Alexander Gavashelishvili

Geographic and genetic boundaries of brown bear (Ursus arctos) population in the Caucasus

The taxonomic status of brown bears in the Caucasus remains unclear. Several morphs or subspecies have been identified from the morphological (craniological) data, but the status of each of these subspecies has never been verified by molecular genetic methods. We analysed mitochondrial DNA sequences (control region) to reveal phylogenetic relationships and infer divergence time between brown bear subpopulations in the Caucasus. We estimated migration and gene flow from both mitochondrial DNA and microsatellite allele frequencies, and identified possible barriers to gene flow among the subpopulations. Our suggestion is that all Caucasian bears belong to the nominal subspecies of Ursus arctos. Our results revealed two genetically and geographically distinct maternal haplogroups: one from the Lesser Caucasus and the other one from the Greater Caucasus. The genetic divergence between these haplogroups dates as far back as the beginning of human colonization of the Caucasus. Our analysis of the least‐cost distances between the subpopulations suggests humans as a major barrier to gene flow. The low genetic differentiation inferred from microsatellite allele frequencies indicates that gene flow between the two populations in the Caucasus is maintained through the movements of male brown bears. The Likhi Ridge that connects the Greater and Lesser Caucasus mountains is the most likely corridor for this migration.

Modelling the range of Syrian spadefoot toad (Pelobates syriacus) with combination of GIS-based approaches

Syrian spadefoot toads (Pelobates syriacus) are found from Balkan Peninsula throughout the Caucasus, Middle East, and Northern Iran. However, the range of this species is sufficiently mapped only in Balkans. Based on the detailed mapping of the species in Georgia, we analysed the environmental factors influencing species occurrence and produced spatial models for the entire range. Nine models based on the logistic regression, discriminant function analysis, and classification tree analysis, all showed significant influence of the vegetation index and maximum summer temperature on the species distribution. The habitat suitability models based on the presence-only data (Mahalanobis distance estimation and Maximum Entropy approach) had a better performance than the models based on the presence-absence data. The habitat suitability models included two variables only, identified as significant in all preliminary analyses. The area identified as suitable by presence-only models strongly increases when a few environmental variables are included in the analysis. When only two variables are considered, the model predicted large areas north of the actual range. Competition with the related common spadefoot toad (P. fuscus) might have a role on the position of the northern limit of the range of P. syriacus. Within the predicted range, use of breeding sites is negatively associated with presence of fish. Breeding pond preferences of P. syriacus were particularly similar to those of the lake frog (Rana ridibunda), although the latter species uses appropriate habitats more extensively.

Movements and habitat use by immature Cinereous Vultures (Aegypius monachus) from the Caucasus

Capsule Juvenile and immature Cinereous Vultures from the Caucasus move large distances across undeveloped open-dry habitats in response to snowfall or high summer temperatures. Aim To study local and long-range movements of Cinereous Vulture (Aegypius monachus), and investigate the influence of environmental variables on spatial and temporal distributions of the species on a large scale. Methods We use 4-year-long location data from 6 juvenile Cinereous Vultures fitted with satellite-received transmitters to track their movements and obtain habitat suitability models. Results A few months after fledging, Cinereous Vultures may migrate from the Caucasus as far south as the Arabian Peninsula. Their movements are concentrated in undeveloped open-dry habitats. High temperatures push the vultures to higher latitudes and altitudes, while reverse seasonal movements are triggered by the extent of snow cover. Conclusions Our study shows the importance of the Arabian Peninsula and Iran as wintering areas for Cinereous Vultures. Long-distance movements by immature cinereous vultures are determined by climate seasonality, and in light of climate-warming scenarios for the next 100 years, there might be a shift in timing of the onset of the species seasonal movements and a change in the duration and geography of its wintering and summering.

