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Abstract AimWe explored the extent to which Gondwanan vicariance contributed to the circum‐Antarctic distribution of the mite harvestman family Pettalidae, a group of small, dispersal‐limited arachnids whose phylogeny has been poorly resolved, precluding rigorous biogeographic hypothesis testing. LocationContinental landmasses of former temperate Gondwana (Chile, South Africa, Sri Lanka, Australia and New Zealand). TaxonPettalidae, Opiliones. MethodsWe generated transcriptomes for a phylogeny of 16 pettalids, spanning 9 genera. Data were analysed using maximum likelihood, Bayesian inference and coalescence methods. The phylogenetic position of the Sri Lankan genusPettaluswas further explored using quartet likelihood mapping and changes in gene likelihood scores. We also estimated divergence times and looked for signatures of extinction across Antarctica and central Australia using previously published phylogenies with near‐complete species sampling constrained to match our transcriptomic results. Finally, we estimated ancestral ranges and inferred instances of vicariance. ResultsWe recovered a well‐supported topology with a division between taxa from landmasses that made up East Gondwana, and a grade of taxa from West Gondwana.Pettaluswas resolved either as the sister group of the Queensland‐endemicAustropurcellia, or as the sister group to a larger clade from East Gondwana, though favouringPettalus + Austropurcellia. Divergence times for multiple vicariance events coincided with Gondwana's breakup. Speciation–extinction analysis found one diversification process for the family: an initial burst of cladogenesis that slowed down through time. Main ConclusionsGiven that the order of cladogenesis corresponds to the order in which Gondwana fragmented, and the concurrent timing of vicariance and rifting, Gondwanan breakup explains major biogeographic patterns in Pettalidae. Some divergences predate initial rifting, but there is no evidence oftrans‐oceanic dispersal. The Sri Lanka–eastern Australia relationship makes sense in the light of large‐scale extinction across Antarctica and central Australia; however, we find no clear signatures of mass extinction.
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Complex patterns of Gondwanan biogeography revealed in a dispersal‐limited arachnid
Abstract AimWe 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. LocationContinental landmasses of former temperate Gondwanan terranes (southern South America, southern Africa, Madagascar, Australia, New Zealand, and New Caledonia). TaxonTriaenonychidae, Opiliones, Arachnida. MethodsUtilizing 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. ResultsWe 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. Main conclusionsVicariance 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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- Award ID(s):
- 1754278
- PAR ID:
- 10450775
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Biogeography
- Volume:
- 48
- Issue:
- 6
- ISSN:
- 0305-0270
- Format(s):
- Medium: X Size: p. 1336-1352
- Size(s):
- p. 1336-1352
- Sponsoring Org:
- National Science Foundation
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