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Abstract

Knowledge of the manner in which genetic variation within a tree species affects
associated communities and ecosystem processes across its entire range is important for
understanding how geographic mosaics of genetic interactions might develop and support
different communities. While numerous studies have investigated the community and
ecosystem consequences of genetic variation at the hybrid cross type or genotype level within
a species, none has investigated the community-level effects of intraspecific genetic variation
across the geographic range of a widespread species. This is the scale at which geographic
mosaics of coevolution are hypothesized to exist. Studies at this level are particularly
important for foundation tree species, which typically support numerous microbial, fungal,
plant, and animal communities. We studied genetic variation across eight geographical races
of the forest tree Eucalyptus globulus representing its natural distribution across southeastern
Australia. The study was conducted in a 15-year-old common garden trial based on families
derived from single-tree open-pollinated seed collections from the wild. Neutral molecular
genetic variation within E. globulus was also assessed and compared with genetic divergence in
the phenotypic and community traits. Three major findings emerged. First, we found
significant genetically based, hierarchical variation in associated communities corresponding
to geographical races of E. globulus and families within races. Second, divergence in foliar
communities at the racial level was associated with genetically based divergence in specific leaf
morphological and chemical traits that have known defensive functions. Third, significant
positive correlations between canopy community dissimilarity and both neutral molecular
genetic and leaf quantitative genetic dissimilarity at the race level supported a genetic
similarity rule. Our results argue that genetic variation within foundation tree species has the
potential to be a significant driver of the geographical mosaics of variation typical of forest
communities, which could have important ecological and evolutionary implications.

Item Type:	Article
Authors/Creators:	Barbour, RC and O'Reilly-Wapstra, J and De Little, DW and Jordan, GJ and Steane, DA and Humphreys, JR and Bailey, JK and Whitham, TG and Potts, BM
Keywords:	Australia; common garden trial; community genetics; (co)evolution; Eucalyptus globulus; forest tree; leaf morphology; neutral molecular markers; plant–animal interactions; plant secondary chemistry; provenance trial
Journal or Publication Title:	Ecology
ISSN:	0012-9658
DOI / ID Number:	https://doi.org/10.1890/08-0951.1
Additional Information:	Orginally published 2009 by the Ecological Society of America
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