Verdon Gorge: Image credit: Robert Kovacs (CC0)
When we speak about the loss of biodiversity, we often think of the loss of different species from an ecosystem. However, when ecosystems start to lose biodiversity, often, the first thing lost is diversity within species. This is, individuals of the same species become more like one another, leading to a loss of variety within a species.
This can cause issues at the species level as a lack of variation means that the species as a whole is less able to adapt to new environmental challenges, which can potentially lead to extinction. Humans are driving a loss of biodiversity worldwide, but it is unclear how the loss of diversity within a species affects ecosystems.
To answer this question, Fargeot et al. analyzed a complete food chain in an aquatic ecosystem in the wild, quantifying species diversity and using genetic tools to quantify within-species diversity. The researchers also quantified seven ecosystem functions associated with the ecosystem's productivity (how much biomass the ecosystem produces) and its ability to degrade dead organic matter.
Fargeot et al. found that the effects of losing within-species diversity in the ecosystem were as impactful as losing species diversity. The scientists also discovered that the relative impact of within- and between-species diversity on ecosystems were opposite. Losing species surprisingly increased the rate of ecosystem function, which also increased the amount of biomass produced and the amount of degraded organic matter. Conversely, losing diversity within species slowed down these ecosystem functions and thus decreased the services they can provide to humans.
These findings imply that measuring the loss of both within-species and between-species diversity is necessary to fully understand the effects of biodiversity loss. This will inform both conservation and agricultural efforts, where within-species diversity is often ignored.
