Genetic diversity in reforestation: it's Ne time now

Abstract:
Genetic diversity is increasingly important in breeding programs of both economically valuable and conservation targeted species that aim to generate resilient populations. However, the best metric, method and scale for managing genetic diversity are difficult to determine. Here I focus on tree breeding and forest management in British Columbia, Canada, where centuries of harvest and reforestation have created a mosaic of planted and natural stands across the forest landscapes. Over 60% of seed used in reforestation is now provided by breeding programs with policy setting minimum genetic diversity requirements. As breeding programs continue to advance over generations and forest landscapes continue to experience climate change, questions have arisen as to the impact of breeding and reforestation on genetic diversity at the landscape level. We use effective population size (Ne) to examine genetic diversity at three scales of forest management using genomic data for three economically important and widely planted conifers. We assess current methods for monitoring genetic diversity, compare genetic diversity in selectively improved and natural seed, and examine the shift in genetic diversity from breeding orchards to maturing stands. Using a population genetic simulation model, we aim to understand the potential impacts of reforestation policy on landscape-level Ne. Our results show that Ne is significantly lower in seed from breeding programs compared to natural stands. Once selectively improved seed is planted on the landscape, conspecific natural regeneration substantially buffers genetic diversity. Reforestation can have substantial impacts on landscape-level Ne, the magnitude of which depends heavily on the proportion of landscape harvested. These results will be used to evaluate and inform current policy and practice.

About the Speaker:
Dr. Hayley Tumas is a conservation geneticist and research associate with the University of British Columbia. She received her BS in Biology from the University of Maryland, College Park and her PhD in Forestry and Natural Resources from the Univeristy of Georgia. Her doctoral dissertation work examined the landscape and population genetics of a coastal plant species across the southeastern United States. She started work in forest genetics with Dr. John MacKay at the Univeristy of Oxford developing genomic markers and a genetic map for the UK population of Sitka spruce. She then joined Dr. Sally Aitken at UBC to examine genetic diversity in BC reforestation. The goal of her work is to apply genetic techniques to problems in conservation and managment and she has experience working across sectors with industry and government.

Contact

Jill Hamilton
jvh6349@psu.edu