Genetic diversity loss in the Anthropocene

Abstract

More species than ever before are at risk of extinction due to anthropogenic habitat loss and climate change. But even species that are not threatened have seen reductions in their populations and geographic ranges, likely impacting their genetic diversity. Although preserving genetic diversity is a key conservation target to maintain the adaptability of species, we lack predictive tools and global estimates of genetic diversity loss across ecosystems. By bridging biodiversity and population genetics theories, we introduce the first mathematical framework to understand the loss of naturally occurring DNA mutations within a species--what we call genetic diversity extinction. Analyzing genome-wide variation data of 10,126 geo-tagged individuals from 19 plant and animal species, we show that genome-wide diversity follows a power law with geographic area, which can predict genetic diversity decay in simulated spatial extinctions. Given pre-21st century values of ecosystem transformations, we estimate that over 10% of genetic diversity may be extinct, already surpassing the United Nations targets for genetic preservation. These estimated losses could rapidly increase with advancing climate change and habitat destruction, highlighting the need for new forecasting tools that assist in the rapid implementation of policies to protect genetic resources.

Genomic erosion in the assessment of species extinction risk and recovery potential

“…Such comparative approaches can be based on species-area relationship (SAR), citizen science databases 72 , and Species Distribution Models 73,74,75 . These analyses can be extended by fitting species abundances to the distribution of their mutation frequencies to predict rates of genetic diversity loss as a function of the species range dynamics (Mutations-Area Relationships, MAR 76 ).…”

Practical application of indicators for genetic diversity in CBD post-2020 Global Biodiversity Framework implementation

“…Still, genetic indicators require demonstration of their applicability, as they have not been used as much as species and ecosystem indicators, such as the Red List Index. The main difference between the genetic indicators and the Red List is a focus on different levels-while the Red List mainly focuses on the species level and avoiding species’ extinction, the genetic indicators are intended to look at a population level - genetic variation within and among populations and thus avoiding genetic extinction (Exposito-Alonso et al 2021). The two perspectives are also derived from population ecology and evolutionary ecology, respectively, and are thus driven by different mechanisms, where species or populations may erode genetically before population effects can be seen (Kardos and Luikart 2021; Spielman et al 2004).…”

“…Depleted species are Red Listed as LC since their populations are stable for the last three generations if their population exceeds 2000 individuals, even though their population, for example, may only have 1% left. If those populations are investigated using a genetic indicator, the longer time span enables us to identify species that may be at risk, as genetic erosion may have happened (Exposito-Alonso et al 2021) and inbreeding in isolated populations may be a threat. However, there are a few more criteria in the Red-List and combinations of criteria that may lead to species being classified as NT or more threatened even if population size is >2000.…”

Monitoring status and trends in genetic diversity for the Convention on Biological Diversity: an ongoing assessment of genetic indicators in nine countries

“…This allows evaluating whether an area is capable of housing a population Nc larger than the threshold; if the area is smaller, the Ne will likely be smaller than 500 43 . For indicator 2, if information on the number of historic populations is not known, the assessor may record overall decline in area (which is more common), which will ultimately result in lost populations and genetic diversity 7 .…”