Many of the benefits that people get from nature depend on the diversity within species, but this difference between species is poorly understood and is rapidly declining
The rapid loss of diversity within species is a subtle biodiversity crisis, according to the authors of a new study looking at how this difference supports the basic ecological functions and benefits that nature provides to people.
Posted on March 1 on Nature’s ecology and evolutionThe study highlights the need to better understand and preserve differences within species in order to protect nature’s contributions to people.
“Biodiversity means more than the number of species, and when we focus on species-level extinctions, we are missing part of the story,” said corresponding author Eric Palkovac, professor of ecology and evolutionary biology at the University of California, Santa Cruz. “Indeterminate variability is a neglected aspect of biodiversity, but it is of value to people, and we need to start recognizing that and protecting this form of biodiversity.”
A previous study led by first author Simone Des Roches, a postdoctoral researcher at the University of California, Santa Cruz now at the University of Washington, showed that a loss of variation within species can have serious environmental consequences. This prompted de Rochis and Balcovac to think about the broader implications of their findings for the values and services that nature provides to people, from forest materials and clean water to commercial fisheries and medicines derived from natural products.
For the new study, they scanned the scientific literature for studies showing how nonspecific variation supports ecosystem services and other aspects of nature’s contributions to people. They find well-documented links across a wide range of species, including fish, commercial fisheries, insects, pollination of crops, woody plants, forest products, many different crops and their wild ancestors, and more.
“There is a whole bunch of documented cases, including many examples of what happens when we lose the variation within the determinant,” Balkovac said. “One of the best examples is commercial fisheries, where diversified fish stocks help stabilize the population at large.”
Salmon subpopulations, for example, are locally adapted to different watershed conditions, allowing the population to remain stable even with environmental fluctuations that cause a decrease in some subpopulations and an increase in others. These “preservative effects” in salmon are undermined by dams, which prevent subpopulations from critical spawning habitats, and hatchery production, and which can reduce genetic variability. Loss of nonspecific variability in salmon can lead to boom and bust cycles that damage the value of the fisheries in the long term.
De Roch noted that people have long relied on variation within domesticated and agricultural species. “Our history of co-evolution with hundreds of domesticated species is characterized by our constant selection of unusual and beneficial variables within species,” she said. “We often took this too far, and thus lost important genetic diversity in domesticated species. We depend on interbreeding with more genetically diverse wild species or ancestral groups (when present) to restore this diversity.”
Palkovacs said plants with medicinal value provide other well-documented examples of the value of variation within a determinant. “Different species of the same plant species may contain different compounds with different medicinal properties, such as different anti-malarial drugs that depend on the genetic diversity of the plants derived from them.”
The authors emphasized the importance of collaborating with local and indigenous groups who have a deep knowledge of the relationships between indeterminate variation and the natural products and services they use. “We need to leverage local knowledge systems to enrich our understanding of these links,” Balkovacs said.
He noted that Western science has focused heavily on species-level extinctions, and only the most well-studied groups of organisms have been distinguished from the point of view of intra-species variation. Of all the species that have been evaluated by the International Union for Conservation of Nature (IUCN), for example, only about 1 percent have been evaluated below the species standard, and many of them show a steep decline in diversity.
“There is strong evidence that the loss of indeterminate variance may be a very widespread problem, but we don’t even know what it has lost,” Balkovac said.
He said that practical steps could be taken now to better document that disparity, preserve biodiversity and protect its contributions to the well-being of people. New genomic tools are available, for example, to rapidly and systematically characterize intra-species variability. This non-specific difference can be directly incorporated into biodiversity assessments, such as those conducted by the International Union for Conservation of Nature and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).
The authors said that addressing this aspect of biodiversity should be a major goal of global conservation efforts. “The available evidence strongly suggests that the benefits of studying and maintaining variance within the determinant will far outweigh the costs,” Balkovac said.
He noted that intra-species variation is the raw material for adaptive evolution. In a rapidly changing world, this difference is extremely important to enable the species to adapt to conditions of an unexpected future.
In addition to Palkovacs and Des Roches, co-authors of the environmental economist paper include Linwood Pendleton, Senior Vice President of Science at the Center for the Fourth Industrial Revolution, and Beth Shapiro, professor of ecology and evolutionary biology at the University of California, Santa Cruz and Howard. Investigator Hughes Medical Institute. This work was supported by the University of California and NOAA.