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Dryad

Global expansion of a solitary-social tropical spitting spider shaped by multiple long-distance dispersals

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Jan 19, 2023 version files 3.85 MB

Abstract

The spitting spider Scytodes fusca is well known species complex for its unusual hunting technique which involves spitting a venomous sticky silken substance over its prey. Previous studies supposed that S. fusca was native to Central and Southern America but had been expanded to the tropics of almost every continent. We aimed to test the hypothesis of a Neotropical origin for this spider followed by a secondary dispersal to other regions, and to discuss how population expansion occurred in the tropics was driven. We investigated the population structure and spatiotemporal biogeography of the species complex through a culmination of a 22-year comprehensive global sampling using the mitochondrial and nuclear loci (COI, 16S, 18S, 28S, H3 and ITS2). The S. fusca species complex is divided into two clades. One clade comprises the haplotypes from Australasian regions and a haplotype from Baja Peninsula, Mexico. The other is composed of the haplotypes from all analyzed regions including Asia, Australia, the Americas and Madagascar. The Americas and Madagascar populations exhibit a lower genetic diversity compared with the Australasian population, and both have different population demographic histories. The initial divergence within the species complex started during the early Miocene. Diversifications of both clades occurred during the late Miocene. One haplotype was recently and widely dispersed into Southeast Asia, South Asia, Australia, the Americas and Madagascar. Our results elucidate the global spread history of the S. fusca species complex, suggesting a Malay Archipelago origin, two expansion routes, and its multiple dispersals into the Americas that stem from a common native source population, as well as from Australia, Fiji, French Polynesia, or Turks and Caicos bridgeheads. Our data support that the expansion of the S. fusca species complex from Australasia to America and Madagascar was facilitated by long-distance jump dispersal events.