Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech).
Nothofagus (southern beech), with an 80-million-year-old fossil record, has become iconic as a plant genus whose ancient Gondwanan relationships reach back into the Cretaceous era. Closely associated with Wegener's theory of "Kontinentaldrift", Nothofagus has been regarded as the &quo...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2005-01-01
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| Series: | PLoS Biology |
| Online Access: | https://doi.org/10.1371/journal.pbio.0030014 |
| _version_ | 1818591886728757248 |
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| author | Michael Knapp Karen Stöckler David Havell Frédéric Delsuc Federico Sebastiani Peter J Lockhart |
| author_facet | Michael Knapp Karen Stöckler David Havell Frédéric Delsuc Federico Sebastiani Peter J Lockhart |
| author_sort | Michael Knapp |
| collection | DOAJ |
| description | Nothofagus (southern beech), with an 80-million-year-old fossil record, has become iconic as a plant genus whose ancient Gondwanan relationships reach back into the Cretaceous era. Closely associated with Wegener's theory of "Kontinentaldrift", Nothofagus has been regarded as the "key genus in plant biogeography". This paradigm has the New Zealand species as passengers on a Moa's Ark that rafted away from other landmasses following the breakup of Gondwana. An alternative explanation for the current transoceanic distribution of species seems almost inconceivable given that Nothofagus seeds are generally thought to be poorly suited for dispersal across large distances or oceans. Here we test the Moa's Ark hypothesis using relaxed molecular clock methods in the analysis of a 7.2-kb fragment of the chloroplast genome. Our analyses provide the first unequivocal molecular clock evidence that, whilst some Nothofagus transoceanic distributions are consistent with vicariance, trans-Tasman Sea distributions can only be explained by long-distance dispersal. Thus, our analyses support the interpretation of an absence of Lophozonia and Fuscospora pollen types in the New Zealand Cretaceous fossil record as evidence for Tertiary dispersals of Nothofagus to New Zealand. Our findings contradict those from recent cladistic analyses of biogeographic data that have concluded transoceanic Nothofagus distributions can only be explained by vicariance events and subsequent extinction. They indicate that the biogeographic history of Nothofagus is more complex than envisaged under opposing polarised views expressed in the ongoing controversy over the relevance of dispersal and vicariance for explaining plant biodiversity. They provide motivation and justification for developing more complex hypotheses that seek to explain the origins of Southern Hemisphere biota. |
| first_indexed | 2024-12-16T10:19:34Z |
| format | Article |
| id | doaj.art-99eb1aaa06764be7849e35e514d4bad2 |
| institution | Directory Open Access Journal |
| issn | 1544-9173 1545-7885 |
| language | English |
| last_indexed | 2024-12-16T10:19:34Z |
| publishDate | 2005-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Biology |
| spelling | doaj.art-99eb1aaa06764be7849e35e514d4bad22022-12-21T22:35:21ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852005-01-0131e1410.1371/journal.pbio.0030014Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech).Michael KnappKaren StöcklerDavid HavellFrédéric DelsucFederico SebastianiPeter J LockhartNothofagus (southern beech), with an 80-million-year-old fossil record, has become iconic as a plant genus whose ancient Gondwanan relationships reach back into the Cretaceous era. Closely associated with Wegener's theory of "Kontinentaldrift", Nothofagus has been regarded as the "key genus in plant biogeography". This paradigm has the New Zealand species as passengers on a Moa's Ark that rafted away from other landmasses following the breakup of Gondwana. An alternative explanation for the current transoceanic distribution of species seems almost inconceivable given that Nothofagus seeds are generally thought to be poorly suited for dispersal across large distances or oceans. Here we test the Moa's Ark hypothesis using relaxed molecular clock methods in the analysis of a 7.2-kb fragment of the chloroplast genome. Our analyses provide the first unequivocal molecular clock evidence that, whilst some Nothofagus transoceanic distributions are consistent with vicariance, trans-Tasman Sea distributions can only be explained by long-distance dispersal. Thus, our analyses support the interpretation of an absence of Lophozonia and Fuscospora pollen types in the New Zealand Cretaceous fossil record as evidence for Tertiary dispersals of Nothofagus to New Zealand. Our findings contradict those from recent cladistic analyses of biogeographic data that have concluded transoceanic Nothofagus distributions can only be explained by vicariance events and subsequent extinction. They indicate that the biogeographic history of Nothofagus is more complex than envisaged under opposing polarised views expressed in the ongoing controversy over the relevance of dispersal and vicariance for explaining plant biodiversity. They provide motivation and justification for developing more complex hypotheses that seek to explain the origins of Southern Hemisphere biota.https://doi.org/10.1371/journal.pbio.0030014 |
| spellingShingle | Michael Knapp Karen Stöckler David Havell Frédéric Delsuc Federico Sebastiani Peter J Lockhart Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). PLoS Biology |
| title | Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). |
| title_full | Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). |
| title_fullStr | Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). |
| title_full_unstemmed | Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). |
| title_short | Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). |
| title_sort | relaxed molecular clock provides evidence for long distance dispersal of nothofagus southern beech |
| url | https://doi.org/10.1371/journal.pbio.0030014 |
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