Many populations too small to sustain genetic diversity
A new global study shows that more than half of the studied populations are too small to maintain enough genetic diversity to safeguard adaptive capacity. Genetic indicators for 919 species, representing more than 5 000 populations, have been assessed.
Photo: Magnus Renmyr/Mostphotos
Genetic diversity – variation in the DNA code among individuals of the same species – helps species and ecosystems to adapt and survive. If we think about global warming, corals need to be able to survive in warmer water, plants are exposed to rising oceans, and birds and other animals experience new diseases. Genetic diversity is the biological characteristic where the solution to some of these problems lays. But are we saving enough genetic diversity?
In December 2022, 196 countries signed an agreement, the Kunming-Montreal Global Biodiversity Framework (GBF), to halt biodiversity loss by 2030. Among the commitments was an unprecedented milestone: conserving genetic diversity and monitoring and reporting its status for all species, not just those of socio-economic and cultural value. This significant advancement aims to protect the very foundation of biodiversity, but it brings new challenges. Can we monitor genetic diversity at scale, affordably, everywhere considering that genetic studies are expensive and require fancy labs, and lack enough personnel?
Genetic diversity can be monitored
An international team of 49 researchers has been working to answer this question and their results are published in the scientific journal Ecology Letters. The answer is a clear “Yes we can.” It is feasible and necessary to estimate and monitor genetic diversity at a multiscale: national and global. The way to do it is by using either genetic or ecological survey data that come from available sources such as Red List information, species observation data, published scientific studies, action plans, citizenscience databases, etc.
Photo: Sören Andersson
“We find that populations are typically too small to maintain enough genetic diversity to safeguard adaptive capacity, says Linda Laikre, who led the Swedish team of the study. 58 percent of the assessed populations are below the threshold value set by the new monitoring framework of the Kunming-Montreal GBF.”
First attempt to assess genetic diversity at country level
The research was led by Alicia Mastretta-Yanes, from the National University of Mexico, and Jessica da Silva, from the South African National Biodiversity Institute. In total, nine countries from all continents contributed with assessments, including Sweden. Together, the researchers undertook the first attempt to assess genetic diversity at a country level using rapid, affordable and inclusive metrics.
DNA laboratories not necessary
The study demonstrated that it is feasible to monitor genetic diversity through applying two genetic diversity indicators that were adopted in the GBF, one as headline A.4 (mandatory to report on) and another as complementary indicator (optional). The headline indicator monitors if populations are large enough to sustain genetic diversity, and the component indicator monitors if populations (and thus the genetic diversity between them) are maintained. Interestingly, by focusing on population size and the existence of populations, these indicators provide a “shortcut” or “proxy” to DNA-based monitoring. This means that they do not necessarily require DNA laboratories and equipment but rather use available survey data on population size and occurrence. This makes them accessible to a wide range of countries with varying resources.
In total the authors analyzed genetic indicators for 919 species, representing more than 5 000 populations. The findings were revealing: while the majority of analyzed species maintain most of their populations, 58 percent of them have populations that are too small to sustain genetic diversity. Furthermore, the results indicate that the globally accepted “gold standard” conservation assessment, such as the IUCN Red List, do not adequately represent genetic status, highlighting the critical importance of monitoring genetic diversity as well in their assessments.
120 Swedish populations of species assessed
“The pattern is the same in Sweden. We have assessed populations of 120 species including all amphipians and reptiles and find that only 46 percent of amphibian populations are sufficently large. In contrast, populations are so far largely maintained over time which is encouraging,” says Linda Laikre.
The Swedish assessments of these proxy-based indicatores have been linked to ongoing efforts using DNA-based techniques and are supported by the Swedish Environmental Protection Agency and the Swedish Agency for Marine and Water Management. Artdatabanken (SLU Swedish Species Information Centre) has also participated in the Swedish work.
According to the study, monitoring genetic diversity with the indicators adopted at the GBF, nations can respond to the urgent need of tracking and conservation of the genetic diversity of their biodiversity. This will also contribute significantly to the global effort to monitor and preserve our planet’s nature and its capacity to adapt to climate change.
Last updated: July 3, 2024
Source: Communications Office