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9 result(s) for "Pazhenkova, Elena"
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Chromosomal conservatism vs chromosomal megaevolution: enigma of karyotypic evolution in Lepidoptera
In the evolution of many organisms, periods of slow genome reorganization (= chromosomal conservatism) are interrupted by bursts of numerous chromosomal changes (= chromosomal megaevolution). Using comparative analysis of chromosome-level genome assemblies, we investigated these processes in blue butterflies (Lycaenidae). We demonstrate that the phase of chromosome number conservatism is characterized by the stability of most autosomes and dynamic evolution of the sex chromosome Z, resulting in multiple variants of NeoZ chromosomes due to autosome-sex chromosome fusions. In contrast during the phase of rapid chromosomal evolution, the explosive increase in chromosome number occurs mainly through simple chromosomal fissions. We show that chromosomal megaevolution is a highly non-random canalized process, and in two phylogenetically independent Lysandra lineages, the drastic parallel increase in number of fragmented chromosomes was achieved, at least partially, through reuse of the same ancestral chromosomal breakpoints. In species showing chromosome number doubling, we found no blocks of duplicated sequences or duplicated chromosomes, thus refuting the hypothesis of polyploidy. In the studied taxa, long blocks of interstitial telomere sequences (ITSs) consist of (TTAGG)n arrays interspersed with telomere-specific retrotransposons. ITSs are sporadically present in rapidly evolving Lysandra karyotypes, but not in the species with ancestral chromosome number. Therefore, we hypothesize that the transposition of telomeric sequences may be triggers of the rapid chromosome number increase. Finally, we discuss the hypothetical genomic and population mechanisms of chromosomal megaevolution and argue that the disproportionally high evolutionary role of the Z sex chromosome can be additionally reinforced by sex chromosome—autosome fusions and Z-chromosome inversions.
Whole-Genome Analysis Reveals the Dynamic Evolution of Holocentric Chromosomes in Satyrine Butterflies
Butterfly chromosomes are holocentric, i.e., lacking a localized centromere. Potentially, this can lead to rapid karyotypic evolution through chromosome fissions and fusions, since fragmented chromosomes retain kinetic activity, while fused chromosomes are not dicentric. However, the actual mechanisms of butterfly genome evolution are poorly understood. Here, we analyzed chromosome-scale genome assemblies to identify structural rearrangements between karyotypes of satyrine butterfly species. For the species pair Erebia ligea–Maniola jurtina, sharing the ancestral diploid karyotype 2n = 56 + ZW, we demonstrate a high level of chromosomal macrosynteny and nine inversions separating these species. We show that the formation of a karyotype with a low number of chromosomes (2n = 36 + ZW) in Erebia aethiops was based on ten fusions, including one autosome–sex chromosome fusion, resulting in a neo-Z chromosome. We also detected inversions on the Z sex chromosome that were differentially fixed between the species. We conclude that chromosomal evolution is dynamic in the satyrines, even in the lineage that preserves the ancestral chromosome number. We hypothesize that the exceptional role of Z chromosomes in speciation may be further enhanced by inversions and sex chromosome–autosome fusions. We argue that not only fusions/fissions but also inversions are drivers of the holocentromere-mediated mode of chromosomal speciation.
