A note on the value of genetic diversity within a species

Within the S.O.S. protocol it is noted that “each seed collection should comprise of a significant representation of the genetic variation within the sampled population.” This statement reflects a recognition, stated explicitly elsewhere in the protocol, that the capture and storage of genetic diversity within a species or within a population of a species is a goal nearly so worthwhile as the collection of seeds from a large number of species. I will use this blog post to first relate my team’s recent experience collecting seed of Juniperus osteosperma from two distinct populations and then to examine an ongoing story in which a rare, naturally occurring genotype may play a role in future ecosystem-level restoration.

My crew travelled to Washoe co., NV, on two occasions over the last week to collect cones from two stands of Juniperus osteosperma. By collecting many tens of thousands of viable seeds from a large geographic area we increased the odds of collecting genes that will allow the species to persist in an era of changing climate and novel pathogens. While it remains unknown which genes, if any, collected by my team will be of use to J. osteosperma in the future, I will offer an example of how genetic diversity may play into a future large-scale reintroduction effort in the eastern United States.

[A juniper woodland in Washoe co., NV]

Castanea dentata, the American chestnut, was driven to the edge of extinction by a fungal disease in the early 1900s. Some individuals, however, show varying degrees of genetic resistance to the pathogen. While several organizations are attempting to develop resistance to this fungal pathogen in American chestnuts by means such as the insertion of a gene found in wheat into the chestnut genome and cross-breeding with the naturally resistant C. sativa of eastern Asia, the American Chestnut Cooperators Foundation is actively cross-breeding these resistant strains of C. dentata to a degree of success. This may, in the future, allow for a reintroduction of the species into the forests of which it was once a part and a restoration of lost aspects of those forests’ ecology.

[Good job crew- that oughta do it]

While the story of C. dentata and the American Chestnut Cooperators Foundation revolves around genes that were preserved in situ in the eastern American hardwood forests, similar stories may in the future be told about a great many species which were unable to persist in their historic range under the combined stresses of habitat fragmentation, climate change, and novel pathogens and which, consequently, will revolve around the use of genetics preserved in seed banks around the world.

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