SYMP 1-2 - Genetic extinction vortex: feedbacks between species range and adaptability loss in the Anthropocene

Anthropogenic climate change and land use alterations have already driven several thousand species to extinction. An often-overlooked impact of human activities is the significant loss of intra-species genetic diversity before extinction is imminent. A smaller pool of genomic variations limits potential adaptation to new environmental changes, which in turn leads to reduced species range, creating an extinction vortex. This could lead to the quick collapse of many species before conservation attention, threatening ecosystem stability. To date, efforts incorporating genomics in biodiversity have been made in two contexts: (i) estimating the loss of genetic diversity as a function of habitat reduction – known as the mutations-area relationship (MAR) projections, and (ii) predicting future population fitness declines from the within-species genomic variation that could be potentially (mal)adaptive across climates – known as genomic offset, or genomic vulnerability. Despite both being useful, we do not yet know how these processes feedback on each other.
Here, we present an ongoing effort to characterize this genetic extinction vortex at a macro-ecological scale. We compiled an expanding geo-referenced genomic dataset that currently consists of 10,095 individuals from twenty species, spanning a geographic area from 0.03 million to 115 million km2 globally. Analogous to the species-area relationship, we found the mutations-area relationship: genetic diversity (M) increases with the area surveyed (A) following a power-law function: M = cAz. Using global land cover transformation data, we estimated that more than 10% of global genetic diversity may have already been lost. We are developing a MAR shiny web application to aid more researchers to calculate and visualize the MAR for their species of interest through an interactive platform.
To understand how genetic diversity loss caused by range reduction could induce loss in adaptability, we are building the feedback model for genetic extinction by connecting the MAR projections with genomic offset analyses. Using the multi-species genomic dataset, individuals will be “removed” from their geographical range, simulating realistic local extinction scenarios projected from the SDMs. Genomic offset analyses will then be performed on the remaining individuals after immediate range shifts under new environmental conditions. Through this iterative approach that simulates the effects of range and adaptability loss, we are bridging the macroecological models with local evolutionary processes to understand global genetic diversity loss.
Overall, we hope to provide a case study that demonstrates the importance of considering both ecological and evolutionary knowledge in conservation practice.