. obtusa (1014 individuals) across its entire distribution range. Ecological differentiation among cytotypes was tested by comparing sets of vegetation and climatic variables extracted for each locality.

Key Results

Three majority (2x, 4x, 6x) and three minority (3x, 5x, 8x) cytotypes were detected in situ, in addition to a heptaploid individual originating from a botanical garden. While single-cytotype populations predominate, 12 mixed-ploidy populations were also found. The overall pattern of ploidy level distribution is quite complex, but some ecological segregation was observed. Hexaploids are the most common cytotype and prevail in the Fynbos biome. In contrast, tetraploids dominate in the Succulent Karoo biome. Precipitation parameters were identified as the most important climatic variables associated with cytotype distribution.

Conclusions

Although it would be premature to make generalizations regarding the role of genome duplication in the genesis of hyperdiversity of the Cape flora, the substantial and unexpected ploidy diversity in Oxalis obtusa is unparalleled in comparison with any other cytologically known native Cape plant species. The results suggest that ploidy variation in the Greater Cape Floristic Region may be much greater than currently assumed, which, given the documented role of polyploidy in speciation, has direct implications for radiation hypotheses in this biodiversity hotspot.     

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

One of the fundamental dimensions of biodiversity is the rate of species turnover across geographic distance. The Cape Floristic Region of South Africa has exceptionally high geographic species turnover, much of which is associated with groups of closely related species with mostly or completely non-overlapping distributions. A basic unresolved question about biodiversity in this global hotspot is the relative importance of ecological gradients in generating and maintaining high geographic turnover in the region. We used reciprocal transplant experiments to test the extent to which abiotic environmental factors may limit the distributions of a group of closely related species in the genus Protea (Proteaceae), and thus elevate species turnover in this diverse, iconic family. We tested whether these species have a “home site advantage” in demographic rates (germination, growth, mortality), and also parameterized stage-structured demographic models for the species. Two of the three native species were predicted to have a demographic advantage at their home sites. The models also predicted, however, that species could maintain positive population growth rates at sites beyond their current distribution limits. Thus the experiment suggests that abiotic limitation under current environmental conditions does not fully explain the observed distribution limits or resulting biogeographic pattern. One potentially important mechanism is dispersal limitation, which is consistent with estimates based on genetic data and mechanistic dispersal models, though other mechanisms including competition may also play a role. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Frequent and parallel habitat transitions as driver of unbounded radiations in the Cape flora

The enormous species richness in the Cape Floristic Region (CFR) of Southern Africa is the result of numerous radiations, but the temporal progression and possible mechanisms of these radiations are still poorly understood. Here, we explore the macroevolutionary dynamics of the Restionaceae, which include 340 species that are found in all vegetation types in the Cape flora and are ecologically dominant in fynbos. Using an almost complete (i.e., 98%) species‐level time calibrated phylogeny and models of diversification dynamics, we show that species diversification is constant through the Cenozoic, with no evidence of an acceleration with the onset of the modern winter‐wet climate, or a recent density‐dependent slowdown. Contrary to expectation, species inhabiting the oldest (montane) and most extensive (drylands) habitats did not undergo higher diversification rates than species in the younger (lowlands) and more restricted (wetland) habitats. We show that the rate of habitat transitions is more closely related to the speciation rate than to time, and that more than a quarter of all speciation events are associated with habitat transitions. This suggests that the unbounded Restionaceae diversification resulted from numerous, parallel, habitat shifts, rather than persistence in a habitat stimulating speciation. We speculate that this could be one of the mechanisms resulting in the hyperdiverse Cape flora.     

