Demographic history, genetic structure and gene flow in a steppe-associated raptor species

Contrasting patterns of genetic diversity and lack of population structure in the lesser spotted eagle Clanga pomarina (Aves: Accipitriformes) across its breeding range

Characterizing the genetic diversity and structure of populations is essential for understanding their evolutionary history and planning species conservation. The lesser spotted eagle (Clanga pomarina) is a large migratory raptor with a relatively small breeding range concentrated in Eastern Europe. We evaluated the level of genetic diversity and population structuring by estimating the length diversity of 23 microsatellite markers in 306 individuals and sequencing 473 nucleotides from the mitochondrial pseudo-control region in 265 individuals across the distribution range. The microsatellite data suggested shallow differentiation between geographical regions and moderate genetic diversity across the range; no recent population bottlenecks were detected. Mitochondrial diversity was relatively low; however, high values were recorded at the southern edge of the distribution range. This, in combination with the star-like distribution of mitochondrial haplotypes, suggests the expansion of the European population from a single (Balkan) refugium during the late Pleistocene or early Holocene after the glacial population bottleneck. However, the Caucasian population may have survived in a separate refugium. We conclude that the lack of clear population structuring and ongoing gene flow across Europe support the treatment of the geographically restricted global population of the lesser spotted eagle as a single evolutionary and conservation unit.

Landscape heterogeneity affects diurnal raptor communities in a sub-tropical region of northwestern Himalayas, India

Raptors are highly sensitive to environmental and human-induced changes. In addition, several species of raptors exist in considerably small numbers. It is thus critical to conserve raptors and their habitats across relatively larger landscapes. We examined the diurnal raptor assemblages and seasonality in a subtropical habitat in India’s northwestern Himalayas. Quantitative data on diurnal birds of prey and their habitat features across six distinct habitat types were collected from 33 sample sites. We observed 3,434 individuals of 28 diurnal raptors belonging to two orders and three families during a two-year survey from December 2016 to November 2018. A significant variation in bird species richness and abundance was found across habitats and seasons, with farmlands and winters being the most diverse and speciose. The generalized linear model, used to determine raptor community responses, indicated that elevation and proximity to dumping sites significantly affected the raptor abundance. The non-metric multidimensional scaling (NMDS) revealed significant differences in raptor assemblages across the habitat types. The study concluded that raptors’ persistence is largely determined by their preference for favourable feeding, roosting, and nesting opportunities. The presence of protected and habitat-exclusive species validates the high conservation importance of these ecosystems, particularly the forest patches and farmlands, necessitating robust conservation and management measures in this part of northwestern Himalaya.

High genetic diversity and low differentiation retained in the European fragmented and declining Greater Spotted Eagle (Clanga clanga) population

Characterising genetic diversity and structure of populations is essential for effective conservation of threatened species. The Greater Spotted Eagle (Clanga clanga), a large and globally vulnerable raptor, is extinct or in severe decline in most of its previous range in Europe. We assessed whether the remnants of European population are genetically impoverished, and isolated from each other. We evaluated levels of genetic diversity and population structuring by sequencing mitochondrial pseudo-control region and 10 introns from various nuclear genes, and estimated length diversity in 23 microsatellite markers. The European population has expanded since the late Pleistocene, and does not exhibit signs of a recent population bottleneck. The global genetic diversity in Europe was rather similar to that detected in other similar species. Microsatellites suggested shallow but significant differentiation between the four extant populations in Estonia, Poland, Belarus and Russia (Upper Volga region) populations, but introns and mtDNA showed that only the Estonian population differed from the others. Mitochondrial diversity was highest in the northernmost Estonian population, introns suggested lower diversity in Upper Volga, microsatellites indicated equal diversity among populations. A recent bottleneck was detected in Poland, which is consistent with the observed repopulation of the region. We conclude that significant gene flow and high genetic diversity are retained in the fragmented Greater Spotted Eagle populations; there is currently no need for genetic augmentation in Europe.

Unravelling population processes over the Late Pleistocene driving contemporary genetic divergence in Palearctic buzzards

Population range expansions and contractions as a response to climate and habitat change throughout the Quaternary are known to have contributed to complex phylogenetic and population genetic events. Speciation patterns and processes in Palearctic buzzards (genus Buteo) are a long-standing example of morphological and genetic data incongruence, attributed to panmixia, habitat range shifts, contact zones, and climate change. Here we assess the systematics, phylogeography and population genetic structure of three nominal species of Palearctic buzzards, Buteo buteo (including B. b. vulpinus), B. rufinus (including B. r. cirtensis) and B. hemilasius. Phylogenetic analyses inferred from mitochondrial data recover B. hemilasius as sister to the sister clades B. r. rufinus and B. buteo complex (B. b. buteo, B. b. vulpinus, but also including B. r. cirtensis). In contrast, we find an unresolved genetic delimitation inferred from four nuclear loci, suggesting an ancestral genetic pool for all species. Time-trees suggest population contractions and expansions throughout the Pleistocene, which likely reflect habitat change and contrasting ecological niche requirements between species. Microsatellite-based extended Bayesian skyline plots reveal relatively constant population sizes for B. hemilasius, B. r. rufinus, and B. b. vulpinus, in contrast to a dramatic population expansion in B. r. cirtensis within the last 3 kya. Overall, our study illustrates how complex population processes over the Late Pleistocene have shaped the patterns of genetic divergence in Palearctic buzzards, due to the joint effects of shared ancestral polymorphisms, population expansions and contractions, with hybridization at contact zones leading to admixture and introgression.

