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Reconstructing the evolutionary history of species radiations – the impact of hybridisation. Rob Smissen with contributions from Ilse Breitwieser, Leon Perrie , Lara Shepherd, Peter Heenan and others . Leonard Cockayne. HH Allan. Pierre Dansereau.
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Reconstructing the evolutionary history of species radiations – the impact of hybridisation Rob Smissen with contributions from Ilse Breitwieser, Leon Perrie, Lara Shepherd, Peter Heenan and others ...
Leonard Cockayne HH Allan
Pierre Dansereau “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.
“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 1966 N.Z. J. Bot. 4: 559-595.
Helichrysum lanceolatum Anaphalioides bellidioides
Helichrysumlanceolatumx Anaphalioidesbellidioides F1 BC1 BC1
Principal components analysis of AFLP data for mixed population F1 BC1 P1 P1
Pseudopanax and hybridisation (Perrie and Shepherd) P. crassifolius horoeka lancewood P. crassifolius x P. lessonii P. lessonii houpara coastal five-finger
AFLP – NEWHYBRIDS analysis Backcross to F1 Backcross to F2
Phormium (Harakeke: New Zealand flax) P. tenax F1 hybrid P. cookianum
seed pods of typical Phormiumand those of Okiwi Bay P. tenax Structure estimates of ancestry from AFLP data P. cookianum P. tenax Okiwi Bay
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.
Simplified low-copy nuclear gene-tree non-monophyly of duplicated gene copies Arabidopsis Pachycladon Brassica Pachycladon
Raouliaalliance 2n=28+ Anaphalioides Leucogenes Rachelia Ewartia Raoulia Helichrysum
Allopolyploidy followed by aneuploid reduction? Craspedia 2n=22+
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)