I. A. Kozeretska

Are Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl. Migratory relicts

It remains unclear why there are only two vascular plant species in Antarctica, Deschampsia antarctica Desv. (Poaceae) and Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae). Despite progressing climate warming, there is also just one alien plant species found in the region, introduced by humans and spreading mainly in disturbed habitats. In the present article, we try to interpret the data concerning the history of the biota and glaciations of the continent, proceeding from the assumption that both plants migrated to Antarctica during the Oligocene-Pliocene, when it was less isolated and the climate was more favorable for their naturalization. Genetic evidence was also taken into consideration. Our data allow the suggestion of secondary dispersal in the region, due to transference by birds with regard to climate changes. With this in mind, we believe that D. antarctica and C. quitensis are migratory relicts.

Antarctic bdelloid rotifers: diversity, endemism and evolution

Antarctica is an isolated continent whose conditions challenge the survival of living organisms. High levels of endemism are now known in many Antarctic organisms, including algae, tardigrades, nematodes and microarthropods. Bdelloid rotifers are a key, widespread and abundant group of Antarctic microscopic invertebrates. However, their diversity, regional distribution and endemism have received little attention until recently. We provide the first authoritative review on Antarctic Bdelloidea, based on published data and new collections. Our analysis reveals the extreme levels of bdelloid endemism in Antarctica. Sixty-six bdelloid morphospecies are now confirmed from the continent, and 83–91 putative species are identified using molecular approaches (depending on the delimitation method used). Twelve previously unknown species are described based on both morphology and molecular analyses. Molecular analyses indicate that only two putative species found in Antarctica proved to be truly cosmopolitan. The level of endemism based on the available data set (95%) is higher than that in any other continent, with many bdelloid species occurring only in maritime or continental Antarctica. These findings are consistent with the long-term presence of Bdelloidea in Antarctica, with their considerable isolation facilitating intraregional radiation, providing further evidence that does not support the microbial global ubiquity hypothesis that “everything is everywhere.”

Reciprocal cross differences in Drosophila melanogaster longevity: an evidence for non-genomic effects in heterosis phenomenon?

Reciprocal cross effects (i.e., differences between reciprocal hybrids that are developed by reversing the strains from which the dam and the sire are taken) are commonly used as a measure of sex-linkage or maternal effects. However, the papers reporting parental effects on life span of experimental animals are scarce. In order to investigate the potential of parent-of-origin effects for the longevity of hybrids, we determined the life spans of the inbred lines of Drosophila melanogaster [Oregon-R (OR), Canton-S (CS) and Uman (Um)] that differ significantly in longevity, as well as the life span of the progeny from the reciprocal crosses among them. The hybridization caused the increase in both flies’ mean and maximum life span mainly shifting the survival curves upward proportionally at all ages. This resulted in the reduction in the Gompertz intercept (frailty) whereas the Gompertz slope (the rate of aging) was predominantly unchanged. Better-parent heterosis was observed in hybrids between OR and Um inbred lines and the extent of heterosis was more pronounced in hybrids between CS and Um inbred lines if long-lived parent was used as the female parent, and short-lived parent was used as the male parent in the crossing scheme. Such discrepancy in life span between reciprocal crosses may indicate that non-chromosomal factors are significantly contributing to a heterotic response. Our data are in line with the previous reports suggesting the involvement of non-genomic factors, particularly epigenetic events attributed to hybridization, in the manifestation of heterosis.

First record of the invasive pest Drosophila suzukii in Ukraine indicates multiple sources of invasion

Drosophila suzukii, commonly known as the spotted-wing Drosophila, is an invasive polyphagous fruit pest, which has emerged as a global threat to agriculture in the Americas and in Europe. Due to the rapid spread, great economic losses and its pest behavior, D. suzukii represents a powerful model for invasion biology and pest management studies. However, its current European distribution, invasion routes and levels of genetic diversity in populations of D. suzukii are poorly understood. We present the first report of D. suzukii from Ukraine, with the invasion likely occurring close to 2014. The pattern of genetic variation at cytochrome oxidase I among D. suzukii populations from Europe, USA and Asia reveals comparatively high genetic diversity in the Ukrainian population of this pest species, suggesting a complex invasion scenario from multiple sources. Further monitoring patterns of genetic variation across space and time, to better understand the invasion routes of this invasive insect pest, will be an essential part for developing successful pest management strategies.

