Control Region Fragment Research Articles

Genetic structure of the commercially important Asian monsoon scallop, Amusium pleuronectes (Linnaeus 1758), across the Indonesian Archipelago

AbstractThe Asian monsoon scallop, Amusium pleuronectes, is a key member of the most commercially harvested shellfish community in Asia. Patterns of genetic diversity and natural population structure in the target species were investigated to gain a better understanding of its evolutionary history. Samples were collected from five sites across the Indonesian Archipelago. We characterized sequence variation in an mtDNA control region fragment in 249 individuals. The genetic diversity (h = ranging from 0.83 to 0.92) and nucleotide diversity (π = ranging from 0.24 to 0.32) were low compared to the estimates reported for many other similar shellfish taxa. Nonetheless, analysis of molecular variance revealed significant genetic differentiation, FST = 0.0203 (p < .005 after Bonferroni corrections). Furthermore, both Pairwise fixation index values showed significance among majority population sites, indicating that dispersal potential and gene flow were low in the past. This pattern likely reflects a low dispersal potential, potentially allowing local adaptation to sites that augment any oceanographic and geographic contribution to genetic structure. The results described herein provide a foundation for developing better conservation strategies for the target species in the future.

Reducing the transcriptional read-through rate of a lentiviral vector for β-thalassemia gene therapy.

LentiGlobin BB305 is a self-inactivating lentiviral vector carrying a human β-globin expressing cassette for treating β-thalassemia. Initially, a 2 × 250 bp chicken Locus Control Region fragment of cHS4, functioning as an insulator, was placed at its ΔU3, which was removed after the first clinical trial led by a French team to avoid abnormal splicing, etc. This action could potentially lead to an increasing risk of the transcriptional read-through rate driven by the β-globin promoter to a significant level, posing a biosafety risk in clinical trials. In the present study, a read-through reducing agent (C-U+ or WPRE) was designed to be placed at the 3' UTR of the β-globin gene. The Enhancer Activities and/or Transcriptional Read-Through (EATRT) rate at the mRNA level and the protein expression level regarding lentiviral preparation titer were examined. We found that the insertion of the element (C-U+ or WPRE) reduced the EATRT effectively by 53% or 41%, respectively. C-U+ has less impact on virus package efficiency. Furthermore, there was no significant difference in the protein expression level after the C-U+ or WPRE insertion. The results of the present study show that inserting C-U+ or WPRE before the polyA sequence of the BB305 would reduce the EATRT rate at no cost of its expressing efficacy and viral preparation titers. Thus, we present an alternative improvement for a safer lentiviral vector for β-thalassemia clinical trials.

Guidelines and quantitative standards for improved cetacean taxonomy using full mitochondrial genomes.

In many organisms, especially those of conservation concern, traditional lines of evidence for taxonomic delineation, such as morphological data, are often difficult to obtain. In these cases, genetic data are often the only source of information available for taxonomic studies. In particular, population surveys of mitochondrial genomes offer increased resolution and precision in support of taxonomic decisions relative to conventional use of the control region or other gene fragments of the mitochondrial genome. To improve quantitative guidelines for taxonomic decisions in cetaceans, we build on a previous effort targeting the control region and evaluate, for whole mitogenome sequences, a suite of divergence and diagnosability estimates for pairs of recognized cetacean populations, subspecies, and species. From this overview, we recommend new guidelines based on complete mitogenomes, combined with other types of evidence for isolation and divergence, which will improve resolution for taxonomic decisions, especially in the face of small sample sizes or low levels of genetic diversity. We further use simulated data to assist interpretations of divergence in the context of varying forms of historical demography, culture, and ecology.

Population genetic structure and mixed stock analysis of the green sea turtle, Chelonia mydas, reveal reproductive isolation in French Polynesia

