Capensis Research Articles

The phylogenetically isolated South African endemic diving beetle Caperhantus cicurius (Fabricius, 1787): redescription and range extensions (Coleoptera, Dytiscidae, Colymbetinae)

New distribution records and a redescription are presented for Caperhantus cicurius (Fabricius, 1787), a diving beetle endemic to the Cape region of South Africa, which is only distantly related to other Afrotropical dytiscids. We show that the species is much more widely distributed than previously recognized and present details of occupied habitats for the first time. Caperhantus cicurius occurs throughout the winter rainfall zone in South Africa, from Namaqualand to the Eastern Cape Province, particularly in temporary waters in the Fynbos and Succulent Karoo biomes.

Post-fire clumping of seedlings of Cape Proteaceae species: ecological, evolutionary and conservation implications

Background Spatial clumping of plants results in intense competition. Aims We analysed the extent of clumping of Proteaceae seedlings across the Cape Floristic Region after fire. Methods To demonstrate the extent of clumping in 23 species, we analysed the seedling and adult densities in 290 post-fire surveys each of 100 × 1 m2 plots using standard indices of clumping. Key results We detected clumping of Cape Proteaceae seedlings, whereas parent plants were less clumped. The clumping is not due to limited safe sites for seedlings because the number of plots at a site with at least one seedling was positively related to the number of seedlings at the site. Sites with seedlings were enriched in nutrients relative to those without. Conclusions The possible benefits of clumping are saturation of granivores and co-location of buried seeds with nutrient-rich patches of fire-derived ash and debris. A cause of clumping is seeds sticking together. Clumping, which is strongly intraspecific, has implications for trait evolution and the dominance of reseeders over resprouters. Strong clumping reduces the usefulness of the widely used seedling:parent index to determine whether fires were favourable or not. Implications Clumping has implications for understanding seed dispersal distances, seedling versus adult traits, fire responses and demography.

Skull morphology analysis suggests the extinct Cape lion, Panthera leo melanochaita (Smith, 1842), is not distinctive

The lion (Panthera leo) was extirpated from the Cape region of South Africa during the mid-nineteenth century. Whilst historically classified as a distinct subspecies known as the Cape lion (P. l. melanochaita), recent molecular studies challenge the distinctiveness of this population, suggesting that it represents the southernmost population of the species' Southern Clade. The Cape lion is often cited as having a distinctive skull morphology, which has justified its subspecific classification, but only a limited number of specimens have been available for examination, so that the Cape lion’s skull morphology has not been satisfactorily understood. In this study we collected morphometric data from a greatly enlarged sample of 22 Cape lion skulls, including 12 adults, constituting the largest sample size analysed for this possible subspecies. The results suggest that (1) morphological characteristics of the skull previously thought to distinguish the Cape lion are not diagnostic, and (2) nor is the skull morphology of male and female Cape lions distinct from that of males and females of other southern African lions. Our results independently support those based on molecular investigations, which suggest that the Cape lion was not distinct from other lions within the Southern Clade.

Geographic based phenolic compound variations in South African Schinus molle L. peppercorns

Environmental conditions affect polyphenolic compounds in plants, and yet little is known about the response of Schinus molle peppercorns to geographical location. S molle is a folkloric pseudospice of Andean origin possessing multiple culinary and medicinal functions. This globally invasive species presents an immense multidimensional potential. Polyphenolic compounds were therefore profiled and quantified from pink peppercorns growing in 12 distinct locations in the Eastern and Western Cape provinces of South Africa using UPLC-QTOF-MS techniques. Eleven flavonoids were reported, including epigallocatechin gallate, +)-tephrorin B, astilbin, procyanidin B5, 4-benzyl-7-hydroxy-3-phenyl-2H-chromen-2-one, and isochamaejasmin which were reported for the first time in this species. Five phenolic acids, three glycosides, and tannins (theogallin (3-galloylquinic acid), digalloyl quinic acid, digalloylshikimic acid, β-glucogallin A and β-glucogallin B) were also revealed among others. PCA revealed a high composition of polyphenolic compounds in the Eastern in comparison to the Western Cape regions. Flavonoids were glaringly higher in winter rainfall receiving coastal regions. Consequently, the highest catechin content was 229% higher in the Eastern (1269.9 mg/kg) than the Western Cape (553.4 mg/kg). Furthermore, isochamaejasmin, the compound with possibly the highest concentration is reported in George (1741 mg/kg) and Gqeberha (2601.2 mg/kg) representing 149% differences between the two regions. Soil type alone did not conclusively appear to influence polyphenolic compound accumulation in this study. Elucidating the distribution of polyphenolic compounds in this species could open new insights for potential therapeutic, pharmaceutical, and agricultural applications including possibilities for new and improved organic drugs, and food product development.

