A macroevolutionary role for chromosomal fusion and fission in Erebia butterflies.

The impact of large-scale chromosomal rearrangements, such as fusions and fissions, on speciation is a long-standing conundrum. We assessed whether bursts of change in chromosome numbers resulting from chromosomal fusion or fission are related to increased speciation rates in Erebia, one of the most species-rich and karyotypically variable butterfly groups. We established a genome-based phylogeny and used state-dependent birth-death models to infer trajectories of karyotype evolution. We demonstrated that rates of anagenetic chromosomal changes (i.e., along phylogenetic branches) exceed cladogenetic changes (i.e., at speciation events), but, when cladogenetic changes occur, they are mostly associated with chromosomal fissions rather than fusions. We found that the relative importance of fusion and fission differs among Erebia clades of different ages and that especially in younger, more karyotypically diverse clades, speciation is more frequently associated with cladogenetic chromosomal changes. Overall, our results imply that chromosomal fusions and fissions have contrasting macroevolutionary roles and that large-scale chromosomal rearrangements are associated with bursts of species diversification

Discovery of Hemilepistus (Hemilepistus) klugii (Brandt, 1833) (Isopoda, Oniscidea) in the Republic of Georgia with an overview of the ecology and biology of the subgenus

The terrestrial woodlice Hemilepistus (Hemilepistus) klugii (Brandt, 1833) is reported from Georgia for the first time, with a commentary on the species composition of the genus Hemilepistus Budde-Lund, 1879 in the Caucasus. A short review of the ecology of the subgenus H. (Hemilepistus) is also provided

Fine-scale analysis of habitat occupancy by Kura lizard (Darevskia portschinskii) and its daughter parthenogenetic form (Darevskia dahli)

Two species of rock lizards, the parthenogenetic D. dahli and the sexually reproducing D. portschinskii, coexist in a rocky outcrop in an area of ca. 1 ha, in the vicinity of Tbilisi, Georgia; the location has been well-known since the middle 1960s. The population density of the parthenogenetic lizard is five times higher than that of the sexual breeder. We studied the distribution of active lizards in space and time over three consecutive years, during the spring and autumn activity periods, to explore spatial and temporal differences between the species on a fine spatial scale. We studied the influence of temperature, humidity, and quantitative characteristics of the surface and the distance from permanent water source on the spatial distribution of D. dahli and D. portschinskii. Darevskia portschinskii was less dependent on the distance from the water source and more evenly distributed in space and time than D. dahli. Despite potential competitive interactions, the species did not avoid each other on the microhabitat scale, suggesting that the observed ecological differences are not caused by a niche shift. More individuals of the sexual breeder than individuals of the parthenogen were found in suboptimal habitats. This feature may increase the evolutionary success of D. portschinskii in a long-term perspective

Two-headed parthenogenetic lizard embryo from southern Georgia

Abstract Visual inspection of several embryos of the parthenogenetic lizard Darevskia armeniaca revealed the presence of an embryo with axial bifurcation (“two-headed”) on the stage of pigmented eyes and plate-like limb buds with a distinct border at the edges. This is the third recorded case of axial bifurcation in D. armeniaca, although two previous cases were mentioned without further discussion. Here the bicephalic embryo is described in detail and the potential reasons are discussed. The analysis of the literature on axial bifurcation in lacertids suggests that this type of developmental disorder may be particularly common in this parthenogenetic form. Hybridization may cause multiple developmental disorders, including incomplete separation of twin embryos; all parthenogenetic Darevskia have a hybrid origin, and this may cause the disorders rather than parthenogenetic reproduction by itself. The hypothesis needs further study with more representative samples of parthenogenetic and sexually reproducing Darevskia

New and well-forgotten: DNA-assisted records of two beetle (Insecta, Coleoptera) species new for the fauna of Georgia with an update on the distribution of some other little studied taxa

First records of two species of beetles (Insecta, Coleoptera), namely Pocadius adustus Reitter, 1888 (Nitidulidae) and Byrrhus pustulatus (Forster, 1770) (Byrrhidae) are given for Georgia. In addition, an update on the occurrences of Necrobia violacea (Linnaeus, 1758) (Cleridae), Coelostoma orbiculare (Fabricius, 1775) (Hydrophilidae) and Lycoperdina succincta (Linnaeus, 1767) (Endomychidae) are also presented based on the specimens collected in Samtskhe-Javakheti region, determined by morphological and mtDNA barcoding methods

