Eurasian origin, boreotropical migration and transoceanic dispersal in the pantropical fern genus Diplazium (Athyriaceae). (22nd June 2015)

• Record Type: Journal Article
• Authors: Wei, Ran; Xiang, Qiaoping; Schneider, Harald; Sundue, Michael A.; Kessler, Michael; Kamau, Peris W.; Hidayat, Arief; Zhang, Xianchun
• Is Part Of: Journal of biogeography. Volume 42:Number 10(2015:Oct.)
• Page Start: 1809
• Page End: 1819
• Publication Date: 2015-06-22
• Subjects: Biogeography -- Periodicals; 578.09
• DOI: 10.1111/jbi.12551
• Languages: English
• ISSNs: 0305-0270

Abstract

<abstract abstract-type="main" id="jbi12551-abs-0001"> <title>Abstract</title> <sec id="jbi12551-sec-0001" sec-type="section"> <title>Aim</title> <p>Gondwanan vicariance, boreotropical migration and long‐distance dispersal have been posited as alternative hypotheses explaining the tropical distribution patterns and diversifications in many fern groups. Here, the historical biogeography of <italic>Diplazium</italic> is reconstructed to evaluate the impact of these biogeographical processes in shaping the modern tropical disjunctions.</p> </sec> <sec id="jbi12551-sec-0002" sec-type="section"> <title>Location</title> <p>World‐wide with a focus on tropical forest habitats.</p> </sec> <sec id="jbi12551-sec-0003" sec-type="section"> <title>Methods</title> <p>Divergence times were estimated by analysing nucleotide sequences of seven plastid DNA regions (<italic>atp</italic>A, <italic>atp</italic>B, <italic>mat</italic>K, <italic>rbc</italic>L, <italic>rps</italic>4, <italic>rps</italic>4–<italic>trn</italic>S and <italic>trn</italic>L–F) from 123 species of <italic>Diplazium</italic> and its allied genera, using a Bayesian relaxed clock method and three fossil calibrations. The ancestral areas were reconstructed using the likelihood dispersal–extinction–cladogenesis (DEC) approach.</p> </sec> <sec id="jbi12551-sec-0004" sec-type="section"> <title>Results</title> <p>The crown group of <italic>Diplazium</italic> was estimated to have originated in Eurasia and undergone an initial diversification in the Northern Hemisphere around 41.7 Ma [95% highest posterior density (HPD): 34–49 Ma] during the Eocene. Two disjunct events between the Old and New World were identified: one in subgenus <italic>Diplazium</italic> around the Eocene–Oligocene boundary (31.2 Ma, 95% HPD: 25–38 Ma), and the other in subgenus <italic>Callipteris</italic> during the middle Miocene (12.6 Ma, 95% HPD: 15–23 Ma). Furthermore, Palaeotropical disjunctions in subgenus <italic>Callipteris</italic> are indicative of multiple dispersal events during the Miocene.</p> </sec> <sec id="jbi12551-sec-0005" sec-type="section"> <title>Main conclusions</title> <p>The evolutionary history of <italic>Diplazium</italic> involves a variety of biogeographical scenarios. Early diversification of <italic>Diplazium</italic> in the Northern Hemisphere during the Eocene corresponds with the migration from Eurasia to North America over land bridges as a member of the boreotropical flora. The current tropical amphi‐Pacific disjunctions in subgenus <italic>Diplazium</italic> can be better explained by the disruption of boreotropical belt, however, long‐distance dispersal between Eurasia and tropical America cannot be ruled out. Island‐hopping and trans‐Pacific dispersals followed by speciation characterize the disjunctions and diversifications of subgenus <italic>Callipteris</italic> during the Neogene. Gondwanan vicariance is not supported by any of our results.</p> </sec> </abstract>