Evidence for moth pollination in a rhinomyiophilous Erica species from the Cape Floristic Region of South Africa.

Contrasting pollination syndromes in closely related species suggest that floral trait divergence is associated with differences in pollination system, but empirical observations are required to confirm syndrome-based predictions. We present a comparative study of two closely related Erica species with contrasting pollination syndromes from the Cape Floristic Region of South Africa. Ericacylindrica has narrowly tubular pale and strongly scented flowers and is known to be hawkmoth-pollinated. The closely related Ericainfundibuliformis has bright flower colours and appears to lack scent, traits that are suggestive of pollination by long-tongued nemestrinid flies (rhinomyiophily). Floral trait measurements revealed that both species exhibit predominantly upright flower orientation and elongated floral tubes, although tube length of E.infundibuliformis is consistently greater than that of E.cylindrica. For both species, petals are brighter than floral tube surfaces, but flowers of E.cylindrica lack the strong UV reflectance found in E.infundibuliformis. Nectar of E.infundibuliformis is more concentrated and produced in larger volumes. Scent composition, but not evening scent emission rates, differed between the species: scent of E.cylindrica is dominated by aromatic compounds, whereas scent of E.infundibuliformis is dominated by (E)-ocimene and other terpenoid compounds and is emitted at higher rates during the day than the evening. Pollinator observations contradicted trait-based predictions: although a single nemestrinid fly captured in the vicinity of E.infundibuliformis did carry Erica pollen, almost all other diurnal flower visitors were nectar-robbing Hymenoptera which did not carry Erica pollen. Contrary to predictions, at two sites and over two flowering seasons, flowers were consistently visited in the evenings by several species of settling moths and hawkmoths which carried pollen, almost exclusively of Erica, on their proboscides. Our findings thus suggest that, despite objective differences in key floral traits between the closely related hawkmoth-pollinated E.cylindrica and E.infundibuliformis, moths are also important pollinators of E.infundibuliformis. A bimodal pollination system involving predominant pollination by moths and occasional visits by long-proboscid flies could partially reconcile findings with predictions. Our study further suggests that hawkmoth pollination may be more widespread in both Erica and the broader Cape flora than has hitherto been assumed and emphasises the importance of nocturnal pollinator observations.

Pollinator shifts despite hybridisation in the Cape's hyperdiverse heathers (Erica, Ericaceae).

Interrogating the ecological and geographic factors that influence population divergence dynamics can reveal why some groups of organisms diversify more prolifically than others. One such group is the heathers (Erica, Ericaceae), the largest plant genus in the Cape Floristic Region. We study Erica abietina, a highly variable species complex with four subspecies differing in geographic range, habitat and pollination syndrome. We test for population differentiation, hybridisation, introgression and pollinator-driven divergence using genotyping-by-sequencing on samples across the entire distribution. We find five variably distinct genetic groups, with one subspecies comprising two independent lineages that are geographically isolated and occur on different soil types. Phylogenetic analysis suggests two independent shifts between bird and insect pollination, with accompanying genetic divergence. However, for one pair of populations with different pollinators, we uncover several individuals of hybrid origin at a site of sympatry. These results suggest that floral differentiation driven by divergent selection acts in concert with geographic isolation to maintain reproductive isolation and promote speciation. Our investigations reveal a highly dynamic system whose diversity has been shaped by a variety of interacting forces. We suggest that such a system could be a model for much of the diversification of the Cape flora.

Eco-evolutionary origins and diversification in a megadiverse hotspot: Arthropods in the Greater Cape Floristic Region.

