Biological Features and Molecular Genetic Structure of Habrobracon hebetor Populations

One of the promising entomophages capable of controlling the abundance of the codling moth is Habrobracon hebetor Say. Natural populations of the gabrobragon can reduce the number of caterpillars of the corn moth to 22%, the garden moth to 35%, the cotton moth to 45%, and the gamma moth to 30%. This work aims to assess the parasitic activity of the gabrobragon as a regulator of the codling moth abundance in various geographic populations, to select a host insect for its mass breeding in laboratory conditions, and to assess the molecular genetic variability of the structure of H. hebetor populations. The capture of natural populations of the gabrobragon H. hebetor was carried out in apple orchards in Krasnodar Krai and Stavropol Krai of Russia using cassettes in which caterpillars of the codling moth were placed. As a result of the research, the natural starting population of the gabrobragon H. hebetor was captured, and a method for their maintenance and breeding was developed. The most effective host insect is the wax moth (Galleria mellonela L.), which resulted in 195 adults, compared to 98 of the mill moth (Ephestia kuhniella Zell.). The gabrobragon population introduced into the apple tree cenosis continued its reproduction in natural conditions and largely suppressed the number and harmfulness of the codling moth. The RAPD analysis of the Krasnodar and Stavropol populations of Habrobracon hebetor Say revealed a high level of DNA polymorphism and genetic diversity in the studied geographic populations of the gabrobragon. At the same time, intrapopulation variability was 87.1%, while interpopulation variability accounted for 12.9% of the total indicator. The limited gene flow (Nm = 3.298) results in relatively low identity (GI = 0.906) between populations and significant interpopulation variability. This indicates that the analyzed insect samples probably represent different geographic populations of the H. hebetor ectoparasite.

First insight of genetic diversity, phylogeographic relationships and population structure of marine sponge Chondrosia reniformis from the eastern and western Mediterranean coasts of Tunisia

The cytochrome oxidase subunit I (COI) gene was amplified and analyzed for 70 Mediterranean Chondrosia reniformis, collected from eight localities in Tunisia. Polymorphism results revealed high values of haplotype diversity (Hd) and very low nucleotide diversity (π). Thus, these results suggest that our sponge populations of C. reniformis may have undergone a bottleneck followed by rapid demographic expansion. This suggestion is strongly confirmed by the results of neutrality tests and “mismatch distribution”. The important number of haplotypes between localities and the high genetic differentiation (Fst ranged from 0.590 to 0.788) of the current C. reniformis populations could be maintained by the limited gene flow Nm (0.10 - 0.18). Both haplotype Network and the biogeographic analysis showed a structured distribution according to the geographic origin. C. reniformis populations are subdivided into two major clades: Western and Eastern Mediterranean. This pattern seems to be associated with the well-known discontinuous biogeographic area: the Siculo-Tunisian Strait, which separates two water bodies circulating with different hydrological, physical, and chemical characteristics. The short dispersal of pelagic larvae of C. reniformis and the marine bio-geographic barrier created high differentiation among populations. Additionally, it is noteworthy to mention that the “Mahres / Kerkennah” group diverged from Eastern groups in a single sub-clade. This result was expected, the region Mahres / Kerkennah, presented a particular marine environment.

Spatially explicit paleogenomic simulations support cohabitation with limited admixture between Bronze Age Central European populations

The Bronze Age is a complex period of social, cultural and economic changes. Recent paleogenomic studies have documented a large and rapid genetic change in early Bronze Age populations from Central Europe. However, the detailed demographic and genetic processes involved in this change are still debated. Here we have used spatially explicit simulations of genomic components to better characterize the demographic and migratory conditions that may have led to this change. We investigated various scenarios representing the expansion of pastoralists from the Pontic steppe, potentially linked to the Yamnaya cultural complex, and their interactions with local populations in Central Europe, considering various eco-evolutionary factors, such as population admixture, competition and long-distance dispersal. Our results do not support direct competition but rather the cohabitation of pastoralists and farmers in Central Europe, with limited gene flow between populations. They also suggest occasional long-distance migrations accompanying the expansion of pastoralists and a demographic decline in both populations following their initial contact. These results link recent archaeological and paleogenomic observations and move further the debate of genomic changes during the early Bronze Age.

Modern Siberian dog ancestry was shaped by several thousand years of Eurasian-wide trade and human dispersal

Dogs have been essential to life in the Siberian Arctic for over 9,500 y, and this tight link between people and dogs continues in Siberian communities. Although Arctic Siberian groups such as the Nenets received limited gene flow from neighboring groups, archaeological evidence suggests that metallurgy and new subsistence strategies emerged in Northwest Siberia around 2,000 y ago. It is unclear if the Siberian Arctic dog population was as continuous as the people of the region or if instead admixture occurred, possibly in relation to the influx of material culture from other parts of Eurasia. To address this question, we sequenced and analyzed the genomes of 20 ancient and historical Siberian and Eurasian Steppe dogs. Our analyses indicate that while Siberian dogs were genetically homogenous between 9,500 to 7,000 y ago, later introduction of dogs from the Eurasian Steppe and Europe led to substantial admixture. This is clearly the case in the Iamal-Nenets region (Northwestern Siberia) where dogs from the Iron Age period (∼2,000 y ago) possess substantially less ancestry related to European and Steppe dogs than dogs from the medieval period (∼1,000 y ago). Combined with findings of nonlocal materials recovered from these archaeological sites, including glass beads and metal items, these results indicate that Northwest Siberian communities were connected to a larger trade network through which they acquired genetically distinctive dogs from other regions. These exchanges were part of a series of major societal changes, including the rise of large-scale reindeer pastoralism ∼800 y ago.