The green turtle, Chelonia mydas, is a migratory marine species with a circumglobal distribution in tropical and temperate waters. Its natal homing behavior leads to a complex genetic structure with genetically differentiated populations that breed separately and mix within the same foraging grounds. Delineating the boundaries of these populations and their connectivity to feeding grounds is important for the management of this species, classified as endangered on the IUCN red list. Here, we examined the genetic structure and the origin of the green turtle in French Polynesia with 239 samples collected during nesting or hatchling events and 204 samples collected outside of nesting events, across 21 islands. Amplification of the 770pb mtDNA control region fragment, the standard base used to characterize haplotype diversity in this species, revealed 23 haplotypes including three novel ones, belonging to 6 different lineages. Haplotype diversity in the rookeries was 0.615, and nucleotide diversity was 0.019, values similar to those in the North West Pacific and Western Indian Oceans, two regions recognized as genetic diversity hotspots for C. mydas. The genetic structure between the Leeward and Windward Islands of the Society archipelago was found to be significant with pairwise Fst index and φst distance. Island groups (Windward Islands, Leeward Islands, Tuamotu) were genetically different from all other identified Pacific management units, with a weak differentiation between American Samoa and Leeward Islands. A mixed-stock analysis for the French Polynesian mixture revealed an exclusive contribution from the French Polynesian rookeries, with negligible input from the other Pacific populations. This study provides the first assessment of the genetic structure of green turtle populations within French Polynesia and fills an essential data gap regarding the genetic diversity of the species and its connectivity to other feeding grounds in the Pacific Ocean. The French Polynesian populations appear to be important contributors to the overall genetic diversity of the species, isolated from other Pacific populations, thus making them essential within the Pacific region. These results have important implications for the conservation of the species at both local and regional scales.

Genetic diversity among five native Thai chickens and Khiew-Phalee chickens in lower-northern Thailand using mitochondrial DNA barcodes

Abstract. Siriwadee P, Wirot L, Thanapol P, Wirawan N. 2023. Genetic diversity among five native Thai chickens and Khiew-Phalee chickens in lower-northern Thailand using mitochondrial DNA barcodes. Biodiversitas 24: 1962-1970. Native chickens are an important biological resource in Thailand, with each breed having distinctive features. Khiew-Phalee chickens are a valuable investment in cultural wisdom and an invaluable Thai resource worthy of conservation. It is the royal rooster of Phraya Phichai Dab Hak. Due to a crisis concerning a sharp decline in the size of the Khiew-Phalee native chicken population, the identification of potential biomarkers is important for the determination of different chicken breeds for future planning. This study aimed to investigate the molecular identification of different native Thai chicken breeds based on mitochondrial DNA (mtDNA) barcodes, especially Khiew-Phalee chickens, which is difficult using the morphological examination. Partial sequences of 648 bp mtDNA control region fragments were determined for 53 specimens of six breeds of native Thai chickens (Khiew-Phalee, Thao Thong, Leung Hang Khao, Chee, Pra Dhu Hang Dam and Kai Jae). Genetic diversity was accessed based on the number of polymorphic sites, number of haplotypes, haplotype diversity, nucleotide diversity, and average number of differences. A phylogenetic tree was constructed based on maximum likelihood. The results showed that eighteen haplotypes were identified from 9 polymorphic sites with polymorphism between nucleotides 1074, 1107, 1109, 1177, 1213, 1214, 1268, 1276 and 1305. The haplotype diversity, nucleotide diversity, and the average number of differences for all chickens were 0.917, 0.00504 and 2.69086, respectively. All Khiew-Phalee chickens showed 7 haplotypes with 0.897 haplotype diversity, 0.00696 nucleotide diversity, and an average number of differences at 3.1795 clustered with other breeds in the phylogenetic tree. The findings indicated that the DNA barcoding gene is an effective method to identify the Khiew-Phalee and five other native Thai chicken breeds. It is a better choice for using molecular biology DNA barcoding to identify Thai native chicken breeds to plan for further conservation and development by the Department of Livestock Development of Thailand.

New haplotypes found in stranded long‐finned pilot whales (Globicephala melas) in the eastern North Atlantic and adjacent waters

AbstractLong‐finned pilot whale (Globicephala melas) mitochondrial (mtDNA) genetic diversity is considered low, especially in the North Atlantic, where only seven haplotypes have been recorded in previous studies using a 345 bp control region fragment. Such studies have not included samples from Ireland or the Netherlands. In this study we analyzed a longer sequence of the mtDNA control region (631 bp) from individuals stranded around Ireland, Scotland, and the Netherlands between 1995 and 2019 (n = 180). Nine haplotypes were identified, of which five were newly described (haplotype diversity h = 0.511). Pairwise tests revealed significant differentiation between the Irish and Scottish samples. Potential confounding factors are discussed but given that failure to recognize population structure may compromise conservation efforts, the findings show the need for further investigation using nuclear markers. Six mass stranding events were included, of which one event reported two haplotypes among individuals confirming a mixing of matrilineal groups. Although the permanence of this combination cannot be determined, this is the first record of such an occurrence within the North Atlantic. This study shows that stranding sample databases are a useful resource for genetic studies and provides new insights into genetic diversity of long‐finned pilot whales in the eastern North Atlantic and adjacent waters.