The Greater Cape Floristic Region at the southern tip of Africa is a global megadiversity hotspot. The region's biodiversity has been driven by a long history of topographic, climatic, and sea level change coupled with geological uplift, and without being exposed to any major climate events such as glaciations since the breakup of Gondwana. Among arthropods, this long history has led to the survival of many ancient lineages, manifested by much disparity followed by considerable speciation in more recent times, with the emergence of many cryptic species flocks. There is much convergence among the various taxa and functional groups in how they have responded to the various environmental filters of the past. There has also been the development of a great many morphological, behavioral, and microhabitat specialisms, associated with both topography and particular habitats, as well as interactions with other organisms. Morphological and molecular advances are elucidating how this megadiversity came about. There are indications that among the arthropod fauna, especially species that are small-sized and have cryptic lifestyles, many more taxa remain to be discovered. Here, we review the eco-evolutionary trends that have occurred in this region and that have resulted in such remarkable arthropod diversity. Conservation of the arthropod fauna requires recognition of this historical biogeography and ecology. Instigation of approaches over wide areas is required so as to encompass all this diversity.

Exploring the wound healing potential of Lobostemon fruticosus using in vitro and in vivo bioassays

Ethnopharmacological relevanceLobostemon fruticosus (L.) H.Buek is a perennial and woody shrub of the Boraginaceae family, found in the Cape region of South Africa. The leaves and twigs are used to treat dermatological conditions such as wounds, burns, ringworm, erysipelas and eczema. Anti-inflammatory, antibacterial, antiviral and anti-proliferative activities of L. fruticosus have been reported. However, there is a void in research which reports on the wound healing properties of this plant. Aim of the studyAligned with the traditional use of L. fruticosus, our study aimed to use in vitro and in vivo bioassays to confirm the wound healing potential of the plant. Materials and methodsAn aqueous methanol extract (80% v/v) of L. fruticosus was prepared using a sample collected from the Western Cape Province of South Africa and chromatographically profiled by ultra-performance liquid chromatography coupled to mass spectrometry (UPLC-MS). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay was performed to determine the non-toxic concentrations of the extract for subsequent use in the in vitro scratch assay. Both the human keratinocyte (HaCaT) and fibroblast (BJ-5ta) cell lines were employed in the in vitro scratch assay. The in vivo caudal fin amputation assay was used to assess the wound healing potential of L. fruticosus, by monitoring fin regeneration in zebrafish larvae treated with the plant extract at various concentrations. ResultsSix major compounds were tentatively identified in the L. fruticosus extract namely; globoidnan A, globoidnan B, rutin, rabdosiin, sagerinic acid and rosmarinic acid. The potentially toxic pyrrolizidine alkaloids were also identified and quantitatively confirmed to be present at a low concentration of 119.58 ppm (m/m). Treatment of HaCaT and BJ-5ta cells with the plant extract in the scratch assay resulted in an increase in cell migration, which translates to accelerated wound closure. After 24 hr treatment with 100 μg/mL of extract, wound closure was recorded to be 91.1 ± 5.7% and 94.1 ± 1.3% for the HaCaT and BJ-5ta cells, respectively, while the untreated (medium) controls showed 72.3 ± 3.3% and 73.0 ± 4.3% for the two cell lines, respectively. Complete wound closure was observed between 24 and 36 hr, while the untreated control group did not achieve 100% wound closure by the end of the observation period (48 hr). In vivo, the crude extract at 100 μg/mL accelerated zebrafish caudal fin regeneration achieving 100.5 ± 3.8% regeneration compared to 68.3 ± 6.6% in the untreated control at two days post amputation. ConclusionsThe study affirms the wound healing properties, as well as low toxicity of L. fruticosus using both in vitro and in vivo assays, which supports the traditional medicinal use. Other in vitro assays that target different mechanisms involved in wound healing should be investigated to support the current findings.

Bivalves of superfamily Galeommatoidea (Mollusca, Bivalvia) from western South Africa, with observations on commensal relationships and habitats.

The Galeommatoidea are a diverse but little-studied group of small bivalves, well known for the symbiotic relationships many species have with a range of invertebrate taxa. Four species collected from the Western Cape region of South Africa were examined and illustrated, providing new details on their habitat preferences, and depicting the mantle structure of live specimens for the first time. Brachiomyaducentiunus sp. nov., is described herein, and an additional record of Montacutasubstriata (Montagu, 1808) is reported from South Africa. Brachiomyaducentiunus and Montacutasubstriata have obligate symbiotic relationships with different burrowing echinoids, while Kelliabecki (WH Turton, 1932) and Melliteryxmactroides (Hanley, 1857) are free-living. DNA data and phylogenetic analyses are provided for three of the species.

