Conservation Genetics of the Endangered Danube Clouded Yellow Butterfly Colias myrmidone (Esper, 1780) in the Last Central European Stronghold: Diversity, Wolbachia Infection and Balkan Connections.

Abstract

The Danube Clouded Yellow (Colias myrmidone) has experienced one of the most dramatic declines among European butterflies. To estimate genetic diversity in the last population in Poland that has survived in the Knyszyn Forest (KF), we analyzed mitochondrial (COI) and nuclear (EF-1α) polymorphisms in individuals sampled in 2014 and 2022. The results were compared with genetic data obtained in 2014 from a recently extirpated nearby population (Czerwony Bór, CB). Because mtDNA polymorphisms in insects can be modulated by endosymbionts, the samples were screened for Wolbachia. The polymorphism of EF-1α indicated that diversity was gradually decreasing. The KF experienced rapid demographic processes, manifested by a significant change in allele frequency. The small differentiation in nuclear markers between the KF and CB in 2014 suggests that the regional population used to be genetically uniform. Four COI haplotypes that were identified in this study probably belong to two different haplogroups. Wolbachia was detected only in individuals with one specific haplotype, and the prevalence was female-biased, suggesting the induction of two reproductive manipulations. The most common COI haplotype found in Poland was the same as that reported from other parts of Europe, not only for C. myrmidone but also C. caucasica. These results allow us to question the distinctiveness of each taxa.