Genetic diversity reveals a complex evolutionary history for the white-fringed weevils (Coleoptera, Curculionidae)

The closely related Naupactini species Naupactus leucoloma, Naupactus peregrinus and Naupactus minor are collectively known as “white-fringed weevils” and, along with some other species, form a monophyletic group known as the “leucoloma group”. For the first two, parthenogenesis has been identified and males have been observed, while for N. minor, there have been no signs of sexual reproduction. All three are distributed in the Argentinean Mesopotamia, with an overlap observed in their geographical ranges. This, added to the intermediate morphology of N. minor between the other two and the absence of males, led to postulation of the hybrid origin of this species. Recently, after several decades, males have been found that could belong to N. leucoloma or N. minor. Using mitochondrial (COI) and nuclear (ITS1) DNA sequences and SNPs (obtained through dd-RAD-Seq), we aimed to survey the levels of genetic variation in the leucoloma group and unveil hybridization traces.

The three datasets yielded consistent results regarding the number of evolutionary groups, indicating that the presumed males constitute an independent evolutionary unit. Additionally, preliminary analysis with the SNAPP program suggests a close relationship to N. minor. A principal component analysis showed high levels of nuclear variability for N. leucoloma, in contrast to low mitochondrial variability, which could account for repeated hybridization events. On the other hand, N. minor presented high variation for both types of markers. Split tree analysis pointed out possible hybridization within the group. Altogether, our results suggest a complex evolutionary history within this group of neotropical weevils.