Spatial decoupling of taxon richness, phylogenetic diversity and threat status in the megagenus Erica (Ericaceae).

Estimates of the number of vascular plant species currently under threat of extinction are shockingly high, with the highest extinction rates reported for narrow-range, woody plants, especially in biodiversity hotspots with Mediterranean and tropical climates. The large genus Erica is a prime example, as a large proportion of its 851 species, all shrubs or small trees, are endemic to the Cape Floristic Region (CFR) of South Africa. Almost two hundred are known to be threatened and a further hundred are 'Data Deficient'. We need to target conservation efforts and research to fill the most problematic knowledge gaps. This can be especially challenging in large genera, such as Erica, with numerous threatened species that are closely related. One approach involves combining knowledge of phylogenetic diversity with that of IUCN threat status to identify the most Evolutionarily Distinct and Globally Endangered (EDGE) species. We present an expanded and improved phylogenetic hypothesis for Erica (representing 65% of described species diversity) and combine this with available threat and distribution data to identify species and geographic areas that could be targeted for conservation effort to maximise preservation of phylogenetic diversity (PD). The resulting 39 EDGE taxa include 35 from the CFR. A further 32 high PD, data deficient taxa are mostly from outside the CFR, reflecting the low proportion of assessed taxa outside South Africa. The most taxon-rich areas are found in the south-western CFR. They are not the most phylogenetically diverse, but do include the most threatened PD. These results can be cross-referenced to existing living and seed-banked ex situ collections and used to target new and updated threat assessments and conservation action.

Deciphering Pteronia's evolution in the Cape Floristic Region: A comprehensive study disputes polyploid deficiency and affirms diploid radiation.

The Greater Cape Floristic Region (GCFR) is renowned for its exceptional biodiversity, accommodating over 11 000 plant species, notable degree of endemism, and substantial diversification within limited plant lineages, a phenomenon ascribed to historical radiation events. While both abiotic and biotic factors contribute to this diversification, comprehensive genomic alterations, recognized as pivotal in the diversification of angiosperms, are perceived as uncommon. This investigation focuses on the genus Pteronia, a prominent representative of the Asteraceae family in the GCFR. Employing NGS-based HybSeq and RADSeq methodologies, flow cytometry, karyology, and ecological modeling, we scrutinize the intricacies of its polyploid evolution. Phylogenetic reconstructions using 951 low-copy nuclear genes confirm Pteronia as a well-supported, distinct clade within the tribe Astereae. The ingroup displays a structure indicative of rapid radiation likely antedating polyploid establishment, with the two main groups demarcated by their presence or absence in the fynbos biome. Genome size analysis encompasses 1293 individuals across 347 populations, elucidating significant variation ranging from 6.1 to 34.2 pg (2C-value). Pteronia demonstrates substantially large genome sizes within Astereae and phanerophytes. Polyploidy is identified in 31% of the studied species, with four discerned ploidy levels (2x, 4x, 6x, 8x). Cytotypes exhibit marked distinctions in environmental traits, influencing their distribution across biomes and augmenting their niche differentiation. These revelations challenge the presumed scarcity of polyploidy in the Cape flora, underscoring the imperative need for detailed population studies. The intricate evolutionary history of Pteronia, characterized by recent polyploidy and genome size variation, contributes substantially to the comprehension of diversification patterns within the GCFR biodiversity hotspot.

