Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition
Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad m...
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Published in | Proceedings of the Royal Society. B, Biological sciences Vol. 280; no. 1768; p. 20131708 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
England
The Royal Society
07.10.2013
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Subjects | |
Online Access | Get full text |
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Summary: | Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic–Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis. |
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Bibliography: | ark:/67375/V84-7XZVQM21-8 ArticleID:rspb20131708 istex:0A6CEFD6B9B6CBE2495603CAC7F041A0EAD1F3FA href:rspb20131708.pdf |
ISSN: | 0962-8452 1471-2954 |
DOI: | 10.1098/rspb.2013.1708 |