Pre‐Pleistocene geological events shaping diversification and distribution of primitively segmented spiders on East Asian margins

Abstract

†Both the have contributed equally to this work ABSTRACT Aim Phylogeographical research in the East Asian continent and islands (East Asian Margins, or EAM) suggests predominant Pleistocene over-water dispersal events from continent to islands, but more ancient biogeographical patterns in EAM remain obscure. We explored biogeographical histories and population genetic structures of the primitively segmented spiders, Heptathela and Ryuthela (Liphistiidae), broadly codistributed across EAM islands. To test competing biogeographical hypotheses, we looked for geohistoric events that may have shaped their distributional patterns.Location Kyushu and Ryukyus.Methods We sampled 17 Heptathela and Ryuthela species on 10 out of 12 EAM islands and sequenced fragments of two mitochondrial and three nuclear genes. We performed phylogenetic, network, time-calibrated and biogeographical analyses to identify lineages, estimate their divergence times, and reconstruct ancestral ranges. We also assessed genetic diversity and historic demography of each lineage.Results Phylogenetic origin of Heptathela + Ryuthela is estimated at 26.6-18.4 Ma (95% HPD) when EAM islands became separated from the continent. The crown ages of Heptathela (18.0-10.7 Ma) and Ryuthela (17.8-8.7 Ma) coincide with the formation of Japan Sea and Okinawa Trough respectively. A split within Ryuthela (13.9-6.0 Ma) coincides with the opening of the Kerama Gap, but a split within Heptathela (18.0-10.7 Ma) pre-dates the formation of the Tokara Gap. Speciation within Heptathela and Ryuthela is relatively recent (6.0-0.3 Ma). Population genetic and demographic results suggest interrupted gene flow within and among islands, with most species exhibiting stable past populations.Main conclusions Historic biogeographical reconstructions strongly suggest predominant vicariant origins of EAM island liphistiids. Restricted gene flow following barrier formation is the dominant speciation force in these spiders. As they never seem to cross bodies of water, their past range expansion, successive fragmentation of EAM, and other vicariant events, must have shaped the detected genetic boundaries among and within islands.

From Gondwana to GAARlandia: Evolutionary history and biogeography of ogre‐faced spiders (Deinopis)

“…Furthermore, within multiple islands, we find genetically unique clades that are separated by barriers such as mountain ranges (Figure ). Similar patterns of high interspecific genetic divergence have been found in dispersal‐limited lineages of spiders, including Mesothelae (Liphistiidae) spiders as well as mygalomorphs (Hamilton, Formanowicz, & Bond, ; Hamilton, Hendrixson, Brewer, & Bond, ; Xu, Liu, Chen, Li, & Kuntner, ; Xu, Liu, Chen, Ono, et al., ; Xu, Liu, Cheng, et al., ; Xu et al., ). These finding provides an additional context in which to explore the origin and age of Caribbean taxa, including the potential impact of geology on phylogeny.…”

Riding the Kuroshio Current: Stepping stone dispersal of the Okinawa tree lizard across the East Asian Island Arc

“…As a corollary, we would expect these first‐diverging lineages to possess higher standing genetic variation (relative to recently isolated demes) as a consequence of their longer period of isolation. This pattern has been shown in lizards (Lin et al., ), frogs (Tominaga, Matsui, Eto, & Ota, ), and spiders (Su, Brown, Chang, Lin, & Tso, ; Xu et al., ).…”

Molecular species delimitation in the primitively segmented spider genusHeptathelaendemic to Japanese islands

“…After detecting conflicts among single-locus delimitation methods, increasing sample size by adding as many taxa/individuals per taxon and loci as possible is considered as a general "good practice" of mitigating conflicts in delimitation (Abdelkrim et al, 2018;Blaimer et al, 2015;Carstens et al, 2013;Lemmon and Lemmon, 2013;McCormack et al, 2013;Ruane, 2015). However, increasing taxa and individuals may not be possibe for the understudied and/or hyperdiverse taxa (Abdelkrim et al, 2018;Lim et al, 2012;Xu et al, 2017Xu et al, , 2016. Furthermre, increasing loci, for example, genomic scale data, is still timeconsuming and expensive, and computationally demanding (Flouri et al, 2018;Leaché et al, 2018;Noguerales et al, 2018).…”