New Insight Into the Evolutionary Arms Race Between Spider Egg Sac Pseudoparasitoids and Active Maternal Care by the Spiders

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  New Insight Into the Evolutionary Arms Race Between Spider Egg Sac Pseudoparasitoids and Active Maternal Care by the Spiders ABSTRACT Pseudoparasitoids can lead to high mortality in spider egg sacs, and in some cases, they reduce the reproductive success of a spider female to zero. On the other hand, a species that develops within the spider's egg sac uses a limited resource derived from a single egg sac for its larval development. Therefore, the most crucial behaviour that increases the fitness of free-living pseudoparasitoid females is choosing the best host for their offspring. We analysed various points of the counter-adaptations of the spider egg sac pseudoparasitoid and spiders exhibiting active maternal care, utilising the ichneumonid  Hidryta fusiventris  (Thomson, 1873) and the wolf spider  Pardosa lugubris  (Walckenaer, 1802). We showed that the oviposition decision of  H. fusiventris  is based on the spider's egg sac size and that the fema...

Completing the web: identifying sampling bias and knowledge gaps within South African spider surveys (Arachnida, Araneae)

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Completing the web: identifying sampling bias and knowledge gaps within South African spider surveys (Arachnida, Araneae)

Abstract

Species distribution datasets are fundamental for macroecological studies, although there is an overarching need to ensure that these datasets are representative of the entire community. Shortfalls, or knowledge gaps, within biodiversity datasets originate for a range of reasons, and can lead to incorrect conclusions or recommendations being drawn. Spatial scale influences the interpretations of diversity patterns and thus is an important aspect to consider. South Africa has a rich history of spider sampling and as such, it is possible to investigate the influence that scale, both spatial and taxonomic, has on the overall interpretations of how complete the spider knowledge base is in the country. To do this, we draw on curated natural history spider collections and determine how complete the spider assemblages are across twelve unique combinations of taxonomic and spatial scales. Overall, we received 121 605 usable records from seven collections, with spider records and diversity, being concentrated along the eastern and coastal regions of South Africa. We show that assemblage completeness increases with both increasing taxonomic and spatial scales, and as such, knowledge of the distribution of spider families at the biome level is largely complete. Moreover, we show that our fine-scale knowledge of spider assemblages in South Africa is relatively poor, yet we do identify, even at fine scales, assemblages in South Africa that can be considered complete. We identify under-sampled regions of the country, which in turn are congruent with the distribution of under-sampled regions found in other South African invertebrate groups. We show that the scaling of completeness can only be interpreted in one direction: as scale increases so does completeness. These findings will have important implications for spider research and conservation in South Africa, given that regions where completeness is highest correspond strongly to areas in South Africa with the highest threats to biodiversity.

van der Mescht AC, Haddad CR, Foord SH, Dippenaar-Schoeman AS (2024) Completing the web: identifying sampling bias and knowledge gaps within South African spider surveys (Arachnida, Araneae). African Invertebrates 65(2): 223-246. https://doi.org/10.3897/afrinvertebr.65.138881