Water availability,fundamental niches and realized niches: A case study from the Cape flora

The ability of plants to survive drought or waterlogging constitutes an important niche parameter, which might be particularly significant in explaining species coexistence in the species‐rich and seasonally dry Cape Floristic Region of South Africa. However, the degree of physiological adaptation and specialization to these eco‐hydrological parameters (the fundamental niche) cannot be readily inferred from correlative studies based on species distributions and spatial variation in environmental parameters (the realized niche). We used an ex situ greenhouse experiment to compare the fundamental hydrological niches (different mean annual precipitation, rainfall seasonality and soil drainage) of six eco‐hydrologically divergent African Restionaceae species. Juvenile plants were subjected to six different watering treatments, ranging from no watering to waterlogging, to determine drought and waterlogging susceptibility and optimal growth conditions. We used the rate of biomass accumulation and survival rate as response measures. We found that species from dry and mesic (but well‐drained) habitats had optimal or near‐optimal growth at benign conditions (under which most restio species grow well). All species performed worse when droughted and died when not watered. Species from dry habitats tended to perform better (assessed in growth) than species from wet habitats under droughting. Species from wet habitats performed best when waterlogged, whereas species from dry habitats performed very poorly when waterlogged – thus showing that realized and fundamental niches covaried at the wet end of the hydrological gradient. We conclude that eco‐hydrological parameters are part of the fundamental niche, and fundamental and realized species niches are approximately correlated along them. The distribution of wet habitat species appears not to reflect their drought tolerance, suggesting that it may not be predicted by bioclimatic variables, but rather by soil drainage characteristics.     

Current and future threats to plant biodiversity on the Cape Peninsula, South Africa

The biodiversity of the Cape Peninsula (49127 ha in extent) has been considerably affected by various factors since European settlement in 1652. Urbanization and agriculture have transformed 37% of the original area of natural vegetation. Lowland vegetation types have been worst affected, with almost half of the transformation occurring in one of the 15 recognized vegetation types. Vegetation at high altitudes has been little affected by urbanization and agriculture, but alien trees and shrubs are now threatening biodiversity in these areas. Of the area not affected by urbanization and agriculture 10.7% is currently under dense stands (>25% canopy cover) of alien plants and another 32.9% is lightly invaded. Dense stands of Acacia cyclops, the most widespread invader, cover 2510 ha, 76% of the total area under dense alien stands. This paper assesses the impacts of these factors on aspects of the plant biodiversity of the area, namely, the distribution of major vegetation types and of endemic, rare and threatened plant taxa and of taxa in the Proteaceae (a prominent element in almost all communities, taken as an indicator of overall plant biodiversity).Possible future impacts on biodiversity are assessed by considering the effects of several scenarios involving increased urbanization and changes to alien plant control strategies and further spread over the next 50–100 years. The worst-case scenario for urbanization sees the area under natural vegelation reduced to 12163 ha (39.3% of its extent in 1994, or 24.8% of its original extent). Under this scenario almost a quater of the 161 endemic, rare and threatened (special) taxa are confined totally to urban areas; 57.4% of the known localities of these taxa, and 40.1% of the remaining localities of Proteaceae taxa are transformed. Dense alien stands currently affect 29.8% of the localities of special taxa known from herbarium records and 8.4% of these taxa currently occur only in areas at present affected by aliens. Clearing all dense stands would result in 62.9% of special taxa having less than half of their known localities affected (49.1% at present). Under this scenario, 92% of Proteaceae taxa have more than 75% of their localities unaffected by aliens. If clearing is confined to specific areas (the Cape Peninsula Protected Natural Environment or all publicly-owned land) and the aliens spread further outside these areas, the area of natural vegetation remaining shrinks (to 82.4% of the current extent if control is confined to public land). The further losses in biodiversity associated with these scenarios are described. If control programmes collapse and all potentially invadable land is occupied by dense alien stands, only 407 ha of natural vegetation would remain (1.5% of the current extent).The probability of the various scenarios materializing is discussed. To minimize further losses in biodiversity it is essential that: (1) a major initiative is launched immediately to clear (firstly) the 10184 ha of lightly invaded vegetation and then the 3313 ha of densely invaded vegetation; (2) no urban development be permitted within the boundaries of the Cape Peninsula Protected Natural Environment; (3) a systematic programme of prescribed burning (linked to the alien control programme) is initiated; and (4) contingency measures are implemented to improve the status of seriously threatened taxa, habitats and vegetation types.     

