Biological features of seeds of a wild-growing species of Poterium polygamum

Relevance. Biological features (morphometric indicators, viability and germinating power) of Poterium polygamum seeds found in natural communites of the Stavropol Territory have been studied. The conservation of wild-growing plant species in the natural population and the rational use of their potential are relevant.Methods. Years of study — 2013–2021. The subject of the study is Poterium polygamum seeds. Seeds were collected in 2013. Studies were carried out according to the methods of studying seed material. Freshly harvested seeds and seeds of different shelf life were germinated in petri dishes at a temperature of 18–20 °C.Results. The collected seeds of Poterium polygamum are quite large. The length of the seeds is 4–5 mm, the width is about 2.5 mm. The mass of 1000 pieces of seeds on average was 10.59 grams. Complete absence of viability of freshly harvested Poterium polygamum seeds was revealed. After three months, seed viability was 97%. This is a shallow physiological rest associated with the post-harvest maturation period. During the storage of seeds, their high germination was established — from 70 to 100%. The duration of seed storage is 8 years. The largest number of germinated seeds and their germinating power were noted in the third year of their storage (100%). Seeds germinated on the third or fourth day. The differences between the viability of seeds and their germinating power are not great. In the eighth year of storage of Poterium polygamum seeds, viability and germinating power were slightly reduced. The storage period of seeds, in which they retain the ability to germinate and the germinating power, is long. It has been found that the wild species Poterium polygamum belongs to plants with a high (70 to 100%) viability. This species is regularly resumed in the natural population. The revealed biological features of Poterium polygamum seeds can become the scientific basis during the reconstruction of degraded natural grass stand and in selection work.

Comparative Transcriptome Analysis of Two Populations of Dastarcus helophoroides (Fairmaire) under High Temperature Stress

The differentially expressed genes (DEGs), key genes and metabolic pathways of the parasitic beetle, Dastarcus helophoroides (Fairmaire), were compared between the fiftieth commercially reared population and the first natural population to reveal the adaptive mechanism in response to high temperature stress. The high-throughput sequencing technique was employed for transcriptome sequencing of two populations of D. helophoroides. In total, 47,763 non-redundant transcripts with the average length of 989.31 bp and the N50 of 1607 bp were obtained. Under high temperature stress, 1108 DEGs were found in the commercial population; while there were 3946 DEGs in the natural population, which were higher than those in the commercial population (3.56 times). High temperature stress of D. helophoroides promoted the expression of heat shock proteins (HSPs) and metabolism-related genes in both populations, but metabolism synthesis and hydrolysis of natural population was much higher, allowing them to produce more resistant substances (such as HSPs, superoxide dismutase (SOD), peroxiredoxin (Prx), etc.). Therefore, HSPs may play a major role in the high temperature adaptation of a commercial population, while the natural population probably respond to heat stress with more resistant substances (such as HSPs, SOD, Prx, etc.). These results provide a reference to select and domesticate a specific ecotype with stronger adaptability to the high temperature weather in the forest and further improve the efficiency of D. helophoroides as a bio-control factor.

Spontaneous parthenogenesis in the parasitoid wasp Cotesia typhae: low frequency anomaly or evolving process?

