Trends in taxonomy of Triatomini (Hemiptera, Reduviidae, Triatominae): reproductive compatibility reinforces the synonymization of Meccus Stål, 1859 with Triatoma Laporte, 1832

Background Meccus' taxonomy has been quite complex since the first species of this genus was described by Burmeister in 1835 as Conorhinus phyllosoma. In 1859 the species was transferred to the genus Meccus and in 1930 to Triatoma. However, in the twentieth century, the Meccus genus was revalidated (alteration corroborated by molecular studies) and, in the twenty-first century, through a comprehensive study including more sophisticated phylogenetic reconstruction methods, Meccus was again synonymous with Triatoma. Events of natural hybridization with production of fertile offspring have already been reported among sympatric species of the T. phyllosoma subcomplex, and experimental crosses demonstrated reproductive viability among practically all species of the T. phyllosoma subcomplex that were considered as belonging to the genus Meccus, as well as between these species and species of Triatoma. Based on the above, we carried out experimental crosses between T. longipennis (considered M. longipennis in some literature) and T. mopan (always considered as belonging to Triatoma) to evaluate the reproductive compatibility between species of the T. phyllosoma complex. In addition, we have grouped our results with information from the literature regarding crosses between species that were grouped in the genus Meccus with Triatoma, in order to discuss the importance of experimental crosses to confirm the generic reorganization of species. Results The crosses between T. mopan female and T. longipennis male resulted in viable offspring. The hatching of hybrids, even if only in one direction and/or at low frequency, demonstrates reproductive compatibility and homeology between the genomes of the parents. Conclusion Considering that intergeneric crosses usually do not result in viable offspring in Triatominae, the reproductive compatibility observed between the T. phyllosoma subcomplex species considered in the Meccus genus with species of the Triatoma genus shows that there is “intergeneric” genomic compatibility, which corroborates the generic reorganization of Meccus in Triatoma. Graphic Abstract

Reproductive compatibility of Sorbocotoneaster with mountain ash species and varieties that are promising for breeding in Siberia

In Russia, in the Republic of Yakutia, there is the only point in the world where natural intergeneric hybridization of species of the genera Sorbus and Cotoneaster is observed, resulting in the formation of a new hybridogenic genus ×Sorbocotoneaster with a rich polymorphism of parental genera traits. For the selection of mountain ash in Siberia, it is promising to involve Sorbocotoneaster genotypes in artificial hybridization as sources of a complex of economically valuable traits, including winter hardiness, short stature, and self-fertility. Artificial hybridization of the tetraploid selective form Sorbocotoneaster with selected forms and varieties of Sorbus sibirica, S. aucuparia, S. sambucifolia and their hybrids allows obtaining viable hybrid offspring in combinations where Sorbocotoneaster is used as a pollen donor.

Cross-mating between Chinese population of Neoseiulus californicus (Acari: Phytoseiidae) and that from the commercial one from USA

Based on morphological and molecular characters, a Neoseiulus species collected from southern China was identified as Neoseiulus californicus (McGregor), which was not recorded in China before 2012. However, the Chinese population of N. californicus has some unique biological features and its morphology is also somewhat different from those populations from outside China. In order to clarify if there was reproductive isolation or reduction in the reproductive rates between Chinese population and the commercial population of N. californicus (originated from California, USA), reproductive compatibility between the specimens of two different populations was evaluated under laboratory conditions to ascertain their conspecificity. Inter-population crosses showed there was no reproductive isolation between the Chinese population and the commercial population. The results confirmed that these two belong to the same species, in agreement with the results based on morphological and molecular identifications of the Chinese N. californicus.

Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa

Wolbachia, intracellular endosymbionts, are estimated to infect about half of all arthropod species. These bacteria manipulate their hosts in various ways for their maximum benefits. The rising global temperature may accelerate species migration and, thus, horizontal transfer of Wolbachia may occur across species previously not in contact. We transinfected and then cured the alpine fly Drosophila nigrosparsa with Wolbachia strain wMel to study its effects on this species. We found low Wolbachia titer, possibly cytoplasmic incompatibility, and an increase in locomotion of both infected larvae and adults compared with cured ones. However, no change in fecundity, no impact on heat and cold tolerance, and no change in wing morphology were observed. Although Wolbachia increased locomotor activities in this species, we conclude that D. nigrosparsa may not benefit from the infection. Still, D. nigrosparsa can serve as a host for Wolbachia because vertical transmission is possible but may not be as high as in the native host of wMel, Drosophila melanogaster.

Ancestral Admixture Is the Main Determinant of Global Biodiversity in Fission Yeast

Mutation and recombination are key evolutionary processes governing phenotypic variation and reproductive isolation. We here demonstrate that biodiversity within all globally known strains of Schizosaccharomyces pombe arose through admixture between two divergent ancestral lineages. Initial hybridization was inferred to have occurred ∼20–60 sexual outcrossing generations ago consistent with recent, human-induced migration at the onset of intensified transcontinental trade. Species-wide heritable phenotypic variation was explained near-exclusively by strain-specific arrangements of alternating ancestry components with evidence for transgressive segregation. Reproductive compatibility between strains was likewise predicted by the degree of shared ancestry. To assess the genetic determinants of ancestry block distribution across the genome, we characterized the type, frequency, and position of structural genomic variation using nanopore and single-molecule real-time sequencing. Despite being associated with double-strand break initiation points, over 800 segregating structural variants exerted overall little influence on the introgression landscape or on reproductive compatibility between strains. In contrast, we found strong ancestry disequilibrium consistent with negative epistatic selection shaping genomic ancestry combinations during the course of hybridization. This study provides a detailed, experimentally tractable example that genomes of natural populations are mosaics reflecting different evolutionary histories. Exploiting genome-wide heterogeneity in the history of ancestral recombination and lineage-specific mutations sheds new light on the population history of S. pombe and highlights the importance of hybridization as a creative force in generating biodiversity.