Many mountain areas have an above -average biodiversity. Due to climate change and changed land use, however, this diversity disappears increasingly. At the same time, more shrubs and trees grow in mountainous grassland areas. The denser this vegetation has become in the past 40 years, the stronger the genetic diversity of the plants has decreased, as researchers have now found out.
Since there are many different ecosystems in mountain areas in small space, they are home to many different, sometimes specially adapted animal and plant species. In the grassland in mountain regions, herbaceous, small plants such as the Greek mountain tea (Sideritis Scardica) are growing, which occurs in the Mediterranean from a height of 1000 meters. In the course of climate change and by changing land use, however, shrubs and trees in the grassland of mountain regions are increasingly growing. Researchers then speak of so -called “greening”. In addition, the mountain tea is collected in some regions because it should help with colds and digestive problems. Its stock therefore decreases.
Old and new plants in comparison
But how does that affect the gene pool of the herbaceous plants growing there? Researchers around Spyros Theodoridis from Senckenberg have now analyzed biodiversity and climate research center in Frankfurt for the Greek mountain tea. To do this, they sequenced the genomes of 62 individuals of four mountain tea species from Herbaria, which mostly grew between 1970 and 1980 on the southern Balkans Peninsula. At that time, the effects of climate change and changed land use were not that big. In addition, they sequenced 62 genome of modern mountain tea plants that grew in the same places as the historical samples. The researchers then compared the genomes of the old and new mountain tea plants.
The comparison reveals: Most mountain tea populations are now affected by inbreeding. “In eight out of eleven mountain regions examined, the genetic diversity decreased significantly during this period,” explains Theodoridis. “In particularly affected regions, up to 20 percent of the genome of individual plants are affected by inbreeding – an indication of declining population sizes.” On average, six percent of the genome of mountain tea plants were affected by Inzucht. If the population size decreases, the gene pool of the species is reduced and inbreeding is inbreeding, the team explains. This is dangerous, since inbreeding reduces the adaptability of the plants to environmental changes and increases the risk of diseases or extinction of the population.
Denser vegetation, more inbreeding?
Using satellite images, the team led by Theodoridis also evaluated how strongly the greening in the examined areas has increased in the past 40 years. The analysis showed that over 75 percent of the areas examined are affected by strong greening on the southern Balkan Peninsula. In Central Greece, this even applies to almost 97 percent of the areas. “The speed at which bushes and trees spread in formerly open grass landscapes can be linked directly to the decline in genetic diversity in sideritis populations,” explains co-author David Nogués-Bravo from the University of Copenhagen. Thanks to this now proven connection, genetic changes in plant populations could be predicted using easily accessible satellite images. In this way, endangered populations could be recognized earlier and better protected.
Source: Senckenberg Society for Natural Research; Specialist articles: Current Biology, DOI: 10.1016/J.CUB.2025.04.007