Insect diversity in Cape fynbos and neighbouring South African vegetation

Aim  It has often been suggested that South Africa's Cape fynbos shrublands, although extremely rich in plant species, are poor in insects, thus representing a notable exception from the broad plant–insect diversity relationship. The aims of this study were to compare the diversity patterns of plant-inhabiting insects in fynbos and the vegetation of three neighbouring biomes (grassland, subtropical thicket, and Nama-karoo), and to test for a general relationship between plant diversity and insect diversity across these biomes.
Location  South-western to south-eastern South Africa.
Methods  We conducted seasonal plant surveys and sweep insect sampling in 10 × 10 m plots in the Baviaanskloof Conservation Area (Eastern Cape), where all four biomes occur. We also conducted once-only collections in the core area of each biome.
Results  Fynbos plots had insect diversity values similar to those of grassland and subtropical thicket (a dense, evergreen and spinescent shrubland with a high abundance of succulents and climbers), and significantly higher than Nama-karoo (an open, semiarid shrubland). A remarkably strong positive relationship was found between plant and insect species richness.
Main conclusions  Previous generalizations were based on a few insect groups (e.g. butterflies, under-represented in fynbos), but ignored published results on other groups (e.g. galling insects, which are in fact over-represented in this vegetation). We show that, overall, insect diversity in fynbos is comparable to that of neighbouring biomes. Fynbos vegetation does not represent a significant exception from the broad positive relationship between plant diversity and insect diversity.     

Conservation of invertebrate biodiversity on a mountain in a global biodiversity hotspot,Cape Floral Region

Mountains present particular challenges for biodiversity conservation. Table Mountain is a significant mountain in a global biodiversity hotspot, the Cape Floristic Region. It has outstanding angiosperm diversity and endemism. Yet, aerial and foliage invertebrates in the area have been poorly studied, despite their importance as pollinators and predators. These plant and invertebrate assemblages are under great pressure from human disturbance. Aerial and foliage invertebrates were sampled with a range of techniques. Sites were chosen to make comparisons between vegetation structure and type, elevation and aspect. In total, 216 species from 63 families and 14 orders were recorded. Vegetation structure (fynbos or forest) and elevation were the most important environmental variables for both aerial and foliage invertebrates. Peak time for aerial invertebrate abundance was spring and summer in the fynbos and spring in the forests, while the foliage invertebrates showed very little seasonal variation. There was no correlation between the diversity of aerial and foliage invertebrates. When these results were compared with others on epigaeic invertebrates, it became clear that epigaeic and aerial invertebrates are not correlated, while epigaeic and foliage invertebrates were only partially correlated, but not sufficiently so to consider one as a reliable estimator of the other. The management pointer from this study is that sites at all elevations are vital for the conservation of biodiversity on Table Mountain. Both the aerial and epigaeic/foliage invertebrate assemblages will need to be monitored separately to maintain the mountain’s conservation status.     

Taphonomic and paleoecological change in the large mammal sequence from Boomplaas Cave,western Cape,South Africa

Excavations conducted by H.J. Deacon in the 1970s at Boomplaas Cave (BPA) uncovered a stratified sequence of Middle Stone Age (MSA) and Later Stone Age (LSA) deposits spanning the last >65,000 years. This study provides the first comprehensive and integrated taphonomic and paleoecological analysis of the BPA large mammals, with a focus on its implications for understanding human adaptations and environmental changes in southern Africa's Cape Floristic Region (CFR), an area that features prominently in understanding modern human origins. Taphonomic data indicate a complex history of human, carnivore, and raptor accumulation of the large mammal assemblage. The anthropogenic signal is largely absent from the bottom of the sequence (>65,000 years ago), intermediate in MSA and LSA assemblages from ∼50,000 to 20,000 years ago, and strong in LSA deposits post-dating the Last Glacial Maximum (LGM). When viewed in the broader CFR context, the inferred occupation history of BPA is consistent with the hypothesis that both MSA and LSA human populations were concentrated on the submerged coastline from ∼60,000 to ∼20,000 years ago. Intensive occupation following the LGM parallels an apparent increase in regional population densities, which may have been driven in part by rising sea levels. The BPA ungulate assemblage is characterized by the rise and decline of a taxonomically diverse grazing community, which peaks during the LGM. These changes are not correlated with taphonomic shifts, meaning that they are likely driven by environmental factors, namely the expansion and contraction of grassland habitats. Changes in ungulate diversity indicate that effective precipitation was highest during the LGM, corresponding with an intensified winter rainfall system. This is consistent with recent arguments that the LGM in this region may not have been extremely harsh and arid.     