Demographic history and genetic diversity of wild African harlequin quail (Coturnix delegorguei delegorguei) populations of Kenya.

Hunting wild African harlequin quails (Coturnix delegorguei delegorguei) using traditional methods in Western Kenya has been ongoing for generations, yet their genetic diversity and evolutionary history are largely unknown. In this study, the genetic variation and demographic history of wild African harlequin quails were assessed using a 347bp mitochondrial DNA (mtDNA) control region fragment and 119,339 single nucleotide polymorphisms (SNPs) from genotyping‐by‐sequencing (GBS) data. Genetic diversity analyses revealed that the genetic variation in wild African harlequin quails was predominantly among individuals than populations. Demographic analyses indicated a signal of rapid demographic expansion, and the estimated time since population expansion was found to be 150,000–350,000 years ago, corresponding to around the Pliocene–Pleistocene boundary. A gradual decline in their effective population size was also observed, which raised concerns about their conservation status. These results provide the first account of the genetic diversity of wild African harlequin quails of Siaya, thereby creating a helpful foundation in their biodiversity conservation.

High genetic diversity detected in the mitochondrial Control Region of the Serra Spanish Mackerel, Scomberomorus brasiliensis (Collette, Russo & Zavala, 1978) along the Brazilian coast

The Serra Spanish mackerel, Scomberomorus brasiliensis, is one of the most important fishery resources in the western tropical Atlantic, including northern and eastern Brazil. Despite its economic importance, few genetic markers have been sequenced in this species, and little is known of its population genetics. The present study evaluated the genetic variability of 110 individuals, representing three distinct Brazilian populations (Macapá, Fortaleza and Paranaguá), based on a segment of the mitochondrial Control Region. The sequences revealed high levels of genetic diversity, and suggested marked connectivity among the studied populations. A variable repeat was also found in the 3’ portion of the studied Control Region fragment, which may prove useful as a marker in future genetic population studies of S. brasiliensis.

Signs of Genetic and Morphometric Population Differentiation in Small Planctivorous Seabird, Parakeet Auklet Aethia psittacula, Reinforces Linkage between Population Structure and Migratory Strategy

Study of population genetic structure is essential for insight in species biology, but mechanisms of its formation and factors influencing it remain insufficiently understood. Here we analyzed differentiation among populations in small colonial seabird of North Pacific, the Parakeet Auklet Aethia psittacula, which was previously considered as a monomorphic species. We compare our results with data on congeneric species to investigate the most important factors affecting the process of population differentiation in Aethini. We analyzed morphometric measurements, mitochondrial DNA control region fragment and microsatellite loci from six Parakeet Auklet colonies spanning the breeding range. Although results of microsatellite variability analysis did not reveal differences between birds from different colonies, results of control region variability and morphometric analyses testified for a slight but significant differentiation between birds from the Aleutian Islands and other parts of their range. They were significantly smaller in most linear parameters measured and had higher body condition (expressed as the scaled mass index). The results of mtDNA analysis and discrepancy between different types of genetic markers indicated that birds from Aleutian Islands and from the other parts of their breeding range probably originated from different refuges and the differentiation of mitochondrial lineages between them took place around 100 000 years ago. Our results and conclusions from the comparison with congeneric species indicated that foraging and migration patterns seem to determine population structure in small planktivorous alcids, with panmixia in highly mobile species, clear population differentiation in resident species and intermediate population differentiation in more dispersive species.

Genetic homogeneity detectable in the sedentary moray eel Gymnothorax minor based on mitochondrial DNA analysis

On the basis of traditional morphological classification, Gymnothorax minor has been misidentified as Gymnothorax reticularis in China. Because of the special ecological habits and aggressiveness of this species, little research has been performed on its population genetics. Given the general decline in offshore fishery resources, it is necessary to study the genetic characteristics of G. minor in order to protect this resource. In the present study, six different geographical populations of G. minor were collected from their distribution areas in China, and their genetic signatures were investigated for the first time based on the control region fragments. The results showed that G. minor had a very high degree of genetic diversity, and there was no genetic differentiation between these populations. However, the genetic analysis failed to reject panmixia among geographic populations of this species. The life-history characteristics of G. minor and the heterogeneity of its habitat promote the rapid growth of its populations, resulting in gene mutation accumulation and rich genetic diversity. G. minor experienced a population expansion event during the late Pleistocene, which shaped its various genetic signatures. The prolonged pelagic larval duration (PLD) of this species ensures that its leptocephali effectively avoid various physical obstacles and have the opportunity to follow ocean currents to various coastal areas of China. Finally, this moray eel exchanges genetic material with recruitment populations from other locations. All the current genetic signature results for G. minor will serve as a reference for genetic research on moray eels with similar life-history characteristics.