Precise paternal ancestry of hybrid unisexual ZW lizards (genus Darevskia: Lacertidae: Squamata) revealed by Z-linked genomic markers

We genotyped multiple populations of all seven parthenogenetic species of rock lizards, genus Darevskia, as well as their putative sexual parental populations, using double digest RAD-sequencing genomic markers. Taking advantage of the conserved homology of the ZW/ZZ sex chromosomes among lacertid lizards, we aligned our short sequence reads to a reference Z chromosome assembly of the common wall lizard Podarcis muralis. This provided unique insight into the origin of all-female hybrid populations, which inherited their single Z chromosome exclusively from a paternal ancestor. The mapped Z-linked loci were used to construct a robust time-calibrated phylogeny. In each parent-offspring species pair, the geographically nearest population of the paternal species was identified as the most likely ancestor of the respective parthenogen, mirroring the trend observed previously on the maternal side in mitochondrial DNA. The estimated splits between the sampled paternal sexual ancestors and their daughter species occurred much earlier than suggested previously and during two narrow time periods: (1) the parthenogenetic Darevskia armeniaca, D. dahli, D. uzzelli and D. rostombekowi dated back to similar to 0.5 or similar to 0.9 Mya, depending on the calibration point used, while (2) D. bendimahiensis, D. sapphirina and D. unisexualis appear to have diverged similar to 1 or similar to 2 Mya

Into the unknown: the first barcode-assisted checklist of Psocoptera (Insecta, Psocodea) of Georgia with a census on country species richness

This checklist reports 47 species of Psocoptera from 15 families and three suborders from Georgia, of which 31 species are recorded for the first time, increasing the known fauna of the country by more than 65%. Of these, 37 species have been barcoded, representing 210 Barcode Identification Numbers (BINs). An additional 14 species are expected to occur in Georgia but remain undiscovered, meaning that only ≈ 77% of the fauna is currently documented. Barcodes, comments on distributions, and images of voucher specimens are given followed by a map of the sampling sites

Genotypic similarities among the parthenogenetic Darevskia rock lizards with different hybrid origins

Abstract Background The majority of parthenogenetic vertebrates derive from hybridization between sexually reproducing species, but the exact number of hybridization events ancestral to currently extant clonal lineages is difficult to determine. Usually, we do not know whether the parental species are able to contribute their genes to the parthenogenetic vertebrate lineages after the initial hybridization. In this paper, we address the hypothesis, whether some genotypes of seven phenotypically distinct parthenogenetic rock lizards (genus Darevskia) could have resulted from back-crosses of parthenogens with their presumed parental species. We also tried to identify, as precise as possible, the ancestral populations of all seven parthenogens. Results We analysed partial mtDNA sequences and microsatellite genotypes of all seven parthenogens and their presumed ansectral species, sampled across the entire geographic range of parthenogenesis in this group. Our results confirm the previous designation of the parental species, but further specify the maternal populations that are likely ancestral to different parthenogenetic lineages. Contrary to the expectation of independent hybrid origins of the unisexual taxa, we found that genotypes at multiple loci were shared frequently between different parthenogenetic species. The highest proportions of shared genotypes were detected between (i) D. sapphirina and D. bendimahiensis and (ii) D. dahli and D. armeniaca, and less often between other parthenogens. In case (ii), genotypes at the remaining loci were notably distinct. Conclusions We suggest that both observations (i-ii) can be explained by two parthenogenetic forms tracing their origin to a single initial hybridization event. In case (ii), however, occasional gene exchange between the unisexual and the parental bisexual species could have taken place after the onset of parthenogenetic reproduction. Indeed, backcrossed polyploid hybrids are relatively frequent in Darevskia, although no direct evidence of recent gene flow has been previously documented. Our results further suggest that parthenogens are losing heterozygosity as a result of allelic conversion, hence their fitness is expected to decline over time as genetic diversity declines. Backcrosses with the parental species could be a rescue mechanism which might prevent this decline, and therefore increase the persistance of unisexual forms