Seasonal and trend variation of methane concentration over two provinces of South Africa using Sentinel-5p data

South Africa faces the urgency to comprehensively understand and manage its methane (CH4) emissions. The primary aim of this study is to compare CH4 concentrations between Eastern Cape and Mpumalanga regions dominated by cattle farming and coal mining industries, respectively. CH4 concentration trends were analyzed for the period 2019 to 2023 using satellite data. Trend analysis revealed significant increasing trends in CH4 concentrations in both provinces, supported by Mann–Kendall tests that rejected the null hypothesis of no trend (Eastern Cape: p-value = 8.9018e−08 and Mpumalanga: p-value = 2.4650e−10). The Eastern Cape, a leading cattle farming province, exhibited cyclical patterns and increasing CH4 concentrations, while Mpumalanga, a major coal mining province, displayed similar increasing trends with sharper concentration points. The results show seasonal variations in CH4 concentrations in the Eastern Cape and Mpumalanga provinces. High CH4 concentrations are observed in the northwestern region during the December-January–February (DJF) season, while lower concentrations are observed in the March–April-May (MAM) and June-July–August (JJA) seasons in the Eastern Cape province. In the Mpumalanga province, there is a dominance of high CH4 concentrations in southwestern regions and moderately low concentrations in the northeastern regions, observed consistently across all seasons. The study also showed an increasing CH4 concentration trend from 2019 to 2023 for both provinces. The study highlights the urgent need to address CH4 emissions from both cattle farming and coal mining activities to mitigate environmental impacts and promote sustainable development. Utilizing geographic information system (GIS) and remote sensing technologies, policymakers and stakeholders can identify and address the sources of CH4 emissions more effectively, thereby contributing to environmental conservation and sustainable resource management.

Redefining the megagenus Erica L. (Ericaceae): the contributions of E. G. H. Oliver and I. M. Oliver (née Nitzsche) to taxonomy and nomenclature.

The megagenus Erica L. (Ericaceae), as it is recognised today, includes 851 species of evergreen shrubs or small trees, the majority of which are endemic to the Cape Floristic Region of South Africa. From the first descriptions in Linnaeus's Genera plantarum, a succession of authors ascribed the steadily accumulating numbers of known species to various of a total of 72 different genera. Until the latter half of the twentieth century, so called 'minor genera' such as Philippia Klotzsch and Blaeria L. were still recognised for many African species. The now uncontroversial inclusive circumscription of Erica, and a substantial proportion of its currently recognised species diversity, was conceptualised, described, and illustrated by the South African botanists E. G. H. ('Ted') Oliver and Inge M. Oliver in a succession of works published from 1964 to the present day. We review the historical development of generic delimitation in Erica sens. lat., focusing on the contribution of the Olivers to the current state of systematic knowledge of the genus, and presenting an overview and complete lists of literature and of taxa that they authored.

Developing an electronic portfolio of learning for family medicine training in South Africa.

Workplace-based assessment has become increasingly crucial in the postgraduate training of specialists in South Africa, particularly for family physicians. The development of a Portfolio of Learning (PoL) has been a central focus within the discipline of family medicine for over a decade. Initially, a paper-based portfolio was adopted to collect evidence of learning for 50 out of 85 agreed exit-level outcomes. Stellenbosch University led the conversion of this portfolio into an electronic format, known as e-PoL, utilising Scorion software. The e-PoL was successfully implemented in the Western and Eastern Cape regions and was subsequently adopted nationally under the coordination of the South African Academy of Family Physicians. In 2023, the e-PoL underwent a redesign to gather evidence of learning for 22 entrustable professional activities (EPAs). Key insights from this development process underscore the importance of the PoL in supporting assessment-for-learning rather than merely assessment-of-learning. This necessitates features for feedback and interaction, ensuring that the PoL functions beyond a mere repository of forms. Additionally, the e-PoL should facilitate triangulation, aggregation, and saturation of data points to effectively measure EPAs. Furthermore, the PoL has not only documented learning but has also played a pivotal role in guiding the development of clinical training by explicitly outlining expectations for both registrars and supervisors. While the initial design and development costs are significant, operational costs become affordable when shared across all training programmes.

Micro-analysis of earnings and its determinants in eastern cape province of South Africa

