University Of Tasmania
155252 - Molecular insights into the dynamics of species invasion by hybridisation in.pdf (3.88 MB)
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Molecular insights into the dynamics of species invasion by hybridisation in Tasmanian eucalypts

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In plants where seed dispersal is limited compared with pollen dispersal, hybridisation may enhance gene exchange and species dispersal. We provide genetic evidence of hybridisation contributing to the expansion of the rare Eucalyptus risdonii into the range of the widespread E. amygdalina. These closely related tree species are morphologically distinct, and observations suggest that natural hybrids occur along their distribution boundaries and as isolated trees or in small patches within the range of E. amygdalina. Hybrid phenotypes occur outside the range of normal dispersal for E. risdonii seed, yet in some hybrid patches small individuals resembling E. risdonii occur and are hypothesised to be a result of backcrossing. Using 3,362 genome-wide SNPs assessed from 97 individuals of E. risdonii and E. amygdalina and 171 hybrid trees, we show that (i) isolated hybrids match the genotypes expected of F1/F2 hybrids, (ii) there is a continuum in the genetic composition among the isolated hybrid patches from patches dominated by F1/F2-like genotypes to those dominated by E. risdonii-backcross genotypes; and (iii) the E. risdonii-like phenotypes in the isolated hybrid patches are most-closely related to proximal larger hybrids. These results suggest that the E. risdonii phenotype has been resurrected in isolated hybrid patches established from pollen dispersal, providing the first steps in its invasion of suitable habitat by long-distance pollen dispersal and complete introgressive displacement of E. amygdalina. Such expansion accords with the population demographics, common garden performance data and climate modelling which favours E. risdonii and highlights a role of interspecific hybridisation in climate change adaptation and species expansion.


Australian Research Council


Publication title

Molecular Ecology






School of Natural Sciences


Wiley-Blackwell Publishing Ltd.

Place of publication

United Kingdom

Rights statement

© 2023 The Authors. Molecular Ecology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY 4.0) License, ( which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Repository Status

  • Open

Socio-economic Objectives

Native forests; Expanding knowledge in the biological sciences