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Support for vicariant origins of the New Zealand Onychophora
Authors:Julia Allwood  Dianne Gleeson  Georg Mayer  Savel Daniels  Jacqueline R Beggs  Thomas R Buckley
Institution:1. Landcare Research, Private Bag 92170, Auckland, New Zealand

School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand;2. Landcare Research, Private Bag 92170, Auckland, New Zealand;3. Department of Anatomy and Cell Biology, University of Melbourne, Melbourne, Vic. 3010, Australia

Department of Genetics, Friedrich-Schiller-Universität Jena, Philosophenweg 12, D-07743 Jena, Germany;4. Department of Botany & Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa;5. School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand

Abstract:Aim The distribution of Onychophora across the southern continents has long been considered the result of vicariance events. However, it has recently been hypothesized that New Zealand was completely inundated during the late Oligocene (25–22 Ma) and therefore that the entire biota is the result of long-distance dispersal. We tested this assumption using phylogenetic and molecular dating of DNA sequence data from Onychophora. Location New Zealand, Australia, South Africa, Chile (South America). Methods We obtained DNA sequence data from the nuclear genes 28S and 18S rRNA to reconstruct relationships among species of Peripatopsidae (Onychophora). We performed molecular dating under a Bayesian relaxed clock model with a range of prior distributions using the rifting of South America and South Africa as a calibration. Results Our phylogenetic trees revealed that the New Zealand genera Ooperipatellus and Peripatoides, together with selected Australian genera (Euperipatoides, Phallocephale and an undescribed genus from Tasmania), form a monophyletic group that is the sister group to genera from Chile (Metaperipatus) and South Africa (Peripatopsis and Opisthopatus). The relaxed clock dating analyses yielded mean divergence times from 71.3 to 78.9 Ma for the split of the New Zealand Peripatoides from their Australian sister taxa. The 0.95 Bayesian posterior intervals were very broad and ranged from 24.5 to 137.6 Ma depending on the prior assumptions. The mean divergence of the New Zealand species of Ooperipatellus from the Australian species Ooperipatellus insignis was estimated at between 39.9 and 46.2 Ma, with posterior intervals ranging from 9.5 to 91.6 Ma. Main conclusions The age of Peripatoides is consistent with long-term survival in New Zealand and implies that New Zealand was not completely submerged during the Oligocene. Ooperipatellus is less informative on the question of continuous land in the New Zealand region because we cannot exclude a post-Oligocene divergence. The great age of Peripatoides is consistent with a vicariant origin of this genus resulting from the rifting of New Zealand from the eastern margin of Gondwana and supports the assumptions of previous authors who considered the Onychophora to be a relict component of the New Zealand biota.
Keywords:Biogeography  dispersal  Gondwana  molecular clock  Oligocene Drowning  Peripatopsidae  peripatus  velvet worms  vicariance
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