Planning the conservation of the breeding population of cinereous vultures Aegypius monachus in the Republic of Georgia

Occupied and potential nesting areas of Near Threatened cinereous vulture Aegypius monachus in the Republic of Georgia were examined to model its nesting habitat. The intention is to support its conservation within the context of the ongoing establishment of a system of protected areas. Data were manipulated and analysed using a geographical information system, univariate statistical analysis and logistic regression. The best model suggested that in Georgia plots were more likely to contain a cinereous vulture nest if the slope was >30° and faced north, was situated in rugged terrain away from unprotected and populated areas, and was relatively dry. North-facing slopes were where suitable nest trees could be found, whereas ruggedness, protected areas and remoteness from populated areas made access to the nest trees by humans difficult. Low annual rainfall provided better soaring and breeding conditions. The model suggested that the breeding range of cinereous vulture in Georgia could expand if seasonal grazing, which is the primary source of disturbance, is properly managed. Because neither nesting places nor food availability appeared to be limiting, human disturbance and climate seem to best explain the current distribution of nesting cinereous vultures in Georgia, and probably elsewhere in the Caucasus.

Human Paternal Lineages, Languages, and Environment in the Caucasus

ABSTRACT Publications that describe the composition of the human Y-DNA haplogroup in different ethnic or linguistic groups and geographic regions provide no explicit explanation of the distribution of human paternal lineages in relation to specific ecological conditions. Our research attempts to address this topic for the Caucasus, a geographic region that encompasses a relatively small area but harbors high linguistic, ethnic, and Y-DNA haplogroup diversity. We genotyped 224 men that identified themselves as ethnic Georgian for 23 Y-chromosome short tandem-repeat markers and assigned them to their geographic places of origin. The genotyped data were supplemented with published data on haplogroup composition and location of other ethnic groups of the Caucasus. We used multivariate statistical methods to see if linguistics, climate, and landscape accounted for geographical differences in frequencies of the Y-DNA haplogroups G2, R1a, R1b, J1, and J2. The analysis showed significant associations of (1) G2 with well-forested mountains, (2) J2 with warm areas or poorly forested mountains, and (3) J1 with poorly forested mountains. R1b showed no association with environment. Haplogroups J1 and R1a were significantly associated with Daghestanian and Kipchak speakers, respectively, but the other haplogroups showed no such simple associations with languages. Climate and landscape in the context of competition over productive areas among different paternal lineages, arriving in the Caucasus in different times, have played an important role in shaping the present-day spatial distribution of patrilineages in the Caucasus. This spatial pattern had formed before linguistic subdivisions were finally shaped, probably in the Neolithic to Bronze Age. Later historical turmoil had little influence on the patrilineage composition and spatial distribution. Based on our results, the scenario of postglacial expansions of humans and their languages to the Caucasus from the Middle East, western Eurasia, and the East European Plain is plausible.

Landscape Complexity in the Caucasus Impedes Genetic Assimilation of Human Populations More Effectively than Language or Ethnicity

ABSTRACT The analyses of 15 autosomal and 23 Y-chromosome DNA single-tandem-repeat loci in five rural populations from the Caucasus (four ethnically Georgian and one ethnically Armenian) indicated that two Georgian populations, one from the west and the other from the east of the Greater Caucasus Mountains, were both patrilineally and autosomally most differentiated from each other, and the other populations of Georgians and Armenians held an intermediate position between those two. This pattern may be due to human dispersal from two distinct glacial refugia in the last glacial period and the early Holocene, followed by less gene flow among the populations from the Greater Caucasus than among those from the rest of the Caucasus, where the populations have undergone substantial admixture in historical time. This hypothesis is supported by a strong correlation between genetic differentiation among the populations and landscape permeability to human migrations as determined by terrain ruggedness, forest cover, and snow cover. Although geographic patterns of autosomal and Y-chromosome DNA are not fully concordant, both are influenced by landscape permeability and show a similar east-west gradient. Our results suggest that this permeability was a stronger factor limiting gene flow among human populations in the Caucasus than were ethnic or linguistic boundaries.

Modeling the distribution and abundance of eastern tur (Capra cylindricornis) in the Caucasus

Our research attempts 1) to link the distribution and abundance of eastern tur (Capra cylindricornis) to environmental variables varying in space and time, and 2) to identify environmental constraints that may have caused the geographic segregation of eastern tur from western tur (Capra caucasica). Our results suggest that 1) eastern tur are heat-sensitive but prefer snow-free, grass-dominated areas near escape cliffs, and in terrain that is difficult for humans and livestock to reach; and 2) present-day genetic and phenotypic differences between the Capra species are largely related to discontinuity of and impeded migration between Capra populations during glacial periods, and insufficient time in the postglacial period for now-adjoining Capra populations to overcome behavioral mechanisms impeding hybridization in the wild so as to erase these differences.