A Noninvasive Genetic Technique Using Guano for Identification of Corynorhinus townsendii (Townsend's Big-Eared Bat) Maternity Roosts

The use of DNA from fecal samples can allow for a better understanding of the ecology of a species without capturing and handling the animals. This is particularly useful for cryptic and elusive animals, such as bats. Being able to identify critical habitat, such as maternity roosts, for bat species in areas where they depend on abandoned mines that could be slated for closure is necessary to enact appropriate protections for such roosts. In particular, Corynorhinus townsendii commonly uses abandoned mines for maternity roosts. Further, maternity roosts are difficult to identify through visual surveys when only one or a few surveys are performed before mine closures. We have developed a method for identification of C. townsendii maternity roosts that uses fecal DNA extracted from fresh guano collected from plastic sheeting placed at a mine entrance. We provide a multiplex PCR assay to amplify a control region fragment found only in C. townsendii, as well as a Y-linked protein (DBY) to detect male C. townsendii DNA. The purpose of this study was to identify a temporal shift in the presence of male C. townsendii bats, which can be useful to identify a maternity roost. This method allows for noninvasive identification of critical habitat for this species and reduces the effort and safety risk of entering mines on the part of biologists.

Genetic diversity and population structure of Acanthopagrus schlegelii inferred from mtDNA sequences

Acanthopagrus schlegelii is a warm temperate demersal fish, which inhabits the sand–mud substrate or rocky reefs in the coastal waters of Northwest Pacific. A total of 130 samples of Acanthopagrus schlegelii from 5 localities were collected in the present study, and the genetic structure and genetic diversity was analyzed by comparing with other 3 populations based on the mitochondrial control region fragments. The haplotype diversity of A. schlegelii was high with a range from 0.8000 to 0.9803 and the nucleotide diversity was low-to-medium with a range from 0.0069 to 0.0132. No obviously genealogical branches or clusters corresponding to sampling locations were detected both in phylogenetic tree and minimum spanning tree. The AMOVA showed that most genetic variation was apportioned within the populations, and the pairwise Fst values indicated significant differentiation between north group populations and south group populations except for WN population. The results of neutrality test, mismatch distribution and Bayesian Skyline Plot (BSP) analysis indicated that A. schlegelii may have experienced a recent demographic population expansion event. We speculated that the climatic fluctuations during the Quaternary glacial had an important effect on the phylogeographic pattern of A. schlegelii populations, and the current environmental factors and fish behavior also play an important role in shaping the contemporary phylogeographic pattern of this species.

Dynamic range expansion leads to establishment of a new, genetically distinct wolf population in Central Europe

Local extinction and recolonization events can shape genetic structure of subdivided animal populations. The gray wolf (Canis lupus) was extirpated from most of Europe, but recently recolonized big part of its historical range. An exceptionally dynamic expansion of wolf population is observed in the western part of the Great European Plain. Nonetheless, genetic consequences of this process have not yet been fully understood. We aimed to assess genetic diversity of this recently established wolf population in Western Poland (WPL), determine its origin and provide novel data regarding the population genetic structure of the grey wolf in Central Europe. We utilized both spatially explicit and non-explicit Bayesian clustering approaches, as well as a model-independent, multivariate method DAPC, to infer genetic structure in large dataset (881 identified individuals) of wolf microsatellite genotypes. To put the patterns observed in studied population into a broader biogeographic context we also analyzed a mtDNA control region fragment widely used in previous studies. In comparison to a source population, we found slightly reduced allelic richness and heterozygosity in the newly recolonized areas west of the Vistula river. We discovered relatively strong west-east structuring in lowland wolves, probably reflecting founder-flush and allele surfing during range expansion, resulting in clear distinction of WPL, eastern lowland and Carpathian genetic groups. Interestingly, wolves from recently recolonized mountainous areas (Sudetes Mts, SW Poland) clustered together with lowland, but not Carpathian wolf populations. We also identified an area in Central Poland that seems to be a melting pot of western, lowland eastern and Carpathian wolves. We conclude that the process of dynamic recolonization of Central European lowlands lead to the formation of a new, genetically distinct wolf population. Together with the settlement and establishment of packs in mountains by lowland wolves and vice versa, it suggests that demographic dynamics and possibly anthropogenic barriers rather than ecological factors (e.g. natal habitat-biased dispersal patterns) shape the current wolf genetic structure in Central Europe.