A densely sampled ITS phylogeny of the Cape flagship genus Erica L. suggests numerous shifts in floral macro-morphology

Erica L. is the largest of the ‘Cape’ clades that together comprise around half of the disproportionately high species richness of the Cape Floristic Region (CFR) of South Africa. Around 840 species of Erica are currently recognised, C.680 of which are found in the CFR, the rest distributed across the rest of Southern Africa, the highlands of Tropical Africa and Madagascar, and Europe. Erica is taxonomically well documented, but very little is known about species-level relationships. We present the first densely sampled phylogenetic analysis of Erica, using nuclear ribosomal DNA sequences (internal transcribed spacers; ITS) of c. 45% of the species from across the full geographic range of the genus, both Calluna and Daboecia (Ericeae; monotypic genera and putative sister groups of Erica), and further Ericoideae outgroups. Our results show both morphological and geographic coherence of some clades, but numerous shifts in floral macro-morphology as represented by variation in individual morphological characters and pollination syndromes. European Ericeae is a paraphyletic grade subtending a monophyletic African/Malagasy Erica. Given the limited resolution of this single gene tree, more data are needed for further conclusions. Clades are identified that will serve as an effective guide for targeted sampling from multiple linkage groups.     

Two new species of Asteraceae (tribe Anthemideae,subtribe Pentziinae) from the Cape Floristic Region of South Africa

Two new species of Asteraceae (tribe Anthemideae, subtribe Pentziinae) from the Cape Floristic Region of South Africa are described. Marasmodes schlechteri Magee & J.C.Manning, a local endemic from the lowlands between Piketberg and the Olifants River Mountains, is distinguished by its spreading leaves with axillary fascicles and relatively large, solitary capitula with obconical involucre borne on very short lateral shoots. Pentzia trifida Schltr. ex. Magee & J.C.Manning is a well-collected limestone fynbos endemic that is readily distinguished by the regularly trifid leaves, broadly cyathiform involucres with lanceolate to oblanceolate bracts, and the well developed pappus extending the entire length of the relatively short corolla tube.     

New species and combinations in the African Restionaceae

Eight new species of the African Restionaceae (Restionoideae) are described, viz.: Cannomois anfracta, Cannomois arenicola, Cannomois grandis, Nevillea vlokii, Thamnochortus kammanassiae, Willdenowia pilleata, Restio uniflorus and Restio mkambatiae. A key to the species of Cannomois is provided, as well as a table comparing the characters of the three species in Nevillea. For all new species, notes on the affinities of the species and their habitats are provided. Two new combinations, Cannomois primosii (Pillans) H.P. Linder and Cannomois robusta (Kunth) H.P. Linder, are made.     

Diversification rate shifts in the Cape Floristic Region: The right traits in the right place at the right time

Species diversity patterns are the product of diversification rate variation, but the factors influencing changes in diversification rates are poorly known. Radiation is thought to be the result of ecological opportunity: the right traits in the right environment at the right time. We test this in the Cape Floristic Region (CFR) of South Africa, in which pyrophytic heathland (fynbos) and non-pyrophytic Afromontane forest occur interdigitated. We infer transitions from forest to fynbos in three Cape clades (Penaeaceae, Phyliceae and Diosmeae) and test if they are associated with diversification rate shifts and the evolution of functional traits linked to fire, high insolation and seasonal drought. We estimate diversification rate shifts using maximum likelihood and use phylogenetic comparative methods to show that forest to fynbos shifts were associated with decreases in leaf area and specific leaf area and preceded or coincided with increases in diversification rates. Furthermore, we show that Penaeaceae, Phyliceae and Diosmeae species are typical members of their vegetation types in terms of their traits. The diversification rate shifts of Penaeaceae and Phyliceae are dated to the Miocene, when postulated aridification-driven changes in the CFR fire regimes may have triggered expansion of the fynbos at the cost of forest, providing an ecological opportunity for the diversification of fynbos lineages.