Renewed management system and provisions for South Africa's sub-Antarctic islands

A novel environmental management plan (EMP) produced for the Prince Edward Islands provides a systematic and comprehensive set of provisions for the management of the islands' biodiversity and historical estate. The plan addresses four major management goals: administration, conservation management, historical conservation and waste management. The EMP serves both an information-provision and a management-support function within a framework of continual improvement

Species richness, environmental correlates, and spatial scale: A test using South African birds

Energy and habitat heterogeneity are important correlates of spatial variation in species richness, though few investigations have sought to determine simultaneously their relative influences. Here we use the South African avifauna to examine the extent to which species richness is related to these variables and how these relationships depend on spatial grain. Taking spatial autocorrelation and area effects into account, we find that primary productivity, precipitation, absolute minimum temperature, and, at coarser resolutions, habitat heterogeneity account for most of the variation in species richness. Species richness and productivity are positively related, whereas the relationship between potential evapotranspiration (PET) and richness is unimodal. This is largely because of the constraining effects of low rainfall on productivity in high-PET areas. The increase in the importance of vegetation heterogeneity as an explanatory variable is caused largely by an increase in the range of vegetation heterogeneity included at coarse resolutions and is probably also a result of the positive effects of environmental heterogeneity on species richness. Our findings indicate that species richness is correlated with, and hence likely a function of, several variables, that spatial resolution and extent must be taken into account during investigations of these relationships, and that surrogate measures for productivity should be interpreted cautiously

Genetic evidence confirms the origin of the house mouse on sub-Antarctic Marion Island

Biological invasions and climate change are two of the largest threats to biodiversity, and this is especially true for island ecosystems that have largely evolved in isolation. The house mouse is considered to have been introduced to sub-Antarctic Marion Island by sealers in the early 1800s. It is currently widespread across the island and has a large impact on the indigenous biota. To date, little information is available on genetic aspects of biological invasions in the sub-Antarctic. Ten specimens of the house mouse were collected from two geographically separated localities on Marion Island. Sequences of the mitochondrial DNA control region revealed only two haplotypes, separated by a single site change. More importantly, these haplotypes are shared between the eastern and western side of Marion Island. By comparing our sequences to data available on GenBank, we provide evidence that house mice on Marion Island is Mus musculus domesticus (Rutty 1772), and most closely related to haplotypes characterizing this species from Denmark, Sweden, Finland, and northern Germany.Ctr Invas Bio

Body size patterns in Drosophila inhabiting a mesocosm: interactive effects of spatial variation in temperature and abundance

Body size is a major component of fitness. However, the relative contributions of different factors to optimal size, and the determinants of spatial and temporal variation in size, have not been fully established empirically. Here, we use a mesocosm of a Drosophilidae assemblage inhabiting decaying nectarines to investigate the influence of spatial variation in temperature on adult body size in Drosophila simulans Sturtevant. Two treatments were established; one in the sun where developing larvae were exposed to high temperatures and the other in the shade where temperature conditions were milder. The simple developmental effects of temperature differences (i.e. larger flies are likely to emerge from cooler environments), or the simple effects of stressful temperatures (i.e. high temperatures yield wing abnormalities and smaller flies), were overridden by interactive effects between temperature and larval density. Emergences were lower in the sun than shade, probably as a result of temperature-induced mortality. However, flies attained the same final sizes in the shade and sun. In addition, abnormally winged flies were clustered in the shaded treatments. In the shade treatments, where emergences were higher than in the sun, stressful conditions as a result of high larval density likely resulted in wing abnormalities and small size. Consequently, there was little spatial variation in size across the mesocosm, but substantial spatial variation in abundance. Under natural conditions both mortality and non-lethal effects of temperature and/or crowding are likely to play a role in the evolution of body size.Ctr Invas Bio

Population structure, propagule pressure, and conservation biogeography in the sub-Antarctic: lessons from indigenous and invasive springtails