Hymenopterans are haplodiploids and unlike most other Arthropods they do not possess sexual chromosomes. Sex determination typically happens via the ploidy of individuals: haploids become males and diploids become females. Arrhenotoky is believed to be the ancestral reproduction mode in Hymenopterans, with haploid males produced parthenogenetically, and diploid females produced sexually. However, a number of transitions towards thelytoky (diploid females produced parthenogenetically) have appeared in Hymenopterans, and in most cases populations or species are either totally arrhenotokous or totally thelytokous. Here we present the case of Cotesia typhae (Fernandez-Triana), a Braconidae that produces parthenogenetic females at a low frequency. The phenotyping of two laboratory strains and one natural population showed that this frequency is variable, and that this rare thelytokous phenomenon also happens in the wild. Moreover, mated females from one of the laboratory strains produce a few parthenogenetic daughters among a majority of sexual daughters. The analysis of daughters of heterozygous virgin females allowed us to show that a mechanism of automixis with central fusion is very likely at play in C. typhae. This mechanism allows some parts of the genome to remain heterozygous, especially at the chromosomes' centromeres, which can be advantageous depending on the sex determination system involved. Lastly, in most species, the origin of thelytoky is either bacterial or genetic, and an antibiotic treatment as well as PCR experiments did not demonstrate a bacterial cause in C. typhae. The unusual case of low parthenogenetic frequency described in this species constitutes another example of the fascinating diversity of sex determination systems in Arthropods.

Natural reduction of Ukraine’s population: Regional dimensions of the national threat

A significant decline in Ukraine’s population is mainly due to its natural decrease, which began in the 1970s and 1980s in the rural areas and had been determined by the objective trends in demographic transition, the inertia effect of the demographic losses in the past and the social policy of the political regime at that time. Likewise, the social and economic crisis of the 1990s deepened the depopulation processes. In the present research, correlation analysis demonstrated a relationship between the current dimensions of natural population decline and a number of socio-demographic factors (proportion of the rural population, mean age of the population, divorce rate and the mean age at first marriage). In recent years, the effects of the demographic crisis have been particularly acute in North-eastern and Central Ukraine, due to the deepening disproportions in the age and sex structures of the population. However, in the capital of Ukraine, Kyiv, and in some western regions, the natural decrease in population is less acute because of more balanced social and demographic indicators. Although religious and ethnic factors contribute to some extent to greater natural population growth, especially in the western and south-western regions, their impact on the processes of population reproduction in Ukraine is generally not significant. To sum up, in order to stop natural population decline in Ukraine, it is important to ensure more favourable conditions for demographic development in the economic, social, informational and cultural spheres of society. Furthermore, in areas of acute demographic crisis, it is important to raise the issue of rural reconstruction involving a variety of organisational and economic mechanisms.

Gut microbiome composition, not alpha diversity, is associated with survival in a natural vertebrate population

Background The vertebrate gut microbiome (GM) can vary substantially across individuals within the same natural population. Although there is evidence linking the GM to health in captive animals, very little is known about the consequences of GM variation for host fitness in the wild. Here, we explore the relationship between faecal microbiome diversity, body condition, and survival using data from the long-term study of a discrete natural population of the Seychelles warbler (Acrocephalus sechellensis) on Cousin Island. To our knowledge, this is the first time that GM differences associated with survival have been fully characterised for a natural vertebrate species, across multiple age groups and breeding seasons. Results We identified substantial variation in GM community structure among sampled individuals, which was partially explained by breeding season (5% of the variance), and host age class (up to 1% of the variance). We also identified significant differences in GM community membership between adult birds that survived, versus those that had died by the following breeding season. Individuals that died carried increased abundances of taxa that are known to be opportunistic pathogens, including several ASVs in the genus Mycobacterium. However, there was no association between GM alpha diversity (the diversity of bacterial taxa within a sample) and survival to the next breeding season, or with individual body condition. Additionally, we found no association between GM community membership and individual body condition. Conclusions These results demonstrate that components of the vertebrate GM can be associated with host fitness in the wild. However, further research is needed to establish whether changes in bacterial abundance contribute to, or are only correlated with, differential survival; this will add to our understanding of the importance of the GM in the evolution of host species living in natural populations.

Transposon Extermination Reveals Their Adaptive Fitness Contribution

Transposable Elements are molecular parasites that persist in their host genome by generating new copies to outpace natural selection. Here we measure the parameters governing the copy number dynamics of the fission yeast Tf2 retrotransposons, using experimental and natural populations and a strain where all Tf2 copies are removed. Natural population genomes display active and persistent Tf2 colonies, but in the absence of selection mitotic recombination deletes Tf2 elements at rates that far exceed transposition. We show that Tf2 elements provide a fitness contribution to their host by dynamically rewiring the transcriptional response to metabolic stress. Therefore, Tf2 elements exhibit a mutualistic rather than parasitic behavior toward their host.