Comparative analysis of Deschampsia antarctica Desv. population adaptability in the natural environment of the Admiralty Bay region (King George Island, maritime Antarctic)

Plants inhabiting extreme environments may possess features allowing them to tolerate sudden abrupt changes in their environment, a phenomenon often known as ‘adaptability.’ However, ability or success in developing adaptability varies among plant populations. Adaptability can be quantified by measuring variation in the response to the same environmental challenges between plant populations. In this study, we evaluate the adaptability of the iconic Antarctic plant, Deschampsia antarctica, based on traits reflecting three levels of organization: the population level (S, D. antarctica land cover), individual level (Ph, biometrics), and cell level (relative DNA content, rcDNA, in cells of the leaf parenchyma). We sampled a total of six D. antarctica populations in the Admiralty Bay region, King George Island (South Shetland Islands, maritime Antarctic), during the austral summer of 2005–2006, and analyzed pairwise interrelations between various indices reflecting plant population adaptability. The results of these pairwise comparisons were then used to estimate a pooled measure of each population’s adaptability, designated as united latent quality indicator (ULQI). Our results demonstrated that the responses of individual adaptability indices were seldom synchronized, although one population from the central part of the Point Thomas oasis did show some degree of synchronicity. This population also demonstrated the highest ULQI, consistent with the relatively favorable microenvironmental conditions at this location. Two other populations located closer to the shoreline also demonstrated detectable synchronicity and moderate levels of ULQI, while the remaining populations revealed no synchronized responses and negative ULQI values. As the ULQI value obtained will be strongly influenced by the conditions experienced by any given population during a particular season, evaluation of population dynamics requires annual monitoring over multiple seasons.

Mechanisms of antarctic vascular plant adaptation to abiotic environmental factors

Native species of the Antarctic Deschampsia antarctica and Colobanthus quitensis exist at the limits of survival of vascular plants. Fundamental adaptations to abiotic environmental factors that qualitatively distinguish them from the other vascular plants of extreme regions, namely temperature, ultraviolet radiation hardiness, and their genetic plasticity in the changeable environment are discussed.

Role of the gene Miniature in Drosophila wing maturation.

Miniature is an extracellular zona pellucida domain‐containing protein, required for flattening of pupal wing epithelia in Drosophila. Here, we show that Miniature also plays an important role in the post‐eclosion wing maturation processes triggered by the neurohormone bursicon. Wing expansion and epithelial apoptosis are drastically delayed in miniature loss‐of‐function mutants, and sped up upon overexpression of the protein in wings. Miniature acts upstream from the heterotrimeric Gs protein transducing the bursicon signal in wing epithelia. We propose that Miniature interacts with bursicon and regulates its diffusion through or stability within the wing tissue. genesis 50:525–533, 2012.

Genomic analysis of European Drosophila melanogaster populations on a dense spatial scale reveals longitudinal population structure and continent-wide selection