Genetic variation of Anisoptera costata Korth in Tan Phu tropical forest, Dinh Quan district, Dong Nai province

Anisoptera costata Korth, an endangered species is distributed in lowland tropical forests of southern Vietnam. Habitat loss and over-exploitation are the major reasons for threatening this species. Eight polymorphic microsatellite markers were used to analyze 64 adult trees from three A. costata populations in lowland tropical forests of Tan Phu, Dinh Quan district, Dong Nai Province in Southeast Vietnam to detect the effects of deforestation on gene flow and the differentiation among populations in lowland tropical forests. The results showed that all A. costata populations have the moderate levels of the genetic diversity within populations with mean values of observed and expected heterozygosities, 0.242 and 0.269, respectively, moderate genetic differentiation among A. costata populations (0.179), and indicating limited gene flow (Nm = 1.15). Analysis of molecular variance indicated high genetic variation within populations (64.68%) and indicating moderate genetic structure in A. costata in Tan Phu. Bayesian analysis detected two genetic lineages, cluster 1 including one population of Mieu Co Nam and cluster 2 including two populations, Thac Mai and Bau Nuoc. These results contribute understanding genetic diversity of A. costata in lowland forests of Southeastern Vietnam and will provide guidelines for conservation, management and resoration of the species.

Honey Bee Diversity Is Swayed by Migratory Beekeeping and Trade Despite Conservation Practices: Genetic Evidences for the Impact of Anthropogenic Factors on Population Structure

The intense admixture of honey bee (Apis mellifera L.) populations at a global scale is mostly attributed to the widespread migratory beekeeping practices and replacement of queens and colonies with non-native races or hybrids of different subspecies. These practices are also common in Anatolia and Thrace, but their influence on the genetic make-up of the five native subspecies of honey bees has not been explored. Here, we present an analysis of 30 microsatellite markers from honey bees from six different regions in Anatolia and Thrace (N = 250 samples), with the aim of comparing the impact of: (1) migratory beekeeping, (2) queen and colony trade, and (3) conservation efforts on the genetic structure of native populations. Populations exposed to migratory beekeeping showed less allegiance than stationary ones. We found genetic evidence for migratory colonies, acting as a hybrid zone mobile in space and time, becoming vectors of otherwise local gene combinations. The effect of honey bee trade leaves very high introgression levels in native honey bees. Despite their narrow geographic range, introgression occurs mainly with the highly commercial Caucasian bees. We also measured the direction and magnitude of gene flow associated with bee trade. A comparison between regions that are open and those closed to migratory beekeeping allowed the evaluation of conservation sites as centers with limited gene flow and demonstrated the importance of establishing such isolated regions. Despite evidence of gene flow, our findings confirm high levels of geographically structured genetic diversity in four subspecies of honey bees in Turkey and emphasize the need to develop policies to maintain this diversity. Our overall results are of interest to the wider scientific community studying anthropogenic effects on the population diversity of honey bees and other insects. Our findings on the effects of migratory beekeeping, replacement of queens and colonies have implications for the conservation of honey bees, other pollinators, and invertebrates, in general, and are informative for policy-makers and other stakeholders in Europe and beyond.

Distribution, Genetic Diversity and Population Structure of Aegilops tauschii Coss. in Major Wheat-Growing Regions in China

Aegilops tauschii Coss. is known as a noxious grass weed seriously affecting wheat quality and yield. To investigate its present occurrence in wheat fields and the potential genetic diversity of the grass weed in China, a filed survey covering major wheat production regions was conducted during 2017–2019. Seeds of different Ae. tauschii populations collected from the survey were analyzed with Simple Sequence Repeats (SSRs) technique. Results showed that Ae. tauschii was occurring in each of the provinces surveyed with varied occurrence frequency ranging from 0.91% in Sichuan Province to 92.85% in Henan Provinces. Eighty alleles with size ranging from 98 bp to 277 bp were detected from the 192 collected Ae. tauschii populations with 17 SSR markers. Ae. tauschii, in this study, exhibited a moderately high level of genetic diversity, high differentiation, deficient heterozygosity and limited gene flow. Compared with other provinces, Hubei populations possessed relatively low genetic diversity. Dendrogram analysis showed that genetic distance did not seem to be related to geographic distribution. Additionally, STRUCTURE analysis suggested that Ae. tauschii populations in wheat fields of China can be divided into three groups, which was further supported by cluster analysis. Among the three groups, solely 7% of the total variation was detected, whereas the majority variation (67%) occurred among different populations within same group. Undoubtedly, such information will help us to better understand population relationships and spread of Ae. tauschii in China and will provide a new perspective for its integrated management.

Increases in Genetic Diversity of Weedy Rice Associated with Ambient Temperatures and Limited Gene Flow

Hypotheses regarding the association of increased species or genetic diversity with gradually warmer regions as a global pattern have been proposed, but no direct and solid experimental data are available to approve the association between plant genetic diversity and ambient temperatures. To test the diversity-temperature hypothesis, we studied genetic diversity and genetic differentiation of weedy rice (Oryza sativa f. spontanea) populations occurring naturally in early- and late-season rice fields that share nearly the same ecological conditions but with slightly different temperatures. Data collected from 10-year historical climatic records indicated a ~2 °C higher average air temperature in the late rice-cultivation seasons than in the early seasons. Results based on molecular fingerprints of 27 SSR (simple sequence repeat) loci showed a higher level of genetic diversity in the late-season weedy rice populations than in the early-season populations. In addition, a positive correlation was detected between the increased proportion of genetic diversity (ΔHe) and genetic differentiation among the weedy rice populations, suggesting limited gene flow. Therefore, we conclude from this study that increased genetic diversity in the late-season weedy rice populations is probably caused by the higher ambient temperatures. This finding provides evidence for the possible association between genetic diversity and ambient temperatures.