The patterns in and the processes underlying the distribution of invertebrates among Southern Ocean islands and across vegetation types on these islands are reasonably well understood. However, few studies have examined the extent to which populations are genetically structured. Given that many sub-Antarctic islands experienced major glaciation and volcanic activity, it might be predicted that substantial population substructure and little genetic isolation-by-distance should characterize indigenous species. By contrast, substantially less population structure might be expected for introduced species. Here, we examine these predictions and their consequences for the conservation of diversity in the region. We do so by examining haplotype diversity based on mitochondrial cytochrome c oxidase subunit I sequence data, from two indigenous (Cryptopygus antarcticus travei, Tullbergia bisetosa) and two introduced (Isotomurus cf. palustris, Ceratophysella denticulata) springtail species from Marion Island. We find considerable genetic substructure in the indigenous species that is compatible with the geological and glacialogical history of the island. Moreover, by employing ecological techniques, we show that haplotype diversity is likely much higher than our sequenced samples suggest. No structure is found in the introduced species, with each being represented by a single haplotype only. This indicates that propagule pressure is not significant for these small animals unlike the situation for other, larger invasive species: a few individuals introduced once are likely to have initiated the invasion. These outcomes demonstrate that sampling must be more comprehensive if the population history of indigenous arthropods on these islands is to be comprehended, and that the risks of within- and among-island introductions are substantial. The latter means that, if biogeographical signal is to be retained in the region, great care must be taken to avoid inadvertent movement of indigenous species among and within islands. Thus, quarantine procedures should also focus on among-island movements.Ctr Invas Bio

Intraspecific Body Size Frequency Distributions of Insects

Although interspecific body size frequency distributions are well documented for many taxa, including the insects, intraspecific body size frequency distributions (IaBSFDs) are more poorly known, and their variation among mass-based and linear estimates of size has not been widely explored. Here we provide IaBSFDs for 16 species of insects based on both mass and linear estimates and large sample sizes (n≥100). In addition, we review the published IaBSFDs for insects, though doing so is complicated by their under-emphasis in the literature. The form of IaBSFDs can differ substantially between mass-based and linear measures. Nonetheless, in non-social insects they tend to be normally distributed (18 of 27 species) or in fewer instances positively skewed. Negatively skewed distributions are infrequently reported and log transformation readily removes the positive skew. Sexual size dimorphism does not generally cause bimodality in IaBSFDs. The available information on IaBSFDs in the social insects suggests that these distributions are usually positively skewed or bimodal (24 of 30 species). However, only c. 15% of ant genera are polymorphic, suggesting that normal distributions are probably more common, but less frequently investigated. Although only 57 species, representing seven of the 29 orders of insects, have been considered here, it appears that whilst IaBSFDs are usually normal, other distribution shapes can be found in several species, though most notably among the social insects. By contrast, the interspecific body size frequency distribution is typically right-skewed in insects and in most other taxa

Using near‐ground leaf temperatures alters the projected climate change impacts on the historical range of a floristic biodiversity hotspot

This is the final version. Available from Wiley via the DOI in this record. DATA AVAILABILITY STATEMENT: All datasets used are third-party datasets available freely on public repositories. The occurrence data for plant species in the Cape floristic Region are freely available from the Global Biodiversity Information Facility (www.gbif.org), and the occurrence data used in this study is available at: https://doi.org/10.5281/zenodo.6374097; the hourly climate data are available from the ERA5 fifth-generation ECMWF atmospheric reanalysis of the global climate (https://cds. climate.copernicus.eu/cdsapp#!/home); hourly near-ground temperatures are fully reproducible using the microclimf package for R 4.0 (https://mrke.github.io); temperature data from the Cederberg used for verification were sourced via the SOILTEMP global database of soil temperatures (https://soiltemp.weebly.com/). All figures created for this study are also available on Figshare (private link: https:// figshare.com/s/d40f9cb44441b252318c).Aim: Species distribution models (SDMs) have been used widely to predict the responses of species to climate change. However, the climate data used to drive these models typically represents ambient air temperatures, derived from measurements taken 1–2 m above the ground. Most plant species live near the ground where temperatures can differ significantly, owing to the effects of solar radiation and reduced wind speed. Here, we investigate differences in spatio-temporal patterns in near-ground leaf and ambient air temperatures and the implications this has on projected changes in species richness of a suite of Fynbos plant species. Location: Fynbos Biome, South Africa. Methods: For each individual plant species (n = 83), we constructed two types of SDMs: one using ambient air temperatures and one using near-ground leaf temperatures. Each of these models was fitted to species occurrence data for a recent time period and projected backwards into the past. Species richness projections for both time periods were then constructed using binarized projections. Results: We found that the impact of climate change on species richness – both the degree of suitable climate lost from the historical range and gained outside of the historical range – was greater using SDMs built with near-ground leaf temperatures. Independent validation of the hindcast projections revealed near-ground SDMs to be more accurate. Main Conclusions: Our study suggests that SDMs constructed using ambient air temperatures are likely overestimating the breadth of the species’ occupied thermal niche, thus underestimating the climate change-driven risk to species where near-ground leaf and ambient air temperatures are particularly decoupled from one another. Additionally, ambient air SDMs may be underestimating the ex-situ refugial potential of inland mountains. Ambient air temperatures should not be considered an effective surrogate for investigating climate change impacts on species living near the ground