reconstructing the evolutionary history of species radiations – the impact of hybridisation rob...
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Reconstructing the evolutionary history of species radiations – the impact of hybridisation
Rob Smissenwith contributions from Ilse Breitwieser, Leon Perrie,
Lara Shepherd, Peter Heenan and others ...
Leonard Cockayne HH Allan
“It is quite possible that no other natural area in the world has as great a number of genera whose definition of species is as badly confused by hybrid swarms”
1964. Bulletin of the Torrey Botanical Club 91: 114-140.
Pierre Dansereau
“The most that can be said about natural hybridisation in the New Zealand flora is that it is well attested in a few genera and is probable in others.”
J.B. Hair 1966N.Z. J. Bot. 4: 559-595.
Helichrysum lanceolatumAnaphalioides bellidioides
Helichrysum lanceolatum x Anaphalioides bellidioides
F1
BC1 BC1
F1BC1
P1
P1
Principal components analysis of AFLP data for mixed population
P. lessoniihoupara
coastal five-finger
P. crassifoliushoroeka
lancewood
P. crassifolius x P. lessonii
Pseudopanax and hybridisation (Perrie and Shepherd)
Backcross toBackcross to F1 F2
AFLP – NEWHYBRIDS analysis
Phormium (Harakeke: New Zealand flax)
P. tenax
P. cookianum
F1 hybrid
P. tenaxP. cookianum
Okiwi Bay
Structure estimates of ancestry from AFLP data
seed pods of typical Phormium and those of Okiwi Bay P. tenax
A contemporary biosystematic view
• Many hybrids well documented, few dismissed
• Geneflow among species seems limited overall
• Neo-allopolyploidy is well evidenced
• Homoploid hybrid species not yet demonstrated
See also, Pelser et al. American Journal of Botany 97(5): 856–873. 2010.
Asplenium polyploid evolution
Pachycladon
Arabidopsis
Pachycladon
Pachycladon
Brassica
Simplified low-copy nuclear gene-treenon-monophyly of duplicated gene copies
Raoulia alliance 2n=28+
Anaphalioides
Rachelia
Leucogenes
Ewartia
Raoulia Helichrysum
Craspedia 2n=22+
Allopolyploidy followed by aneuploid reduction?
Summary – hybridisation in the NZ flroa
•Contemporary hybridisation frequent
•Contemporary gene-flow among species is limited
•Aallopolyploid speciation important in some groups
•Paleo-allo-polyploidy in species rich groups
•Not certain how important homoploid hybrid speciation and introgression have been in species radiations
Acknowledgements
• Ilse Breitwieser & fellow symposium speakers• Mercè Galbany-Casals• NZPRN members• Leon Perrie and Lara Shepherd (for Asplenium and
Pseudopanax)• Peter Heenan (Pachycladon)
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