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Abstract

Numerous studies within plant genera have found geographically structured sharing of
chloroplast (cp) DNA among sympatric species, consistent with introgressive hybridization.
Current research is aimed at understanding the extent, direction and significance of
nuclear (nr) DNA exchange that accompanies putative cpDNA exchange. Eucalyptus is a
complex tree genus for which cpDNA sharing has been established between multiple
species. Prior phylogeographic analysis has indicated cpDNA introgression into the
widespread forest species Eucalyptus globulus from its rare congener E. cordata. In this
study, we use AFLP markers to characterize corresponding nrDNA introgression, on both
a broad and fine spatial scale. Using 388 samples we examine (i) the fine-scale spatial
structure of cp and nrDNA introgression from E. cordata into E. globulus at a site in
natural forest and (ii) broad-scale patterns of AFLP marker introgression at six additional
mixed populations. We show that while E. globulus and E. cordata retain strongly
differentiated nuclear gene pools overall, leakage of nrDNA occurs at mixed populations,
with some AFLP markers being transferred to E. globulus recurrently at different sites.
On the fine scale, different AFLP fragments show varying distances of introgression into
E. globulus, while introgression of cpDNA is extensive. The frequency of E. cordata
markers in E. globulus is correlated with spatial proximity to E. cordata, but departs from
expectations based on AFLP marker frequency in E. cordata, indicating that

Item Type:	Article
Authors/Creators:	McKinnon, GE and Smith, JJ and Potts, BM
Keywords:	AFLP, Australia, eucalypt genetics, Eucalyptus, forest, hybridization
Journal or Publication Title:	Molecular Ecology
ISSN:	0962-1083
DOI / ID Number:	10.1111/j.1365-294X.2010.04579.x
Additional Information:	The original publication is available at http://www.interscience.wiley.com/
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