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Co-evolution of ferns and mycorrhizae: Phylogenic and morphological trends.

Co-evolution of ferns and mycorrhizae: Phylogenic and morphological trends. Timothy Perez 5/4/10. Overview. Background Why? Evidence? Patterns? Conclusions that can be drawn. Background. (Read et al. 2000). (Read et al. 2000). (Selosse and Le Tacon, 1998).

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Co-evolution of ferns and mycorrhizae: Phylogenic and morphological trends.

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  1. Co-evolution of ferns and mycorrhizae: Phylogenic and morphological trends. Timothy Perez 5/4/10

  2. Overview • Background • Why? • Evidence? • Patterns? • Conclusions that can be drawn

  3. Background (Read et al. 2000) (Read et al. 2000) (Selosse and Le Tacon, 1998)

  4. Why would mycorrhizae co-evolve with ferns? • Increased absorption into fern rhizomes (2) • Subterranean gametophyte nutrients (2) (Smith et al. 2006)

  5. What is Evidence for co-evolution? • Read et al. 2000: down regulation pathogen response in plants • Simon et al. 1993 determined approximate VAM origin to be 462-353 Myr. (3)

  6. Methods: • SSU rRNA from 12 Glomalean VAM species • Homogeneity rate • Calibration checkpoints of 200Myr and 1000Myr. Results: (Simon, Luc et al. 1993)

  7. Conclusion: • Within range of 462-353 Myr. land plants also evolved suggesting VAM importance in land colonization (Simon, Luc et al. 1993)

  8. What pattern and/or generalizations can be made? • Boullard’s, 1979 observations

  9. What patterns and generalizations can be made? • B. Boullard, 1979: Considerations sur la symbiose fongique chez les pteridophytes • Primitive ferns had higher frequency of mycorrhizae than derived. • From primitive to ‘higher’ fern gametophytes we see reduction in mycorrhizal association, reduction is size, and chlorophyll • Read et al, 2000, and Brundrett, 2002 support

  10. To good to be true? • Gemma et al. 1992. Mycorrhizae in Hawaiian Pteridophtyes: Occurrence and Evolutionary Significance Asplenium adiantum-nigrum vesicles, hyphal coils and arbuscles (Gemma et al,1993)

  11. Methods • Sampled 45% of HI fern species for mycorrhizae • Stained roots to determine mycorrhizal colonization density (scale of 1.0-3.0) • Mycorrhizal index (MI) was determined by averaging colonization for each species and for each family (MIF)

  12. Results and Conclusions: • Highest VAM frequency occurred in Dicksoniacea, Dryopteridaceae, Dennstaedtiaceae and Lindsaeaceae • Greatest MI in terricolous species, with next highest frequencies in epiphytic and epilithic ferns • None in Polypodiaceae • Equal distribution of mycorrhizae within ‘primitive’ and ‘higher’ ferns

  13. Conclusions on Generalizations: • A proposed HI phylogeny based on mycorrhizae isn’t consistent with Smith et al. 2006. • Contradicting evidence discounts Boullard, 1979 • More information is needed. (Gemma et al. 1993)

  14. Works Cited: 1: Read, D.J. et al. 2000. Symbiotic fungal associations in ‘lower’ land plants. Philosophical Transactions of the Royal Society B: Biological Sciences. 335: 815-831. 2:Mark C. Brundrett. 2002. Coevolution of roots and mycorrhizas of land plants. New Phytologist. 154: 275-304. 3: Simon, Luc et al. 1993. Origin and diversification of endomycorrhizal fungi and coincidence with vascular plants. Nature. 363: 67-69. 4: Boullard, Bernard. 1979. Considerations sur la symbiose fongique chez les Pteridophytes. Syllogeus. 19. 5: Gemma et al. 1992. Mycorrhizae in Hawaiian Pteridophtyes: Occurrence and Evolutionary Significance. J. Am. Botany. 79:8, 843-852. 6: M-A Selosse and F. Le Tacon. 1998. The land flora: a photroph-fungus partnership? TREE. 13:1, 15-20. 7: Smith et al. 2006. A classification for extant ferns. Taxon. 55:3, 705-731.

  15. Questions?

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