Biology subjects

Jecha, K.

Publications and source records attributed to Jecha, K..

4 recordsLinked to original sources

bioRxiv2026

Widespread but cryptic introgression shapes genetic diversity in natural populations

Introgression following hybridization is increasingly recognized as a major driver of evolution. However, its importance depends on its frequency in nature, which remains to be quantified. To address this, we provide a snapshot of ongoing introgression in a whole species assemblage (4126 ant colonies). 23% of all 82 local species show signs of introgression, which is more than twice previous estimates. Introgression is typically subtle, yet contributes measurably to genetic diversity. Species divergence, rather than classical prezygotic reproductive barriers (mating phenology, ecological niche, fine-scale habitat use) constrains introgression, suggesting that the main reproductive barriers are postzygotic at this stage of divergence. Our results indicate that introgression may be a common but often overlooked feature of natural communities.

evolutionary biology↗

bioRxiv2026

Wolbachia facilitates the reproduction of a parthenogenetic ladybug

Wolbachia is a bacterial endosymbiont that is primarily transmitted from mother to offspring. To increase their transmission, some strains manipulate their hosts reproduction to favor female offspring, such as by inducing parthenogenesis. Here, we assess whether Wolbachia induces parthenogenesis in recently discovered parthenogenetic populations of the ladybug Nephus voeltzkowi by treating females with an antibiotic. Females from sexual populations, which we show are not infected by Wolbachia, serve as a control. Our results demonstrate that the treatment decreases Wolbachia load, subsequently reducing egg production and development among parthenogenetic females, while having no effect on sexual females. Wolbachia load and reproduction then rebound when the treatment is removed. This suggests that the Wolbachia infection is necessary for successful reproduction in the parthenogenetic females, and it may play a two-part role by facilitating egg laying and late embryo development. The cooccurrence of Wolbachia infection and parthenogenesis in N. voeltzkowi, as well as Wolbachias manipulation of host reproduction makes this a likely candidate of Wolbachia-induced parthenogenesis outside of haplo-diploids. Understanding how Wolbachia can impact diverse insect reproductive systems can shed a light on the extent in which these bacteria can manipulate hosts for their own gain.

evolutionary biology↗

bioRxiv2024

Do morphologically distinct groups correspond to reproductively isolated species? A case study in Myrmica ants from Switzerland

The most widely used definition of a species is that it is reproductively isolated from other populations. Yet, most species are described on the basis of morphological criteria, and reproductive isolation is seldom tested. Using the ant genus Myrmica Latreille (Hymenoptera, Formicidae) as a model, we ask whether species described as distinct based on (often subtle) morphological differences indeed form reproductively isolated lineages. We collected and morphologically identified 918 Myrmica ants from a 3212 km2 area in Switzerland. We then combined DNA barcoding (based on COI) and RAD sequencing to identify genetically isolated lineages. Out of the 14 morphological species identified, 13 formed genetically differentiated lineages, while the last one was not supported by our genetic data. Overall, the morphological identification was congruent with genetic lineage delineation for 94.9% of individuals. Our dataset also allowed us to screen for cryptic lineages in the five most frequent species, including in M. scabrinodis where cryptic lineages were previously suggested, but we found no evidence for cryptic species. Overall, our results indicate that morphology parallels genetic isolation in the studied species. However, an integrative approach combining morphological identification with nuclear marker genotyping is necessary for confident species identification of all individuals. Finally, our results provide a library of validated COI barcodes for future Myrmica specimen identification.

evolutionary biology↗

bioRxiv2024

Decontaminating genomic data for accurate species delineation and hybrid detection in the Lasius ant genus

Advancements in genetic technologies have allowed us to generate large data sets relatively quickly and easily. However, without proper quality control checks, the inferences drawn from such data can be erroneous and go on to misinform further studies. DNA contamination between focal samples of the same or closely related species can have major impacts on downstream analyses, but their presence is seldom tested. Here, we created a pipeline combining competitive mapping to remove reads from intergeneric contamination, followed by a filtering method using allelic depth ratio frequencies to exclude intrageneric contamination. We then used a RADseq dataset of over 1,000 Swiss Lasius ants that were cross contaminated to various levels prior to sequencing to assess the impact of contamination on inferences of introgression. The original dataset presented widespread introgression between species in which hybridization has never been recorded. After thorough decontamination, we found only one individual with a strong signature of introgression, between the species L. emarginatus and L. platythorax, revealing that introgression is extremely rare in this genus. Implementing our method of filtering can significantly improve the robustness of biological findings based on genomic datasets. We recommend that systematically checking for the presence of cross contamination should be a key step in the preprocessing of genomic datasets.

genomics↗