Seed Bank Offers Clues to Climate Change, Evolution
By Gail Gallessich
In the October issue of Bioscience, Mazer, along with Steven J. Franks of Fordham University and a group of other colleagues, suggests a method of collecting and storing seeds of natural plant populations. They call it a “Resurrection Initiative,” and it involves collecting many species over time so their evolutionary responses to future climate changes can be examined.
“In contrast to existing seed banks, which exist primarily for conservation, this collection would be for research that would allow a greater understanding of evolution,” said Franks. “This seed collection would form an important resource that can be used for many types of research.”
“Wild species contain a high
degree of genetic variation
in almost any trait that
we might examine.”
– Susan J. Mazer
“Typically, seed banks are focused on the preservation of agricultural species or other plant species of strong economic interest, say, forest species, forest trees,” said Mazer. This ensures that scientists can maintain a genetically diverse seed pool in the event of some kind of ecological calamity that requires the replenishing of seeds from a certain part of the world or from certain species. “But that implies a relatively static view of a seed bank, a snapshot forever of what a species provides.”
Evolutionary biologists recognize that the gene pool of any species is a dynamic resource that changes over time as a result of random events such as highly destructive climatic events, like hurricanes, but also through sustained and ongoing processes like evolution by natural selection.
While most scientists agree that the climate is changing, the extent to which species will be able to evolve to keep up with these changes is unknown.
According to the article, the only way that scientists can detect the results of those sorts of calamitous changes — and test evolutionary predictions about what sorts of changes might occur over time –– is to sample seed banks in a repeated fashion and compare those samples to a baseline.
“Currently seed banks don’t allow this for a couple of reasons,” said Mazer. “First, they focus on species that have been under cultivation for a long period. Species that have been under cultivation have relatively low levels of genetic variation because we have been selecting them only for the attributes that we want.
“Wild species, by contrast, contain a high degree of genetic variation in almost any trait that we might examine,” she said.
Agricultural species are often selected to have a predictable flowering time, a predictable seed size –– and a predictable degree of tolerance for drought, salt, or heavy metals.
Scientists don’t know whether or not the environmental changes that are ongoing, whether due to changes in climate or land use practices, are reducing the amount of genetic variation in the wild. If they are, the only way it can be detected will be by sampling representative seeds from a larger number of populations at very regular intervals.