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1. Complex patterns of Gondwanan biogeography revealed in a dispersal‐limited arachnid

   https://doi.org/10.1111/jbi.14080  

   Derkarabetian, Shahan ; Baker, Caitlin M. ; Giribet, Gonzalo ( March 2021 , Journal of Biogeography)

   We explore the biogeographic history of the Gondwanan lineage Triaenonychidae, a dispersal‐limited arachnid taxon that underwent a recent taxonomic revision based on phylogenomic data. We explicitly test hypotheses related to a biogeographical pattern of ‘common vicariance, rare dispersal’, predicted for dispersal‐limited taxa.

   Continental landmasses of former temperate Gondwanan terranes (southern South America, southern Africa, Madagascar, Australia, New Zealand, and New Caledonia).

   Triaenonychidae, Opiliones, Arachnida.

   Utilizing a recently published phylogenomic data set based on ultra‐conserved elements, we conduct Bayesian divergence dating analyses, ancestral area estimation in a likelihood model testing framework, and analyses of macroevolutionary dynamics. Results are correlated with geological history and palaeoclimate reconstructions to infer biogeographic history and distribution.

   We find that divergence dates of ancestral Triaenonychidae pre‐date continental breakup of Gondwana and could be attributed to palaeoclimatic differentiation across Gondwana. There is evidence for two separate expansion routes that span eastern and western Gondwana corresponding to northern warmer climate and southern cooler climate lineages. Many divergences across intercontinental lineages coincide with the timing of continental fragmentation, supporting vicariance as a dominant force. However, some lineages are supported as obvious examples of rare long‐distance dispersal. Biogeographic results support the predicted pattern of common vicariance and rare dispersal for these dispersal‐limited organisms.

   Vicariance due to continental fragmentation was important in the early diversification of Triaenonychidae. Their unique combination and degrees of dispersal ability and microhabitat preference resulted in complex phylogenetic patterns of geographic distribution not typically seen in other animal taxa. Examining biogeographic patterns across recent studies of arachnid taxa with varying dispersal ability, it is clear that biological characteristics play an important role in the relative importance of dispersal and vicariance (dispersal–vicariance continuum) for any given taxon and can be useful in forming testable a priori hypotheses.

    

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2. Molecular phylogeny and biogeography of the temperate Gondwanan family Triaenonychidae (Opiliones : Laniatores) reveals pre-Gondwanan regionalisation, common vicariance, and rare dispersal

   https://doi.org/10.1071/IS19069  

   Baker, Caitlin M. ; Sheridan, Kate ; Derkarabetian, Shahan ; Pérez-González, Abel ; Vélez, Sebastian ; Giribet, Gonzalo ( January 2020 , Invertebrate Systematics)

   null (Ed.)

   Triaenonychidae Sørensen in L. Koch, 1886 is a large family of Opiliones with ~480 described species broadly distributed across temperate forests in the Southern Hemisphere. However, it remains poorly understood taxonomically, as no comprehensive phylogenetic work has ever been undertaken. In this study we capitalise on samples largely collected by us during the last two decades and use Sanger DNA-sequencing techniques to produce a large phylogenetic tree with 300 triaenonychid terminals representing nearly 50% of triaenonychid genera and including representatives from all the major geographic areas from which they are known. Phylogenetic analyses using maximum likelihood and Bayesian inference methods recover the family as diphyletic, placing Lomanella Pocock, 1903 as the sister group to the New Zealand endemic family Synthetonychiidae Forster, 1954. With the exception of the Laurasian representatives of the family, all landmasses contain non-monophyletic assemblages of taxa. To determine whether this non-monophyly was the result of Gondwanan vicariance, ancient cladogenesis due to habitat regionalisation, or more recent over-water dispersal, we inferred divergence times. We found that most divergence times between landmasses predate Gondwanan breakup, though there has been at least one instance of transoceanic dispersal – to New Caledonia. In all, we identify multiple places in the phylogeny where taxonomic revision is needed, and transfer Lomanella outside of Triaenonychidae in order to maintain monophyly of the family. 

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3. First global molecular phylogeny and biogeographical analysis of two arachnid orders (Schizomida and Uropygi) supports a tropical Pangean origin and mid‐Cretaceous diversification

   https://doi.org/10.1111/jbi.13076  

   Clouse, Ronald M. ; Branstetter, Michael G. ; Buenavente, Perry ; Crowley, Louise M. ; Czekanski‐Moir, Jesse ; General, David Emmanuel M. ; Giribet, Gonzalo ; Harvey, Mark S. ; Janies, Daniel A. ; Mohagan, Alma B. ; et al ( August 2017 , Journal of Biogeography)

   We sought to illuminate the history of the arachnid orders Schizomida and Uropygi, neither of which have previously been subjected to global molecular phylogenetic and biogeographical analyses.

   Specimens used in this study were collected in all major tropical and subtropical areas where they are presently found, including the Americas, Africa, Australia and the Indo‐Pacific region.