DNA barcoding of sea turtles (Dermochelyidae and Cheloniidae) and its protocol using different tissues quality: implication to conservation managers

Conservation effort of sea turtles faces several challenges, e.g. habitat destruction, eggs and turtle meat consumptions, or production of souvenirs (e.g. turtle bodies). In their duties, conservation officers may find sea turtles in different condition (e.g. body fragments, eggs, pieces of meat, etc.), usually it is difficult to identify due to incomplete morphology. Therefore, the use of DNA barcoding becomes an alternative for for identification at species level, contribute taxonomic and biodiversity research. This study was conducted to develop a protocol suitable for identifying sea turtles from different tissue samples conditions using DNA barcoding. A total of 16 tissue samples in different condition (fresh, dead-body, smoked-meat) were collected. A protocol was developed to enable identification of tissue samples of different quality or condition. A 719 bp control region fragment was analyzed. The high percentage similarity was confirmed in GenBank CO1 sequence with 99%-100%. Four sea turtle species were identified among the samples, i.e. Chelonia mydas (4 samples), Lepidochelys olivacea (9 samples), Eretmochelys imbricata (2 samples) and Dermochelys coriacea (1 samples). This study was successfully amplified by using DNA target of control region and therefore, will be beneficial for conservation management of sea turtles in Indonesia.

Analysis and interpretation of mixture DNA using AS-PCR of mtDNA.

Semi-nested PCR with allele-specific (AS) primers and sequencing of mitochondrial DNA (mtDNA) were performed to analyze and interpret DNA mixtures, especially when biological materials were degraded or contained a limited amount of DNA. SNP-STR markers were available to identify the minor DNA component using AS-PCR; moreover, SNPs in mtDNA could be used when the degraded or limited amounts of DNA mixtures were not successful with SNP-STR markers. Five pairs of allele-specific primers were designed based on three SNPs (G15043A, T16362C, and T16519C). The sequence of mtDNA control region of minor components was obtained using AS-PCR and sequencing. Sequences of the amplification fragments were aligned and compared with the sequences of known suspects or databases. When this assay was used with the T16362C and T16519C SNPs, we found it to be highly sensitive for detecting small amounts of DNA (∼30 pg) and analyzing DNA mixtures of two contributors, even at an approximately 1‰ ratio of minor and major components. An exception was tests based on the SNP G15043A, which required approximately 300 pg of a 1% DNA mixture. In simulated three contributor DNA mixtures (at rate of 1:1:1), control region fragments from each contributor were detected and interpreted. AS-PCR combined with semi-nested PCR was successfully used to identify the mtDNA control region of each contributor, providing biological evidence for excluding suspects in forensic cases, especially when biological materials were degraded or had a limited amount of DNA.

No native trout on Cyprus

No native trout on Cyprus

ГЕНЕТИЧЕСКИЙ ПОЛИМОРФИЗМ ЩУКИ ESOX LUCIUS L. В УСЛОВИЯХ НЕФТЯНОГО ЗАГРЯЗНЕНИЯ

The paper describes the results of the unique analysis of nucleotide sequences of two fragments of the mitochondrial DNA (mtDNA): cytochrome c- oxidase subunite 1 gene fragment (Co-1) and a control region fragment (D-loop) for Northern pike Esox lucius from Shchuchye (No. 1-3) and Bezymyannoye lakes (the Republic of Komi). Lake district Shchuch'ye was exposed to oil pollution. Bezymyannoye lake is in better situation, that is why it is taken as a control water body without oil pollution, along with literature data and information from the GenBank (NCBI). The populations studied are characterized by a low level of genetic polymorphism, which is higher than in the lake pike of Poland, according to the literature data. For each mtDNA fragment taken for analysis there were described two haplotypes; one of the variants of a D-loop was unique. Phylogeographic analyses was performed using practical data and information of the GenBank (NCBI) for Co-1 and D-loop of pike. The results for Co-1 sequences were more interesting. Three groups of Co-1 haplotypes were revealed with definite geographic distribution. The first group combines haplotypes from Greece, Turkey, Macedonia (south philogenetic group). The second group includes the sequence variants of the E. lucius from Central Europe, and the third - the variants found in the water bodies of Northern Europe (the Scandinavian Peninsula) and haplotypes of the pike populations of lakes in the Komi Republic (northern phylogenetic line). Thus, the Komi populations are more close relation with Northern pike from the North of Europe, which shows close relationship of E. lucius to the populations in the North Europe. The mean value of the p -distances for the control region and Co-1 of mtDNA fragment between sequences of pike from the lakes of the Komi Republic and the Northern European water bodies made 0.5% and 0.3%, respectively. Differences in the level of polymorphism between samples from lakes with oil pollution and sound reservoirs at this stage of the study haven’t been revealed.

