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Abstract Forest trees provide critical ecosystem services for humanity that are under threat due to ongoing global change. Measuring and characterizing genetic diversity are key to understanding adaptive potential and developing strategies to mitigate negative consequences arising from climate change. In the area of forest genetic diversity, genetic divergence caused by large-scale changes at the chromosomal level has been largely understudied. In this study, we used the RNA-seq data of 20 co-occurring forest trees species from genera including Acer, Alnus, Amelanchier, Betula, Cornus, Corylus, Dirca, Fraxinus, Ostrya, Populus, Prunus, Quercus, Ribes, Tilia, and Ulmus sampled from Upper Peninsula of Michigan. These data were used to infer the origin and maintenance of gene family variation, species divergence time, as well as gene family expansion and contraction. We identified a signal of common whole genome duplication events shared by core eudicots. We also found rapid evolution, namely fast expansion or fast contraction of gene families, in plant–pathogen interaction genes amongst the studied diploid species. Finally, the results lay the foundation for further research on the genetic diversity and adaptive capacity of forest trees, which will inform forest management and conservation policies.
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Molecular Signatures of Adaptation and Selection in Forest Trees
Uncovering the genes and molecular basis of phenotypic variation and adaptation is a major goal in conservation and evolutionary genetics; it also sets the basis for future operational breeding in commercial species, like forest trees. These taxa are characterized by their large size, growth habit and longevity, which hampers the use of reverse-genetic approaches (i.e. from gene function to phenotype) to pinpoint adaptive molecular variants. In this chapter, we summarize the basis of the forward-genetic approaches (i.e. from phenotype to gene function) currently used in forest trees. For each strategy, we provide a brief overview of the statistical approaches employed to identify candidate genes, and then highlight the main findings of landmark studies that provide evidence for adaptation in forest trees. Adaptive and commercial traits are generally well inherited in trees, although they are mostly affected by the variation of multiple genes, each one accounting for a small part of the phenotypic variance of each character. However, some individual and important genes involved in growth, phenology, drought resistance and cold hardiness have been identified; many of them showing evidence of selection across multiple taxa (sometimes including angiosperms and gymnosperms). Future challenges for detecting the signatures and understanding the molecular basis of adaptation in trees include more adequate and precise phenotype assessment in natural populations, and the inclusion of gene interactions and epigenetic variations in current models. The implications of these findings in conservation and breeding of forest trees are finally discussed.
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- Award ID(s):
- 1461868
- PAR ID:
- 10210920
- Date Published:
- Journal Name:
- Advances in botanical research
- Volume:
- 74
- ISSN:
- 0065-2296
- Page Range / eLocation ID:
- 265-306
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/bs.abr.2015.04.003
