Are we ready for applying genetic diversity indicators? A cross-taxa pilot assessment of wild animal and plant populations in Bulgaria

Abstract Genetic diversity ensures species adaptive potential and prospects for long-term survival; therefore, its estimation represents an essential conservation tool. For this purpose, the Kunming–Montreal Global Biodiversity Framework under the Convention of Biological Diversity endorsed a dedicated headline indicator A.4 “The proportion of populations within species with an effective population size > 500”, hereafter Ne 500 , and a complementary indicator “the proportion of maintained populations within a species”, hereafter PM. To assess the genetic health of Bulgarian wild populations, we calculated these, using genetic or proxy data, for a set of 96 species: 36 mammals, 20 birds, 1 reptile, 2 amphibians, 5 fish, 14 invertebrates, 12 angiosperms, 5 gymnosperms, and 1 spore-bearing plant. Most of the assessed species (72%), had a favourable PM indicator value of 1, meaning they had not lost any population since the baseline year 2000. However, only 44% had a favourable value of Ne 500 =1, meaning all their populations surpassed the threshold of an effective population size of 500 individuals. This emphasizes the need to include information on genetic diversity in the national legislation and biodiversity monitoring programs, which is currently not the case. To fill this gap and facilitate the implementation of the PM and Ne 500 indicators in Bulgaria, we discuss their appropriate use in different taxonomic groups and outline our vision of future genetic research and monitoring in the country. Despite the use of local and non-exhaustive data, our insights and recommendations are useful for other countries where genetic monitoring is still in its infancy.