Earnings disparities in South Africa, and specifically the Eastern Cape region are influenced by a complex interplay of historical, socio-economic, and demographic factors. Despite significant progress since the end of apartheid, persistent disparities in earnings continue to raise questions about the effectiveness of policies aimed at reducing inequality and promoting equitable social system. Individual-level dataset from the 2021 South African general household survey were subjected to exploratory analysis, while Heckman selection model was used to investigate the determinants of earnings disparities in the study area. The results showed that majority of the population are not working for a wage, commission or salary, which also pointed to the gravity of unemployment situation in the area of study. Most of the working population (both male and female) are lowest earners (R ≤ 10,000), and this also cuts across all age-group categories. Majority of working population have no formal education, are drop out, or have less than grade-12 certificate, and very few working populations with higher education status were found in the moderate and relatively high earnings categories. While many of the working population are engaged in the informal sector, those in the formal sector are in the lowest earners group. Compared to any other race, the Black African group constituted the majority of non-wage earners, and most in this group were found in the lowest earners group. Some of the working population who were beneficiaries of social grants and medical aids scheme were found in the lowest, low, and moderate earnings categories. The findings significantly isolated the earnings-effect of age, marital status, gender, race, education, geographic indicators, employment sector, and index of health conditions and disabilities. The study recommends interventions addressing racial, gender, and geographic wage gaps, while also emphasizing the importance of equitable access to education, health infrastructure, and skills development.

A new cryptic species in Behria (Asparagaceae, Brodiaeoideae), from the Baja California peninsula, Mexico

Behria is a genus of petaloid geophytes endemic to the Cape Region of Baja California Sur, Mexico. It belongs to the Milla clade within the subfamily Brodiaeoideae of the Asparagaceae family. Currently, Behria tenuiflora is the only recognized species within this genus. In our methodological approach, we considered two distinct floral morphotypes: Group A consists of populations found at lowland elevations (10–150 m), while Group B comprises plants growing at mid to high elevations (400–2060 m). The aim of our study was to investigate whether there are discernible morphological differences and correlations with climate variables between Behria Group A and Group B. To address this, we measured nine quantitative characters for 94 plants from seven populations of Behria tenuiflora. Our findings revealed statistically significant differences (P < 0.05) in pedicel length, perianth length, perianth base diameter, and perianth aperture diameter of the analyzed Behria groups. Based on these results, we propose the recognition of Behria leonis as a new species. Additionally, we provide a morphological key for distinguishing Behria and Bessera genera, along with illustrations, a distribution map, and photographs.

Examining the effects of climate change and human impacts on a high-resolution, late Holocene paleofire record from South Africa's winter rainfall zone

Fire is central to the Cape Floristic Region's highly biodiverse and disturbance-adapted Fynbos Biome. However, prehistoric fire regimes, their ecological consequences, and their relationships with large-scale climate drivers and human activities remain poorly understood. Here, we use a high-resolution sedimentary charcoal record from Verlorenvlei, a coastal lake situated on the west coast, to interrogate links between fire, climate, and pastoralism in the Fynbos Biome. Our record has a robust chronology supported by 24 radiocarbon dates and provides a continuous sedimentary sequence spanning the last 4200 years, documenting fire activity before and after the local arrival of pastoralists in the Verlorenvlei area ∼1500 cal years BP. Fire at Verlorenvlei over the last 4200 years is variable, with relatively low activity until ∼2000 cal years BP, after which variable but generally higher fire activity occurs until the highest period of fire activity from ∼1450 to 1800 CE (∼500–150 cal years BP). The increase in fire activity ∼2000 years ago corresponds with a shift in the diatom assemblage at Verlorenvlei from marine towards brackish and freshwater species, reflecting increased precipitation derived from a strengthening of the southern westerly winds. The peak in fire activity beginning ∼1450 CE (∼500 cal years BP), near the onset of the Little Ice Age, tracks a second diatom-inferred strengthening of the westerly winds. Other southern hemisphere and Antarctic records further corroborate this increased westerly influence after ∼2000 years. Linear regression modeling on the fire record indicates that moisture availability is the primary driver of fire at Verlorenvlei, with little evidence that human populations influenced fire. Our reconstruction suggests that fire activity at Verlorenvlei is limited by moisture availability and that wetter conditions facilitate increased vegetation (i.e., fuel) and intensified fire at this otherwise fuel-limited site. This work has implications for management and conservation decisions in response to future predictions of a warmer and drier climate along South Africa's west coast.

Genome size variation in Cape schoenoid sedges (Schoeneae) and its ecophysiological consequences.