Genetic Rescue of the Dinaric Lynx Population: Insights for Conservation From Genetic Monitoring and Individual‐Based Modelling
Inbreeding depression poses a severe threat to small populations, leading to the fixation of deleterious mutations and decreased survival probability. While the establishment of natural gene flow between populations is an ideal long‐term solution, its practical implementation is often challenging. Reinforcement of populations by translocating individuals from larger populations is a viable strategy for reducing inbreeding, increasing genetic diversity and potentially saving populations from extinction. The Dinaric population of Eurasian lynx (Lynx lynx) has faced high inbreeding levels, with effective inbreeding reaching 0.316 in 2019, endangering the population's survival. To counteract this, population reinforcement was implemented between 2019 and 2023, involving the translocation of 12 individuals from the Carpathian Mountains to the Dinaric Mountains of Slovenia and Croatia. We conducted comprehensive genetic monitoring in this area, gathering 588 non‐invasive and tissue samples, which were used for individual identification and estimation of population genetic parameters. We used stochastic modelling to assess the long‐term viability of the Dinaric lynx population post‐translocation and formulate effective conservation strategies. The model predicts that, despite significant improvement of genetic diversity after translocations, inbreeding will return to critical levels within 45 years. Our results highlight the fact that reinforcement is just the first step and that long‐term genetic management is needed to keep the population from sliding back towards extinction. The Dinaric lynx population serves as a compelling example of genetic rescue. The lessons learnt here will be essential for ensuring the viability of the Dinaric lynx in the future and also provide a useful template for conservation of other populations and species facing similar threats.
Chromosomal and mitochondrial diversity in Melitaea didyma complex (Lepidoptera, Nymphalidae): eleven deeply diverged DNA barcode groups in one non-monophyletic species?
It is generally accepted that cases of species' polyphyly in trees arising as a result of deep intraspecific divergence are negligible, and the detected cases reflect misidentifications or/and methodological errors. Here we studied the problem of species' non-monophyly through chromosomal and molecular analysis of butterfly taxa close to (Esper, 1779) (Lepidoptera, Nymphalidae). We found absence or low interspecific chromosome number variation and presence of intraspecific variation, therefore we conclude that in this group, chromosome numbers have relatively low value as taxonomic markers. Despite low karyotype variability, the group was found to have unexpectedly high mitochondrial haplotype diversity. These haplotypes were clustered in 23 highly diverged haplogroups. Twelve of these haplogroups are associated with nine traditionally recognized and morphologically distinct species Moore, 1901, Oberthür, 1909, Eversmann, 1847, Higgins, 1941, Colenati, 1846, Eversmann, 1847, Evans, 1912, Christoph, 1873 and Staudinger, 1892. The rest of the haplogroups (11 lineages) belong to a well-known west-palaearctic species . The last species is particularly unusual in the haplotypes we obtained. First, it is clearly polyphyletic with respect to gene. Second, the differentiation in gene between these mostly allopatric (but in few cases sympatric) eleven lineages is extremely high (up to 7.4%), i.e. much deeper than the \"standard\" DNA barcode species threshold (2.7-3%). This level of divergence normally could correspond not even to different species, but to different genera. Despite this divergence, the bearers of these haplogroups were found to be morphologically indistinguishable and, most importantly, to share absolutely the same ecological niches, i.e. demonstrating the pattern which is hardly compatible with hypothesis of multiple cryptic species. Most likely such a profound irregularity in barcodes is caused by reasons other than speciation and represents an extraordinary example of intra-species barcode variability. Given the deep level of genetic differentiation between the lineages, we assume that there was a long period (up to 5.0 My) of allopatric differentiation when the lineages were separated by geographic or/and ecological barriers and evolved in late Pliocene and Pleistocene refugia of north Africa, the Iberian and Balkan Peninsulas, the Middle East and Central Asia. We discuss the refugia-within-refugia concept as a mechanism explaining the presence of additional diverged minor haplogroups within the areas of the major haplogroups. We also provide the first record of in Azerbaijan and the record of as a new taxon for Russia and Europe.
DNA barcoding reveals twelve lineages with properties of phylogenetic and biological species within Melitaea didyma sensu lato (Lepidoptera, Nymphalidae)
The complex of butterfly taxa close to Melitaea didyma includes the traditionally recognized species Melitaea didyma, Melitaea didymoides and Melitaea sutschana, the taxa that were recognized as species only relatively recently (Melitaea latonigena, Melitaea interrupta, Melitaea chitralensis and Melitaea mixta) as well as numerous described subspecies and forms with unclear taxonomic status. Here analysis of mitochondrial DNA barcodes is used to demonstrate that this complex is monophyletic group consisting of at least 12 major haplogroups strongly differentiated with respect to the gene COI. Six of these haplogroups are shown to correspond to six of the above-mentioned species (Melitaea didymoides, Melitaea sutschana, Melitaea latonigena, Melitaea interrupta, Melitaea chitralensis and Melitaea mixta). It is hypothesized that each of the remaining six haplogroups also represents a distinct species (Melitaea mauretanica, Melitaea occidentalis, Melitaea didyma, Melitaea neera, Melitaea liliputana and Melitaea turkestanica), since merging these haplogroups would result in a polyphyletic assemblage and the genetic distances between them are comparable with those found between the other six previously recognized species.
