Land snail biogeography and endemism in south-eastern Africa: Implications for the Maputaland-Pondoland-Albany biodiversity hotspot

[82], also leaving ancient Gondwanan geographical relicts in isolated forest patches due to the relative stability in climate within them [13, 34, 83]. The role of ecological stability of forest habitats in promoting radiation of relictual taxa has been recognised [84], while this phenome- non has also been documented for land snails in forest refugia along the Albertine rift valley of Africa [85], which can be attributed to the ecophysiology of land snails, including their prefer- ence for habitats with high micro-habitat complexity, high humidity, low temperature and damp soil with decaying organic matter [86–88]. The southern escarpment subdominion, possibly a partial recovery in the present analysis corresponds to the lower Karoo bioregion. The MPA-Knysna province indicates an extension of MPA elements into the Cape, which is distinct from the original delimitation of the MPA hotspot. The Knysna unit spatially represents the eastern section of the CFR biodiversity hot- spot, characterized by the Fynbos biome. The similarities of the malacofauna of the Knysna OGU (eastern CFR) with further eastward OGUs are associated with the presence of forest patches in them, despite the Knysna OGU being dominated by Fynbos. This can be attributed to the post-glacial expansion of Afromontane forests to the Knysna-Tsitsikamma area [80, 89]. Overall similarities in the present regionalisation to that for vertebrates [24], despite fine scale differences likely caused by life history attributes such as body size and dispersal ability [90],

suggest a common zoogeographical pattern for both invertebrates and vertebrates in SEA, while biogeographic patterns available for plant assemblages in southern Africa also support similarities [91]. This opens up avenues for future studies incorporating more invertebrate taxa, where there is adequate spatial data and a sufficiently robust taxonomy, and for cross taxon analyses involving both a wide suite of animal and plant lineages. Furthermore, the con- sensus for an extension of the MPA into the Knysna OGU in both vertebrate and land snail Fig 7. Spatial patterns of land snail fauna in south-eastern Africa (SEA). Species richness for the whole study area and all spatial measures on endemism for the SEA dominion (see Fig 2). (a) species richness, (b) SEA dominion endemism, (c) narrow endemism, (d) weighted endemism and (e) corrected weighted endemism. See text for details on above calculations. The whole (blue) line indicates the Maputaland-Pondoland-Albany (MPA) hotspot boundary while the dashed (black) line delimits the Greater MPA region of land snail endemism. The MPA hotspot boundary is reprinted from Hoffman et al. [26] (public domain). https://doi.org/10.1371/journal.pone.0248040.g007 PLOS ONE Land snail endemism in the Maputaland-Pondoland-Albany biodiversity hotspot PLOS ONE | https://doi.org/10.1371/journal.pone.0248040 March 4, 2021 16 / 26