Eurasian origin, boreotropical migration and transoceanic dispersal in the pantropical fern genus Diplazium (Athyriaceae)
Aim: 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 Diplazium is reconstructed to evaluate the impact of...
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Published in | Journal of biogeography Vol. 42; no. 10; pp. 1809 - 1819 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Blackwell Publishing Ltd
01.10.2015
John Wiley & Sons Ltd Wiley Subscription Services, Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Aim: 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 Diplazium is reconstructed to evaluate the impact of these biogeographical processes in shaping the modern tropical disjunctions. Location: World-wide with a focus on tropical forest habitats. Methods: Divergence times were estimated by analysing nucleotide sequences of seven plastid DNA regions (atpA, atpB, matK, rbcL, rps4, rps4-trnS and trnL-F) from 123 species of Diplazium 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. Results: The crown group of Diplazium 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 Diplazium around the Eocene-Oligocene boundary (31.2 Ma, 95% HPD: 25-38 Ma), and the other in subgenus Callipteris during the middle Miocene (12.6 Ma, 95% HPD: 15-23 Ma). Furthermore, Palaeotropical disjunctions in subgenus Callipteris are indicative of multiple dispersal events during the Miocene. Main conclusions: The evolutionary history of Diplazium involves a variety of biogeographical scenarios. Early diversification of Diplazium 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 Diplazium can be better explained by the disruption of boreotropical belt, however, long-distance dispersal between Eurasia and tropical America cannot be ruled out. Islandhopping and trans-Pacific dispersals followed by speciation characterize the disjunctions and diversifications of subgenus Callipteris during the Neogene. Gondwanan vicariance is not supported by any of our results. |
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Bibliography: | ArticleID:JBI12551 Appendix S1 Taxa, voucher information and GenBank accession numbers of specimens used in this study. Appendix S2 Phylogram of Diplazium obtained from Bayesian inference analyses of the combined plastid DNA data set including sequences of atpA, atpB, matK, rbcL, rps4, rps4-trnS and trnL-F. Appendix S3 Additional tables (Tables S1 & S2) and figures (Figs S1-S4). National Science Foundation of China - No. 31170199 External Cooperation Program of Bureau of International Co-operation Chinese Academy of Sciences - No. GJHZ201321 istex:2B79598F790C2140C5DC5BA79284CCEC21BBB897 ark:/67375/WNG-8FR8BB3J-X Editor: Peter Linder |
ISSN: | 0305-0270 1365-2699 |
DOI: | 10.1111/jbi.12551 |