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The phylogeography and diversification of an endemic trapdoor spider genus, Stasimopus Simon 1892 (Araneae, Mygalomorphae, Stasimopidae) in the Karoo, South Africa
  • Shannon Brandt,
  • Catherine Sole,
  • Robin Lyle
Shannon Brandt
University of Pretoria

Corresponding Author:[email protected]

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Catherine Sole
University of Pretoria
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Robin Lyle
Agricultural Research Council
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Abstract

Aim: The genus Stasimopus is endemic to South Africa but has never undergone a phylogeographic review. This study aims to unravel the phylogeographic patterns and history of the many Stasimopus species which occur in the greater Karoo region. Location: The Karoo region, South Africa Time period: 2017-2018 Major taxa studied: Cork-lid trapdoor spider, Stasimopus (15 species). Methods: A fossil-calibrated phylogeny was produced based on three gene regions (CO1, 16S and EF-1ɣ) for Stasimopus specimens collected in the Karoo region, to infer dates of origin and diversification. Demographic analyses were performed on species with sufficient sample sizes (>4). Haplotype networks were constructed for each gene region and plotted on a map to infer phylogeographic patterns. Lastly, Mantel tests were performed to test for isolation by distance. Results: It was found that 15 species occur in the Karoo and that the genus radiation in the area is in the early Paleocene. Most diversification occurred between the late Eocene and the Miocene. Several species show signals of demographic expansions. Isolation by distance was detected, but only with a slight correlation. Main conclusions: It is apparent that aridification has played a vital role in the diversification of the genus in the Karoo region. This is a shared biogeographic influence between the mygalomorph fauna of the Karoo and arid region of western Australia. Stasimopus has radiated from the late Eocene and through the Miocene resulting in 15 extant species in the region. The Tankwa Karoo has been identified as a possible Pleistocene glacial cycle refugia for the species S. leipoldti. Many of the species in the Karoo are short range endemics, making them of high conservation concern. This study provided vital information as the Karoo is undergoing further desertification due to factors such as climate change, which may affect the future of short-range endemic spiders.
Submitted to Ecology and Evolution
12 Mar 2024Assigned to Editor
12 Mar 2024Submission Checks Completed
17 Apr 2024Review(s) Completed, Editorial Evaluation Pending
29 Jul 20241st Revision Received
30 Jul 2024Submission Checks Completed
30 Jul 2024Assigned to Editor
30 Jul 2024Review(s) Completed, Editorial Evaluation Pending
09 Aug 2024Reviewer(s) Assigned
04 Oct 2024Editorial Decision: Revise Minor
23 Oct 20242nd Revision Received
31 Oct 2024Submission Checks Completed
31 Oct 2024Assigned to Editor
31 Oct 2024Review(s) Completed, Editorial Evaluation Pending
04 Nov 2024Editorial Decision: Accept