Increases in genome size in plants-often associated with larger, low-density stomata and greater water-use efficiency (WUE)-could affect plant ecophysiological and hydraulic function. Variation in plant genome size is often due to polyploidy, having occurred repeatedly in the austral sedge genus Schoenus in the Cape Floristic Region (CFR), while species in the other major schoenoid genus in the region, Tetraria, have smaller genomes. Comparing these genera is useful as they co-occur at the landscape level, under broadly similar bioclimatic conditions. We hypothesized that CFR Schoenus have greater WUE, with lower maximum stomatal conductance (gwmax) imposed by larger, less-dense stomata. We investigated relationships between genome size and stomatal parameters in a phylogenetic context, reconstructing a phylogeny of CFR-occurring Schoeneae (Cyperaceae). Species' stomatal and functional traits were measured from field-collected and herbarium specimens. Carbon stable isotopes were used as an index of WUE. Genome size was derived from flow-cytometric measurements of leafy shoots. Evolutionary regressions demonstrated that stomatal size and density covary with genome size, positively and negatively, respectively, with genome size explaining 72-75% of the variation in stomatal size. Larger-genomed species had lower gwmax and C:N ratios, particularly in culms. We interpret differences in vegetative physiology between the genera as evidence of more-conservative strategies in CFR Schoenus compared to the more-acquisitive Tetraria. Because Schoenus have smaller, reduced leaves, they likely rely more on culm photosynthesis than Tetraria. Across the CFR Schoeneae, ecophysiology correlates with genome size, but confounding sources of trait variation limit inferences about causal relationships between traits.

Seed banks and post‐fire recovery of invasive alien Metrosideros excelsa in South Africa: Implications for control

AbstractThe New Zealand bottlebrush, Metrosideros excelsa (Myrtaceae), was introduced into South Africa in the 1940s as an ornamental plant and subsequently naturalized in coastal parts of the Cape Floristic Region. Knowledge of M. excelsa's propagule pressure and response to fire in South Africa can inform evaluation of the species' invasion potential and management. We assessed M. excelsa's canopy and soil seed banks in burnt and unburnt stands; and post‐fire regeneration via reseeding and resprouting in relation to fire severity and tree size. Soil seed banks were assessed using an emergence technique, but no seedlings emerged from soil collected under burnt or unburnt plants suggesting that the species does not maintain a viable soil‐stored seed bank or germination triggers were not met (though unlikely). The annual seed crop in the canopies of unburnt trees was approximately 0.5–23 million seeds per tree. Viability, assessed through tetrazolium stain testing, of canopy‐borne seeds on unburnt trees was 18%, whereas a canopy fire, ranging in severity from low to extreme, killed all canopy‐borne seeds. Fifteen months post‐fire, the seedling to pre‐fire (live) tree ratio was 0.01, whereas 43% of burnt trees survived via basal resprouting. Fire severity had a non‐linear effect on tree survival (survival was highest after medium and high fire severity and lowest after low and extreme fire severity), while larger trees were more likely to survive fire. These results suggest that even low‐severity (safe) burning may be a useful control measure as it kills canopy‐borne seeds and causes substantial mortality, particularly of smaller trees. An opportunistic evaluation of an uncontrolled (no comparison with untreated individuals) foliar herbicide application to post‐fire resprouting individuals also showed considerable (91%) mortality. However, rigorous herbicide trials (also with herbicide in conjunction with burning) are required to inform the management of M. excelsa.

Phylogenetic placement of Carex dianae Steud., a sedge endemic to the South Atlantic island of St. Helena

Carex dianae Steud. is an endemic sedge of St. Helena, an isolated island in the South Atlantic. Our study provides the first molecular sequence data for this taxon. We generated sequence data for plastid matK and trnK regions and nuclear internal transcribed spacer and external transcribed spacer regions to determine the placement of C. dianae in the broader Carex phylogeny. The placement of C. dianae falls within Carex sect. Spirostachyae Drejer, and it is sister to a clade including Carex clavata Thunb., Carex aethiopica Schkuhr (both from the Cape region of S. Africa), and Carex gunniana Boott (southern Australia). The existence of three divergent nucleotype groups and two plastotypes is revealed from genetic variation within C. dianae. The results suggest that the ancestor of C. dianae likely originated in the Cape region of South Africa, followed by transoceanic dispersal to St. Helena estimated at 4.4–4.9 million years ago, likely by a bird vector. The most divergent population is that on an isolated hill known as “The Barn”, which may represent a distinct taxon. The existence of highly structured molecular variation within an island only 16 km long is discussed.