Human-impacted landscapes facilitate hybridization between a native and an introduced tree
Article first published online: 1 MAR 2012
© 2012 Blackwell Publishing Ltd. This is an open access article under the terms of the Creative Commons Attribution Non Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Volume 5, Issue 7, pages 720–731, November 2012
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How to Cite
Hoban, S. M., McCleary, T. S., Schlarbaum, S. E., Anagnostakis, S. L. and Romero-Severson, J. (2012), Human-impacted landscapes facilitate hybridization between a native and an introduced tree. Evolutionary Applications, 5: 720–731. doi: 10.1111/j.1752-4571.2012.00250.x
- Issue published online: 30 OCT 2012
- Article first published online: 1 MAR 2012
- Received: 16 November 2011 Accepted: 20 December 2011
- anthropogenic disturbance;
- interspecific hybridization;
Spatial and temporal dynamics of hybridization, in particular the influence of local environmental conditions, are well studied for sympatric species but less is known for native-introduced systems, especially for long-lived species. We used microsatellite and chloroplast DNA markers to characterize the influence of anthropogenic landscapes on the extent, direction, and spatial distribution of hybridization between a native North American tree Juglans cinerea (butternut) and an introduced tree Juglans ailantifolia (Japanese walnut) for 1363 trees at 48 locations across the native range of butternut. Remarkably, admixture in anthropogenic sites reached nearly 70%, while fragmented and continuous forests showed minimal admixture (<8%). Furthermore, more hybrids in anthropogenic sites had J. ailantifolia seed parents (95%) than hybrids in fragmented and continuous forests (69% and 59%, respectively). Our results show a strong influence of landscape type on rate and direction of realized gene flow. While hybrids are common in anthropogenic landscapes, our results suggest that even small forested landscapes serve as substantial barriers to hybrid establishment, a key consideration for butternut conservation planning, a species already exhibiting severe decline, and for other North American forest trees that hybridize with introduced congeners.