Analysis of the Genetic Diversity and Structure of the Grey-Faced Buzzard (Butastur indicus) in Japan, Based on mtDNA

The grey-faced buzzard (Butastur indicus) is a raptor that inhabits East Asia, including Japan. Because the number of individuals has decreased by 75% over the last 40 years, this species is classified as vulnerable (VU) in Japan. In the present study, wesought to reveal the genetic structure of the Japanese grey-faced buzzard population at several breeding sites, and to assess the levels of genetic diversity within the Japanese population. We sequenced 555 bp of the mitochondrial DNA of 96 individuals sampled during the breeding season at 18 sites, and 11 individuals sampled during the winter season at one site. In total, 21 variable sites were found in the control region, and we detected 26 haplotypes among the 107 individuals. Fukuoka represented the core breeding area for grey-faced buzzards, as half of all haplotypes were detected there. Four unique haplotypes were detected in the overwintering area. The results of the network and mismatch distribution analyses indicated that the grey-faced buzzard has not experienced a genetic bottleneck in the past, but did experience recent population expansion. In addition, comparisons with other raptors revealed rich genetic diversity in the grey-faced buzzard population. Our results indicate that conservation of both breeding and wintering areas is important for the protection of the grey-faced buzzard.

Fine-scale genetic structure in a high dispersal capacity raptor, the Montagu's harrier (Circus pygargus), revealed by a set of novel microsatellite loci

The Montagu's harrier (Circus pygargus) is a semi-colonial raptor species widely but patchily distributed across the Palearctic region with recorded cases of philopatry and presence of extra-pair copulation. In order to assess Montagu's harrier spatial genetic structure and contemporary gene flow, we developed 16 new microsatellite markers using 454 pyrosequencing. Genotypes of 117 chicks sampled in a 200 × 300 km farmland area in Central Western France were analyzed to characterize genetic polymorphism at each locus and regional and fine-scale genetic structure. Fourteen markers were found polymorphic, with a number of alleles ranging from 3 to 11. The expected and observed heterozygosities ranged from 0.36 to 0.856 and from 0.35 to 0.868, respectively. A single genetic unit was found at the regional scale with higher genetic similarity observed at a small spatial scale (up to 10 km). Our results are consistent with overall large-scale juvenile and adult dispersal together with small-scale male philopatry. Cross-species amplification of this set of microsatellites makers has been successful in two closely related harrier species: the marsh harrier (Circus aeruginosus) and the Hen harrier (Circus cyaneus) for which 14 and 12 markers were polymorphic, respectively. These new microsatellite markers could be used to study the population genetic structure, contemporary gene flow and parentage analyses in these three species and to conduct microsatellite-based demographic inferences on the Montagu's harrier.

Using genetic markers to unravel the origin of birds converging towards pre-migratory sites

Identifying patterns of individual movements in spatial and temporal scales can provide valuable insight into the structure of populations and the dynamics of communities and ecosystems. Especially for migrating birds, that can face a variety of unfavorable conditions along their journey, resolving movements of individuals across their annual cycle is necessary in order to design better targeted conservation strategies. Here, we studied the movements of a small migratory falcon, the Lesser Kestrel (Falco naumanni), by genetically assigning feathers from individuals of unknown origin that concentrate in large roosts during the pre-migratory period. Our findings suggest that birds from multiple breeding populations in the Central and Eastern Mediterranean region move towards two pre-migratory sites in the Balkans, some of them detouring greatly from their expected flyways, travelling more than 500 km to reach these sites and prepare for the post-nuptial migration. By identifying the origin of individuals using the pre-migratory sites, not only we provide a better understanding of the possible impact of local threats at these sites on multiple breeding populations but also inform the design of effective conservation actions for the species.

Refugia persistence of Qinghai-Tibetan plateau by the cold-tolerant bird Tetraogallus tibetanus (Galliformes: Phasianidae)

Most of the temperate species are expected to have moved to lower altitudes during the glacial periods of the Quaternary. Here we tested this hypothesis in a cold-tolerant avian species Tibetan snowcock (Tetraogallus tibetanus) using two segments of mitochondrial gene (a 705bp Cytochrome-b; abbrev. Cyt-b and an 854 bp Control Region; abbrev. CR) and eight microsatellite loci by characterizing population differentiation and gene flow across its range. Combined (Cyt-b + CR) datasets detected several partially lineages with poor support. Microsatellite data, however, identified two distinct lineages congruent with the geographically separated western and central regions of Qinghai-Tibetan Plateau (QTP). The phylogeographic patterns that we observed might be explained by a combination of vicariance events that led to local isolation of T. tibetanus during warm periods and range expansions and population intermixing during cold periods. The results of this study add to our knowledge of population differentiation and connectivity in high altitude mountain ecosystems.