Mitochondrial chromosome as a marker of animal migratory routes: DNA barcoding revealed Asian (non-African) origin of a tropical migrant butterfly Junonia orithya in south Israel
The blue pansy Linnaeus, 1758 (Lepidoptera, Nymphalidae) is widely distributed along the tropical areas of Africa, Asia and Australia. It is also known as a migrant species in the Levant. Here we record in south Israel and provide a DNA-barcode-based evidence for its Asian (non-African) origin.
Restoration of the tree-nesting Peregrine Falcon (Falco peregrinus) population in the Volga-Ural Region
We have applied the method of a forming tree-nesting behavior pattern in the chicks of the cliff-nesting Peregrine Falcon. In June 2016 and 2017, in the Southern Ural Mountains and Bugulma-Belebey Upland, we discovered four nests of Peregrine Falcons, which were threatened by destruction due to various anthropogenic and biological factors. For preventing the death of the broods, the chicks were transferred from the occupied nesting niches in the rock cliffs to nesting platforms. On nesting platforms they spent from 3 to 12 days where they were fed by adults regularly. All four broods (9 young) flew out successfully and demonstrated typical behavior for the Peregrines of their age. Adults fed fledglings and taught them to hunt.
Saving the Dinaric lynx: multidisciplinary monitoring and stakeholder engagement support large carnivore restoration in human-dominated landscape
Translocations are central to large carnivore restoration efforts, but inadequate monitoring often inhibits effective conservation decision-making. Extinctions, reintroductions, poaching and high inbreeding levels of the Central European populations of Eurasian lynx (Lynx lynx) typify the carnivore conservation challenges in the Anthropocene. Recently, several conservation efforts were initiated to improve the genetic and demographic status, but were met with variable success. Here, we report on a successful, stakeholder-engaged translocation effort to reinforce the highly-inbred Dinaric lynx population and create a new stepping-stone subpopulation in the Southeastern Alps. We used multidisciplinary and internationally-coordinated monitoring using systematic camera- trapping, non-invasive genetic sampling, GPS-tracking of translocated and remnant individuals, recording of reproductive events and interspecific interactions, as well as the simultaneous tracking of the public and stakeholders’ support of carnivore conservation before, during and after the translocation process across the three countries. Among the 22 translocated wild-caught Carpathian lynx, 68% successfully integrated into the population and local ecosystems and at least 59% reproduced. Probability of dispersing from the release areas was 3-times lower when soft-release rather than hard-release method was used. Translocated individuals had lower natural mortality, higher reproductive success and similar ungulate kill rates compared to the remnant lynx. Cooperation with local hunters and protected area managers enabled us to conduct multi-year camera-trapping and non-invasive genetic monitoring across a 12,000-km2 transboundary area. Results indicate a reversal in population decline, as the lynx abundance increased for >40% during the 4-year translocation period. Effective inbreeding decreased from 0.32 to 0.08-0.19, suggesting a 2- to 4-fold increase in fitness. Furthermore, successful establishment of a new stepping-stone subpopulation represents an important step towards restoring the Central European lynx metapopulation. Robust partnerships with local communities and hunters coupled with transparent communication helped maintain high public and stakeholder support for lynx conservation throughout the translocation process. Lessons learned about the importance of stakeholder involvement and multidisciplinary monitoring conducted across several countries provide a successful example for further efforts to restore large carnivores in human-dominated ecosystems.