   From field‐collected specimens, we sequenced two nuclear and two mitochondrial markers, combined these with publicly available data, and conducted multi‐gene phylogenetic analyses on 240 Schizomida, 24 Uropygi and 12 other arachnid outgroups. Schizomid specimens included one specimen from the small family Protoschizomidae; other schizomid specimens were in Hubbardiidae, subfamily Hubbardiinae, which holds 289 of the order's 305 named species. We inferred ancestral areas using the Dispersal‐Extinction‐Cladogenesis model of range evolution, and we used fossil calibrations to estimate divergence times.

   We recovered monophyletic Schizomida and Uropygi as each other's sister group, forming the clade Thelyphonida, and terminals from the New World were usually positioned as the earliest diverging lineages. The ancestral area for schizomids reconstructed unambiguously to the region comprised of Mexico, Southern California and Florida (the xeric New World subtropics). Optimal trees suggested a single colonization of the Indo‐Pacific in both orders, although this did not receive bootstrap support. Molecular dating gave an Upper Carboniferous origin for each order, and a mid‐Cretaceous expansion of Schizomida, including the origin and initial diversification of those in the Indo‐Pacific.

   Ancestral area reconstructions, molecular dating and fossil evidence all support an Upper Carboniferous, tropical Pangean origin for Thelyphonida, Schizomida and perhaps Uropygi. Much of this region became unsuitable habitat for these arachnids during the breakup of Pangea, but they persisted in the area that is now Meso‐ and South America. From there they then expanded to the Indo‐Pacific, where schizomids today display an idiosyncratic combination of microendemism and long‐range dispersal.

    

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4. Out of India, thrice: diversification of Asian forest scorpions reveals three colonizations of Southeast Asia

   https://doi.org/10.1038/s41598-020-78183-8  

   Loria, Stephanie F. ; Prendini, Lorenzo ( December 2020 , Scientific Reports)

   null (Ed.)

   Abstract The ‘Out of India’ hypothesis is often invoked to explain patterns of distribution among Southeast Asian taxa. According to this hypothesis, Southeast Asian taxa originated in Gondwana, diverged from their Gondwanan relatives when the Indian subcontinent rifted from Gondwana in the Late Jurassic, and colonized Southeast Asia when it collided with Eurasia in the early Cenozoic. A growing body of evidence suggests these events were far more complex than previously understood, however. The first quantitative reconstruction of the biogeography of Asian forest scorpions (Scorpionidae Latreille, 1802: Heterometrinae Simon, 1879) is presented here. Divergence time estimation, ancestral range estimation, and diversification analyses are used to determine the origins, dispersal and diversification patterns of these scorpions, providing a timeline for their biogeographical history that can be summarized into four major events. (1) Heterometrinae diverged from other Scorpionidae on the African continent after the Indian subcontinent became separated in the Cretaceous. (2) Environmental stresses during the Cretaceous–Tertiary (KT) mass extinction caused range contraction, restricting one clade of Heterometrinae to refugia in southern India (the Western Ghats) and Sri Lanka (the Central Highlands). (3) Heterometrinae dispersed to Southeast Asia three times during India’s collision with Eurasia, the first dispersal event occurring as the Indian subcontinent brushed up against the western side of Sumatra, and the other two events occurring as India moved closer to Eurasia. (4) Indian Heterometrinae, confined to southern India and Sri Lanka during the KT mass extinction, recolonized the Deccan Plateau and northern India, diversifying into new, more arid habitats after environmental conditions stabilized. These hypotheses, which are congruent with the geological literature and biogeographical analyses of other taxa from South and Southeast Asia, contribute to an improved understanding of the dispersal and diversification patterns of taxa in this biodiverse and geologically complex region. 

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5. Giant Goblins above the waves at the southern end of the world: The biogeography of the spider family Orsolobidae (Araneae, Dysderoidea)

   https://doi.org/10.1111/jbi.13487  

   Chousou‐Polydouri, Natalia ; Carmichael, Anthea ; Szűts, Tamás ; Saucedo, Alma ; Gillespie, Rosemary ; Griswold, Charles ; Wood, Hannah M. ( January 2019 , Journal of Biogeography)

   As a continental island, much of the biota of New Zealand was initially thought to have been shaped by vicariance. Recent studies, however, have highlighted the role of dispersal, with some even suggesting that the entire biota is the product of dispersal events following emergence of the islands. This study focuses on the interplay between dispersal and vicariance, specifically asking whether the spider family Orsolobidae has Gondwanan origins on New Zealand.

   The spider family Orsolobidae was sampled from all continents where they occur (Africa, Australia, New Zealand and South America), comprising a total of 66 specimens representing the phylogenetic diversity of the family.

   DNAsequences were obtained from six fragments that were subsequently aligned and analysed withMrBayes3.2 andbeast1.8. The phylogeny was calibrated with fossils used as node calibrations, as well as with the substitution rate of Histone H3.

   The orsolobid fauna of each land mass except Australia forms a monophyletic group in our analyses. The divergence dating analysis suggests that diversification of Orsolobidae started at a minimum of 80 Ma, while the New Zealand clade dates from a minimum of 40 Ma.

   Thus, while many taxa have colonized the islands by dispersal, certain lineages, including the Orsolobidae, have clearly been capable of persisting through times of reduced land area.

    

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