Sex− and species−biased gene flow in a spotted eagle hybrid zone

<p>Abstract</p> <p>Background</p> <p>Recent theoretical and empirical work points toward a significant role for sex-chromosome linked genes in the evolution of traits that induce reproductive isolation and for traits that evolve under influence of sexual selection. Empirical studies including recently diverged (Pleistocene), short-lived avian species pairs with short generation times have found that introgression occurs on the autosomes but not on the Z-chromosome. Here we study genetic differentiation and gene flow in the long-lived greater spotted eagle (<it>Aquila clanga</it>) and lesser spotted eagle (<it>A. pomarina</it>), two species with comparatively long generation times.</p> <p>Results</p> <p>Our data suggest that there is a directional bias in migration rates between hybridizing spotted eagles in eastern Europe. We find that a model including post divergence gene flow fits our data best for both autosomal and Z-chromosome linked loci but, for the Z-chromosome, the rate is reduced in the direction from <it>A. pomarina </it>to <it>A. clanga</it>.</p> <p>Conclusions</p> <p>The fact that some introgression still occurs on the Z-chromosome between these species suggests that the differentiation process is in a more premature phase in our study system than in previously studied avian species pairs and that could be explained by a shorter divergence time and/or a longer average generation time in the spotted eagles. The results are in agreement with field observations and provide further insight into the role of sex-linked loci for the build-up of barriers to gene flow among diverging populations and species.</p

Insertion-deletion polymorphisms (indels) as genetic markers in natural populations

<p>Abstract</p> <p>Background</p> <p>We introduce the use of short insertion-deletion polymorphisms (indels) for genetic analysis of natural populations.</p> <p>Results</p> <p>Sequence reads from light shot-gun sequencing efforts of different dog breeds were aligned to the dog genome reference sequence and gaps corresponding to indels were identified. One hundred candidate markers (4-bp indels) were selected and genotyped in unrelated dogs (n = 7) and wolves (n = 18). Eighty-one and 76 out of 94 could be validated as polymorphic loci in the respective sample. Mean indel heterozygosity in a diverse set of wolves was 19%, and 74% of the loci had a minor allele frequency of >10%. Indels found to be polymorphic in wolves were subsequently genotyped in a highly bottlenecked Scandinavian wolf population. Fifty-one loci turned out to be polymorphic, showing their utility even in a population with low genetic diversity. In this population, individual heterozygosity measured at indel and microsatellite loci were highly correlated.</p> <p>Conclusion</p> <p>With an increasing amount of sequence information gathered from non-model organisms, we suggest that indels will come to form an important source of genetic markers, easy and cheap to genotype, for studies of natural populations.</p

Väike-konnakotka elupaigavaliku pikaajalised muutused looduskaitseliste piirangute ja majandussoovituste kontekstis : projekti nr 17019 lõpparuanne

Väike-konnakotkas on Eestis I kategooria kaitsealune linnuliik. Ta pesitseb küpsetes metsades, mis on ohustatud raietööde poolt, ning tema eelistatud toitumisalaks on rohumaad, mis võsastumise vältimiseks nõuavad väheintensiivset majandamist. Seega on väike-konnakotka asurkonna seisund erineval moel sõltuv inimtegevusest ning tema tulevik sõltub sellest, mil määral on tema elupaigad kaitstud ning kuidas ta suudab inimmõjuga kohaneda. Oluline on teada, kui kiired ning ulatuslikud on sellised elupaigamuutused võrreldes antropogeensete maastikumuutustega. Ühtlasi tuleb selgitada, kas suureneva inimmõju ja muutuva elupaigavaliku kontekstis on elupaikade kaitse meetmed endiselt optimaalsed. Eesti väike-konnakotkaste elupaiku on varem põhjalikult kirjeldatud kolmel korral. Esmakordselt tehti seda 1990. aastal ning siis kogutud teadmiste valguses määratleti praegugi looduskaitseseaduses kehtivad looduskaitselised piirangud maaomanikele. Hiljem on elupaiku kirjeldatud 2000. ning 2010. aastal ning neid teadmisi on kasutatud jooksvalt väike-konnakotka kaitse tegevuskavade koostamisel. Käesoleva töö esimeses osas kirjeldati elupaikade omadusi 2020. aastal üle Eesti paiknevate väikekonnakotkapesade ümbruses nii pesapaiga kui maastiku tasandil. Järgiti varem kasutatud metoodikat, mis võimaldas tulemuste kõrvutamist varasemate töödega ning analüüsida kolme aastakümne jooksul (1990–2020) toimunud muutusi väike-konnakotka elupaikades. Elupaigamuutused võivad toimuda vanade pesitsusterritooriumide hülgamise ja uute asustamise teel, aga ka konkreetsetel pesitsusterritooriumidel paaride kohanemise või lindude asendumisega. Hüpoteesi muutustest konkreetsetel pesitsusterritooriumidel kontrolliti uuringu teises osas. Selleks kirjeldati aastatel 2010–2020. asustatud olnud väikekonnakotka pesapaigad Loode-Tartumaa uurimisalal ning koondati elupaigakirjeldused varasemast perioodist (1987–2009). See analüüs on osaks II prioriteediklassiga tegevusest „Pikaajalise populatsiooniuuringu jätkamine“ 2018. a kinnitatud väike-konnakotka kaitse tegevuskavas.Finantseerija: Keskkonnainvesteeringute Kesku

