Investigating the origin of parthenogenesis and ploidy level in Dahlica fennicella (Lepidoptera: Psychidae)

The theories for the predominance of sexual reproduction predict that parthenogens should have no long-term evolutionary potential due to the lack of genetic recombination, despite short term advantages. Although parthenogenesis is rare among high order animals, true parthenogens can be found in various taxa. The intriguing question of the proliferation and persistence of parthenogenetic species needs investigation. An ideal species for such research is a parthenogenetic moth Dahlica fennicella that appears to be as equally successful as other coexisting sexual species. We investigated whether high ploidy level of D. fennicella is due to hybridization between closely related sexual species. The results from flow cytometry measurements confirmed that D. fennicella is exclusively tetraploid whereas all sexual species of the genera Dahlica and Siederia are diploid. Our phylogenetic results showed the non-hybrid origin of the parthenogenetic D. fennicella in this group of Lepidoptera. Most likely, the parthenogenetic D. fennicella originated by autopolyploidization of D. lazuri, which is one of its closely related sexual species. We suggest that the apparent evolutionary success of D. fennicella might be due to polyploidy that could mask deleterious mutations and provide greater levels of genetic variation.