Phylogeography and post-glacial dynamics in the clonal-sexual orchid Cypripedium calceolus L.

Aim We investigated the phylogeographical history of a clonal-sexual orchid, to test the hypothesis that current patterns of genetic diversity and differentiation retain the traces of climatic fluctuations and of the species reproductive system. Location Europe, Siberia and Russian Far East. Taxon Cypripedium calceolus L. (Orchidaceae). Methods Samples (>900, from 56 locations) were genotyped at 11 nuclear microsatellite loci and plastid sequences were obtained for a subset of them. Analysis of genetic structure and approximate Bayesian computations were performed. Species distribution modelling was used to explore the effects of past climatic fluctuations on the species range. Results Analysis of genetic diversity reveals high heterozygosity and allele diversity, with no geographical trend. Three genetic clusters are identified with extant gene pools derived from ancestral demes in glacial refugia. Siberian populations exhibit different plastid haplotypes, supporting an early divergence for the Asian gene pool. Demographic results based on genetic data are compatible with an admixture event explaining differentiation in Estonia and Romania and they are consistent with past climatic dynamics inferred through species distribution modelling. Current population differentiation does not follow isolation by distance model and is compatible with a model of isolation by colonization. Main conclusions The genetic differentiation observed today in C. calceolus preserves the signature of climatic fluctuations in the historical distribution range of the species. Our findings support the central role of clonal reproduction in the reducing loss of diversity through genetic drift. The dynamics of the clonal-sexual reproduction are responsible for the persistence of ancestral variation and stability during glacial periods and post-glacial expansion.Peer reviewe

Bumblebee foraging rhythms under the midnight sun measured with radiofrequency identification

<p>Abstract</p> <p>Background</p> <p>In the permanent daylight conditions north of the Arctic circle, there is a unique opportunity for bumblebee foragers to maximise intake, and therefore colony growth, by remaining active during the entire available 24-h period. We tested the foraging rhythms of bumblebee (<it>Bombus terrestris </it>and <it>B. pascuorum</it>) colonies in northern Finland during the summer, when the sun stays above the horizon for weeks. We used fully automatic radio-frequency identification to monitor the foraging activity of more than 1,000 workers and analysed their circadian foraging rhythms.</p> <p>Results</p> <p>Foragers did not use the available 24-h foraging period but exhibited robust diurnal rhythms instead. A mean of 95.2% of the tested <it>B. terrestris </it>workers showed robust diurnal rhythms with a mean period of 23.8 h. Foraging activity took place mainly between 08:00 and 23:00, with only low or almost no activity during the rest of the day. Activity levels increased steadily during the morning, reached a maximum around midday and decreased again during late afternoon and early evening. Foraging patterns of native <it>B. pascuorum </it>followed the same temporal organisation, with the foraging activity being restricted to the period between 06:00 and 22:00.</p> <p>Conclusions</p> <p>The results of the present study indicate that the circadian clock of the foragers must have been entrained by some external cue, the most prominent being daily cycles in light intensity and temperature. Daily fluctuations in the spectral composition of light, especially in the UV range, could also be responsible for synchronising the circadian clock of the foragers under continuous daylight conditions.</p

Shifts in mycorrhiza and microbial activity along an oroarctic altitudinal gradient in Northern Fennoscandia

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The irrelevance of stated plans in predicting farm successions in Finland

This study estimates the value of farmers stated succession plans in predicting revealed succession decisions. The stated succession plan exists when a farmer answers in a survey questionnaire that the farm is going to be transferred to a new entrant within a five year period. The succession is revealed when the farm is transferred to a successor. The stated and revealed behaviour is estimated as a recursive Binomial-Probit- Model, which accounts for censoring of the decision variables and controls for a potential correlation between the estimating equations. The results suggest that the succession plans, as stated by elderly farmers in the questionnaires, do not provide information that is significant and valuable in predicting the true, revealed successions, once certain farm and farmer characteristics are controlled for

The irrelevance of stated plans in predicting farm successions in Finland

Suomalaisen maatalouden rakenne on muuttunut nopeasti viimeisen vuosikymmenen aikana; maatilojen määrä on vähentynyt ja keskikoko kasvanut. Samaan aikaan tehtyjen sukupolvenvaihdosten määrä on vähentynyt. Maatalouden rakennekehityksen ennustamiseksi viljelijöiltä onkin viime aikoina alettu toistuvasti kysellä heidän sukupolvenvaihdossuunnitelmiaan. Aikaisempien tutkimusten perusteella viljelijöiden sukupolvenvaihdossuunnitelmat muuttuvat kuitenkin ajan myötä. Tässä tutkimuksessa verrataan viljelijöiden sukupolvenvaihdosaikomuksia koskevia kyselyvastauksia ja toteutunutta kehitystä toisiinsa. Tavoitteena on selvittää, voidaanko viljelijäkyselyjen perusteella ylipäätään tuottaa tilastoista ja viljelijöiden ikäjakaumista saatavan tiedon lisäksi sellaista tietoa, joka auttaisi ennustamaan sukupolvenvaihdosten määrää ja maatalouden rakennekehityksen nopeutta yhä tarkemmin. Tutkimusaineistona käytettiin kirjanpitotila-aineistoa vuosilta 1996 2001 sekä näille tiloille vuosina 1996 1997 tehtyä kyselyä. Kyselyssä selvitettiin, aiottiinko tilalla tehdä sukupolvenvaihdos seuraavan viiden vuoden aikana. Tarkastelussa oli mukana 97 tilaa, jotka vastasivat kyselyyn 1996 1997 ja jotka olivat mukana kirjanpitotila- aineistossa vuoteen 2001 asti. Tarkastelu perustui rekursiiviseen probit-analyysiin. Tulosten perusteella viljelijäkyselyjen vastausten perusteella ei voida ennustaa toteutuneita sukupolvenvaihdoksia. Yhtenä syynä tähän on, että sukupolvenvaihdossuunnitelmat muuttuvat ajan myötä. Lisäksi viljelijäkyselyt on yleensä suunnattu ikääntyville viljelijöille eikä niissä oteta huomioon mahdollisen jatkajan odotuksia tai mielipiteitä.This study estimates the value of farmers stated succession plans in predicting revealed succession decisions. The stated succession plan exists when a farmer answers in a survey questionnaire that the farm is going to be transferred to a new entrant within a five year period. The succession is revealed when the farm is transferred to a successor. The stated and revealed behaviour is estimated as a recursive Binomial-Probit- Model, which accounts for censoring of the decision variables and controls for a potential correlation between the estimating equations. The results suggest that the succession plans, as stated by elderly farmers in the questionnaires, do not provide information that is significant and valuable in predicting the true, revealed successions, once certain farm and farmer characteristics are controlled for.v2010okKyselyvastausten käyttökelpoisuus sukupolvenvaihdosten ennustamisess