Origin and phylogeography of African savannah elephants (Loxodonta africana) in Kruger and nearby parks in southern Africa

African savannah elephants (Loxodonta africana) occur in fragmented and isolated populations across southern Africa. Transfrontier conservation efforts aim at preventing the negative effects of population fragmentation by maintaining and restoring linkages between protected areas. We sought to identify genetic linkages by comparing the elephants in Kruger National Park (South Africa) to populations in nearby countries (Botswana, Mozambique, Zambia and Zimbabwe). We used a 446 base pair mitochondrial DNA (mtDNA) control region fragment (141 individuals) and 9 nuclear DNA (nDNA) microsatellite markers (69 individuals) to investigate phylogenetic relationships and gene flow among elephant populations. The mtDNA and nDNA phylogeographic patterns were incongruent, with mtDNA patterns likely reflecting the effects of ancient female migrations, with patterns persisting due to female philopatry, and nDNA patterns likely reflecting male-mediated dispersal. Kruger elephant heterozygosity and differentiation were examined, and were not consistent with genetic isolation, a depleted gene pool or a strong founder effect. Mitochondrial DNA geographic patterns suggested that the Kruger population was founded by elephants from areas both north and south of Kruger, or has been augmented through migration from more than one geographic source. We discuss our findings in light of the need for conservation initiatives that aim at maintaining or restoring connectivity among populations. Such initiatives may provide a sustainable, self-regulating management approach for elephants in southern Africa while maintaining genetic diversity within and gene flow between Kruger and nearby regions.

Population differentiation in whiskered aukletsAethia pygmaea: do diurnal and nocturnal colonies differ in genetics, morphometry and acoustics?

Despite a great number of empirical studies, the mechanisms of population differentiation and the factors that influence this process, particularly in seabirds, remain insufficiently understood. Here we analyzed population structure in the whiskered auklet Aethia pygmaea, a previously poorly studied alcid species with unusual differentiation in colony attendance rhythms (i.e. diurnal in the Sea of Okhotsk vs nocturnal in the Bering Sea), and examined the influence of it on intraspecific differentiation. For this study, we analyzed morphometric measurements, acoustic variables, mitochondrial control region fragment and five microsatellite loci from nine whiskered auklet colonies spanning the breeding range. Previous research has shown a clinal morphometric variation in this species. We build on this analysis by adding auklets from more colonies, for the first time analyzing vocalizations from different colonies and genetic structure of this species. Our data supports a clinal variation in morphometric and acoustic characters with the largest size and the lowest call frequency in western birds, and the smallest size and highest call frequency in the east. We also found two mitochondrial lineages – whiskered auklets from colonies in the Sea of Okhotsk and the Commander Is. (Bering Sea) and from the Aleutian Is. (Bering Sea), that were presumably formed during Sangamonian interglacial period (115 000–130 000 years ago). Genetic clusters found did not reflect differences in colony attendance rhythms, suggesting that they were shaped by other factors (e.g. differences in predator pressure) and are unlikely to have participated in the formation of population structure. Colony fidelity, mobility of birds, proximity of foraging grounds and location of colonies in relation to seasonal ice pack, seem to be more likely determinants of population differentiation.

Genetic variability of brown bear (Ursus arctos L., 1758)

We perform an analysis of the diversity of the control region fragment (570 bp) and ten nuclear microsatellite loci for 36 specimens of the brown bear (Ursus arctos) from several regions of the Caucasus. Four mitochondrial haplogroups that significantly differ from each other are revealed. An assumption of reiterative brown bear colonization of the Caucasus is made. Microsatellite data analysis shows a medium level of heterozygosity and clear differentiation between Caucasian and European bears combined with a slight distinction between the Caucasian regions.