Wolbachia reduces virus infection in a natural population of Drosophila

Wolbachia is a maternally transmitted bacterial symbiont that is estimated to infect approximately half of arthropod species. In the laboratory it can increase the resistance of insects to viral infection, but its effect on viruses in nature is unknown. Here we report that in a natural population of Drosophila melanogaster, individuals that are infected with Wolbachia are less likely to be infected by viruses. By characterising the virome by metagenomic sequencing and then testing individual flies for infection, we found the protective effect of Wolbachia was virus-specific, with the prevalence of infection being up to 15% greater in Wolbachia-free flies. The antiviral effects of Wolbachia may contribute to its extraordinary ecological success, and in nature the symbiont may be an important component of the antiviral defences of insects.

Identification of cold tolerance QTLs at the bud burst stage in 211 rice landraces by GWAS

Background Rice is a crop that is very sensitive to low temperature, and its morphological development and production are greatly affected by low temperature. Therefore, understanding the genetic basis of cold tolerance in rice is of great significance for mining favorable genes and cultivating excellent rice varieties. However, there have been limited studies focusing on cold tolerance at the bud burst stage; therefore, considerable attention should be given to the genetic basis of cold tolerance at this stage. Results In this study, a natural population consisting of 211 rice landraces collected from 15 provinces in China and other countries was used for the first time to evaluate cold tolerance at the bud burst stage. Population structure analysis showed that this population was divided into two groups and was rich in genetic diversity. Our evaluation results confirmed that japonica rice was more tolerant to cold at the bud burst stage than indica rice. A genome-wide association study (GWAS) was performed with the phenotypic data of 211 rice landraces and a 36,727 SNP dataset under a mixed linear model. Twelve QTLs (P < 0.0001) were identified for the seedling survival rate (SR) after treatment at 4 °C, in which there were five QTLs (qSR2–2, qSR3–1, qSR3–2, qSR3–3 and qSR9) that were colocalized with those from previous studies and seven QTLs (qSR2–1, qSR3–4, qSR3–5, qSR3–6, qSR3–7, qSR4 and qSR7) that were reported for the first time. Among these QTLs, qSR9, harboring the most significant SNP, explained the most phenotypic variation. Through bioinformatics analysis, five genes (LOC_Os09g12440, LOC_Os09g12470, LOC_Os09g12520, LOC_Os09g12580 and LOC_Os09g12720) were identified as candidates for qSR9. Conclusion This natural population consisting of 211 rice landraces combined with high-density SNPs will serve as a better choice for identifying rice QTLs/genes in the future, and the detected QTLs associated with cold tolerance at the bud burst stage in rice will be conducive to further mining favorable genes and breeding rice varieties under cold stress.

Features of depopulation in perm krai: state and trends

Objective. To study the features of depopulation in Perm Krai. Materials and methods. The data of Perm Krai official statistics for 20052019 were used; dynamics of vital rate compared to mean indicators in the Russian Federation were studied. Results. Since 2005 to 2019, the population in Perm Krai decreased by 5.7 %, whereas in the Russian Federation for the same period it grew by 2.1 % at the expense of migration processes; birth rate in Perm Krai reduced by 6.4 %; mortality rate in Perm Krai is 13.23 %. There is a growth trend of the natural population loss in both Perm Krai and the Russian Federation. Conclusions. In Perm Krai, there is observed an unfavorable demographic situation, which is characterized by a continuing decrease in the population and natural population loss. To improve the demographic situation in Perm Krai, it is expedient to develop a complex of measures directed to reduction of mortality, stimulation of birth rate, support of families with children as well as restoration of traditional family values and moral principles.