Abstract Genetic variation is the fuel of evolution, with standing genetic variation especially important for short-term evolution and local adaptation. To date, studies of spatio-temporal patterns of genetic variation in natural populations have been challenging, as comprehensive sampling is logistically difficult, and sequencing of entire populations costly. Here, we address these issues using a collaborative approach, sequencing 48 pooled population samples from 32 locations, and perform the first continent-wide genomic analysis of genetic variation in European Drosophila melanogaster. Our analyses uncover longitudinal population structure, provide evidence for continent-wide selective sweeps, identify candidate genes for local climate adaptation, and document clines in chromosomal inversion and transposable element frequencies. We also characterise variation among populations in the composition of the fly microbiome, and identify five new DNA viruses in our samples.Genetic variation is the fuel of evolution. However, analyzing evolutionary dynamics in natural populations is challenging, sequencing of entire populations remains costly and comprehensive sampling logistically difficult. To tackle this issue and to define relevant spatial and temporal scales of variation, we have founded the European Drosophila Population Genomics Consortium (DrosEU). Here we present the first analysis of 48 D. melanogaster population samples collected across Europe in 2014. Our analysis uncovers novel patterns of variation at multiple levels: genome-wide neutral SNPs, mtDNA haplotypes, inversions, and TEs showing previously cryptic longitudinal population structure; signatures of selective sweeps shared among populations; presumably adaptive clines in inversions; and geographic variation in TEs. Additionally, we document highly variable microbiota and identify several new Drosophila viruses. Our study reveals novel aspects of the population biology of D. melanogaster and illustrates the power of extensive sampling and pooled sequencing of populations on a continent-wide scale.Genetic variation is the fuel of evolution. However, analyzing dynamics of evolutionary change in natural populations is challenging, genome sequencing of entire populations remains costly and comprehensive sample collection logistically challenging. To tackle this issue and to define relevant spatial and temporal scales of variation for a population genetic model system, the fruit fly Drosophila melanogaster, we have founded the European Drosophila Population Genomics Consortium (DrosEU). Our principal objective is to employ the strengths of this collaborative consortium to extensively sample and sequence natural populations on a continent-wide scale and across distinct timescales. Here we present the first analysis of the first DrosEU pool-sequencing dataset, consisting of 48 population samples collected across the European continent in 2014. The analysis of this comprehensive dataset uncovers novel patterns of variation at multiple levels: genome-wide neutral SNPs, mtDNA haplotypes, inversions and TEs that exhibit previously cryptic longitudinal population structure across the European continent; signatures of selective sweeps shared among the majority of European populations; presumably adaptive clines in inversions; and geographic variation in TEs. Additionally, we document highly variable microbiota among European fruit fly populations and identify several new Drosophila viruses. Our study reveals novel aspects of the population biology of D. melanogaster and illustrates the power of extensive sampling and pooled sequencing of natural populations on a continent-wide scale.

Longevity-modulating effects of symbiosis: insights from Drosophila–Wolbachia interaction

Microbial communities are known to significantly affect various fitness components and survival of their insect hosts, including Drosophila. The composition of symbiotic microbiota has been shown to change with the host’s aging. It is unclear whether these changes are caused by the aging process or, vice versa, they affect the host’s aging and longevity. Recent findings indicate that fitness and lifespan of Drosophila are affected by endosymbiotic bacteria Wolbachia. These effects, however, are inconsistent and have been reported both to extend and shorten longevity. The main molecular pathways underlying the lifespan-modulating effects of Wolbachia remain unclear, however insulin/insulin-like growth factor, immune deficiency, ecdysteroid synthesis and signaling and c-Jun N-terminal kinase pathways as well as heat shock protein synthesis and autophagy have been proposed to play a role. Here we revise the current evidence that elucidates the impact of Wolbachia endosymbionts on the aging processes in Drosophila.

DNA methylation in Drosophila melanogaster may depend on lineage heterogeneity

DNA methylation has been discovered in Drosophila only recently. Current evidence indicates that de novo methylation patterns in drosophila are maintained in a different way compared to vertebrates and plants. As the genomic role and determinants of DNA methylation are poorly understood in invertebrates, its link with several factors has been suggested. In this study, we tested for the putative link between DNA methylation patterns in Drosophila melanogaster and radiation or the activity of P transposon. Neither of the links were apparent from the results, however, we obtained some hints on a possible link between DNA methylation pattern and genomic heterogeneity of fly lineages.