Abstract
Recent phylogenetic research indicates that vascular plants evolved from bryophyte-like ancestors and that this involved extensive modifications to the life cycle. These conclusions are supported by a range of systematic data, including gene sequences, as well as evidence from comparative morphology and the fossil record. Within vascular plants, there is compelling evidence for two major clades, which have been termed lycophytes (clubmosses) and euphyllophytes (seed plants, ferns, horsetails). The implications of recent phylogenetic work are discussed with reference to life cycle evolution and the interpretation of stratigraphic inconsistencies in the early fossil record of land plants. Life cycles are shown to have passed through an isomorphic phase in the early stages of vascular plant evolution. Thus, the gametophyte generation of all living vascular plants is the product of massive morphological reduction. Phylogenetic research corroborates earlier suggestions of a major representational bias in the early fossil record. Mega-fossils document a sequence of appearance of groups that is at odds with that predicted by cladogram topology. It is argued here that the pattern of appearance and diversification of plant megafossils owes more to changing geological conditions than to rapid biological diversification.
Full Text
The Full Text of this article is available as a PDF (508.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Duff R. J., Nickrent D. L. Phylogenetic relationships of land plants using mitochondrial small-subunit rDNA sequences. Am J Bot. 1999 Mar;86(3):372–386. [PubMed] [Google Scholar]
- Kranz H. D., Miks D., Siegler M. L., Capesius I., Sensen C. W., Huss V. A. The origin of land plants: phylogenetic relationships among charophytes, bryophytes, and vascular plants inferred from complete small-subunit ribosomal RNA gene sequences. J Mol Evol. 1995 Jul;41(1):74–84. doi: 10.1007/BF00174043. [DOI] [PubMed] [Google Scholar]
- Lewis L. A., Mishler B. D., Vilgalys R. Phylogenetic relationships of the liverworts (Hepaticae), a basal embryophyte lineage, inferred from nucleotide sequence data of the chloroplast gene rbcL. Mol Phylogenet Evol. 1997 Jun;7(3):377–393. doi: 10.1006/mpev.1996.0395. [DOI] [PubMed] [Google Scholar]
- Malek O., Lättig K., Hiesel R., Brennicke A., Knoop V. RNA editing in bryophytes and a molecular phylogeny of land plants. EMBO J. 1996 Mar 15;15(6):1403–1411. [PMC free article] [PubMed] [Google Scholar]
- Manhart J. R. Phylogenetic analysis of green plant rbcL sequences. Mol Phylogenet Evol. 1994 Jun;3(2):114–127. doi: 10.1006/mpev.1994.1014. [DOI] [PubMed] [Google Scholar]
- Nishiyama T., Kato M. Molecular phylogenetic analysis among bryophytes and tracheophytes based on combined data of plastid coded genes and the 18S rRNA gene. Mol Biol Evol. 1999 Aug;16(8):1027–1036. doi: 10.1093/oxfordjournals.molbev.a026192. [DOI] [PubMed] [Google Scholar]
- Poe S., Swofford D. L. Taxon sampling revisited. Nature. 1999 Mar 25;398(6725):299–300. doi: 10.1038/18592. [DOI] [PubMed] [Google Scholar]
- Qiu Y. L., Cho Y., Cox J. C., Palmer J. D. The gain of three mitochondrial introns identifies liverworts as the earliest land plants. Nature. 1998 Aug 13;394(6694):671–674. doi: 10.1038/29286. [DOI] [PubMed] [Google Scholar]
- Raubeson L. A., Jansen R. K. Chloroplast DNA evidence on the ancient evolutionary split in vascular land plants. Science. 1992 Mar 27;255(5052):1697–1699. doi: 10.1126/science.255.5052.1697. [DOI] [PubMed] [Google Scholar]