Population genomics of post-glacial western Eurasia.

Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations

The faunistic diversity of spiders (Arachnida: Araneae) of the Savannah Biome of South Africa

Invertebrates include more than 80% of all animals, yet they are severely under-represented in studies of southern African diversity. Site biodiversity estimates that ignore invertebrates, not only omit the greatest part of what they are attempting to measure, but also neglect major contributors to essential ecosystem processes. All available information on spider species distribution in the South African Savanna Biome was compiled. This is the largest biome in the country, occupying over one third of the surface area.Atotal of 23 739 records from 1260 localities were recorded in the South African Savanna Biome until the end of 2010. This included 1230 species represented by 381 genera and 62 families. The last decade has seen an exponential growth in the knowledge of the group in South Africa, but there certainly are several more species that have to be discovered, and the distribution patterns of those listed are partly unknown. Information is summarised for all quarter-degree squares of the biome and reveals considerable inequalities in knowledge. At a large scale the eastern region is much better surveyed than the western parts, but at finer scales throughout the region, several areas have little information. The Salticidae is the most diverse family (162 spp.) and also has the most endemic savanna species (42 spp.). An endemicity index indicates that 366 species are endemic to the biome, with 322 species that are near endemics, i.e., also occurring in an adjacent biome. An abundance index (1–3) was also calculated for each species based on numbers sampled. A rarity index for each species gives a preliminary indication of their conservation importance. Patterns of guild composition are summarised and species known to play a role as predators in agro-ecosystems found within the biome are also discussed.Center for Invasion Biolog

The South African National Red List of spiders: patterns, threats, and conservation

Triage in conservation biology necessitates the prioritization of species and ecosystems for conservation. Although highly diverse, ecologically important, and charismatic, spiders are rarely considered. With 2,253 known species, South Africa's spider diversity is among the highest in the world. A 22-year initiative culminating in a national assessment of all the South African species saw a 33% increase in described species and a 350% rise in specimen accessions of the national collection annually. Endemism is high, at 60% of all South African species. Levels of endemicity are particularly high in Fynbos, Succulent Karroo and Forests. Relative to its area, Forests have three times more endemics than any of the other biomes, followed by the Indian Ocean Coastal Belt. A total of 127 species (5.7%) are either rare or endangered. Threats to these species are largely linked to habitat destruction in the form of urbanization and agriculture. The bulk (62.8%) of taxa are of least concern, but many species are data deficient (27%). Predicted large-scale diversity patterns are confounded by the localised nature of distribution records. Best estimates of compositional turnover point to an east-west bias in our understanding and conservation of spiders in the country, a bias that is most acute in the north-western parts of the country because this region has seen less collecting and has fewer conservation estates. In general, rare and threatened species are mainly ground-dwelling taxa that are either relictual or have poor dispersal abilities. Complemented with long-term surveys that will provide insights into population dynamics of spiders, exploring the use of species traits in predicting extinction probability could provide additional criteria for conservation prioritization. Based on these assessments, targeted species-level interventions might provide a platform for more public awareness and institutional involvement

Soil biota in a megadiverse country: Current knowledge and future research directions in South Africa

Soils are integral to agricultural productivity, biodiversity, and the maintenance of ecosystem services. However, soil ecosystem research depends on foundational biological knowledge that is often missing. In this review, we present a comprehensive, cross-taxa overview of the soil biota of South Africa. We discuss the literature and sampling methods used to assess soil biota, the available taxonomic expertise and main collections within South Africa, the availability of identification guides and online resources, and the status and distribution of described species. We include species lists for all South African soil biota and, for groups with sufficient distribution records, species richness maps. Despite South Africa being only 0.8% of the earth’s terrestrial area, it contains nearly 1.8% of the world’s described soil species (mean per taxon 3.64%, range 0.17–15%; n = 36 groups), with nematodes and earthworms showing a remarkable (6.4 and 7.7%) proportion of globally described diversity. Endemism is high for most groups, ranging from 33–92%. However, major knowledge gaps exist for most soil biota groups. While sampling has been relatively comprehensive in some areas for a few groups (particularly those with direct socioeconomic impacts), the Nama-Karoo, Northern Cape and Eastern Cape are poorly sampled. Natural soils in biodiversity hotspots, such as the Fynbos Biome, are also understudied. We argue that a more integrative approach to acquiring foundational knowledge in soil biodiversity is needed if applied soil research is to be effective in ensuring sustainable soil health. Considerable investment will be required to bring our understanding of the soil biodiversity in this megadiverse region to a level where the Millennium Development Goals can be reached