Migration patterns of the Osprey Pandion haliaetus on the Eastern European–East African flyway

We analysed migration strategies of the Osprey Pandion haliaetus on the poorly studied Eastern European– East African flyway. Four adult birds were equipped with GPS-based satellite-transmitters or data-loggers in their breeding sites in Estonia (north-eastern Europe) and tracked to their wintering grounds in Africa and back, during up to six migration cycles. Departure times, migration routes, as well as wintering and stopover sites varied remarkably between individuals but not much between years. Stopovers (2–30 days) were made mostly in Europe and less in the Middle East (Turkey) and north-eastern Africa (Egypt). The Ospreys did not avoid flying long distances over the sea, and the sea was crossed four times during the night. The current study adds to current knowledge on Osprey migration and should help to concentrate actions on protecting important flyways and stopover locations.Keywords: migration, Osprey, raptor, stopover, telemetr

Natural margins of arable fields support small mammal populations

Biodiversity conservation strategies in agricultural landscape often recommend keeping margins of arable fields in natural conditions. However, effect of such management method has been estimated only in limited number of taxa and quantitative analysis on the optimal width of such 'green margins' is seldom conducted. We analysed the potential effect of such management method on small mammals, which form an important part in the food chain and thus belong to keystones of the ecosystem. We measured abundance of three rodent species at ecotones between forests and three types of open agricultural biotopes (grasslands, rapeseed fields and cereal fields). The maximum density of rodents was found at the forest/grassland ecotone. Here the highest densities of the Yellow-necked Mouse Apodemus flavicollis and Striped Field Mouse A. agrarius were detected. The positive edge-effect did not exceed ten meters. Also the highest density of forest-dwelling Bank Voles Myodes glareolus was recorded next to grasslands, but the abundance of this species increased towards forest interior. Rodent densities at forest/arable field ecotones were 3-5 times lower than on the edges of grassland. Summarizing, our results support maintaining narrow grasslands at margins of crop fields. Such management practice would strengthen natural communities at ecotones, but also in adjacent open land and forests.peerReviewe

Greenish Warbler (Phylloscopus trochiloides viridanus): An overlooked indicator of old-growth forest?

Effective bioindicators of old-growth forest are important for conservation. The Greenish Warbler (Phylloscopus trochiloides viridanus), a forest-dwelling passerine, has been recorded in old-growth forests; however, its precise habitat preferences are poorly studied. We used opportunistic observations collected by citizen scientists and stand descriptions from a forestry database to analyse its habitat preferences in Estonia, with a focus on the characteristics of old-growth forests. The Greenish Warbler preferred productive spruce and black alder stands but also favoured rare broad-leaved stands. Forest stands were older, less drained and contained more standing and fallen dead trees in warbler sites than in control sites. Positive effects of stand age and soil fertility exhibited the highest average relative importance in generalized linear models, drainage was of intermediate importance and the occurrence of dead wood was least important. The terrain at warbler sites was also more often uneven than that at control sites. The preference for old-growth forests observed in our study makes the Greenish Warbler, despite occupying various forest stands suggestive of plasticity, a good candidate for inclusion in a suite of old-growth forest indicators

Pollen richness : a reflection of vegetation diversity or pollen-specific parameters?

Our study aims to increase the understanding about the impacts of potential drivers of pollen richness by using a pollen-vegetation modelling approach. We used the Sutton-Prentice dispersal model implemented in the HUMPOL software suite to explore the effects of factors commonly associated with pollen richness: vegetation diversity (plant richness and evenness), land-cover characteristics (patch richness, evenness and size, and basin size) and pollen-related parameters (productivity and fall speed). The impact of the factors was tested using modelling scenarios involving all combinations of the included factors and their values. All tested factors had a statistically significant impact on modelled pollen richness. Pollen-type based plant richness was the dominant determinant of pollen richness; however, pollen productivity became co-dominant at higher plant richness levels, effectively limiting the detection of species with low pollen productivity. The fall speed of pollen and sedimentary basin size had moderate impact, but gained importance in simulations with elevated plant richness. In patchy land-cover, patch richness was the most significant determinant of pollen richness, while patch evenness and size were the least important factors. Our modelling approach provides insights into the significance of common factors in determining pollen richness and its connection to plant diversity, as well as a theoretical basis for understanding the substantial variation among earlier empirical pollen-plant richness studies. The estimation of plant richness from pollen richness in past vegetation diversity studies could be improved by the separation of taxa with low and high pollen productivity and an awareness of the pollen source area