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61.
Most European migratory birds wintering in sub‐Saharan Africa have anticipated arrival to the breeding areas over the past decades. This phenological change may be ultimately caused by warming of the Northern Hemisphere via evolutionary changes or phenotypic plasticity in migration behavior. First arrival dates are negatively predicted by temperatures upon arrival to the breeding grounds. This seems puzzling, because migrants should be unable to predict weather conditions at long range. Migrants can enjoy diverse fitness benefits from early arriving. However, if weather conditions at destination cannot be predicted, early arrival can also entail severe costs. If meteorological conditions in Europe during breeding covary with those in sub‐Saharan Africa during late winter, long‐distance migrants may have a clue to predict meteorological conditions in their breeding areas while they are still in Africa and adjust their migration schedule consequently, an idea that has never been tested. We analyzed the correlation between March–April temperature anomalies (Tan) in Europe and February Tan in the Sahel and sub‐Sahel, where long‐distance migrants winter or stop‐over. Tan in Africa negatively predicted Tan in Europe, the association being particularly strong (unsigned effect size, zr>0.35) for eastern Sahel and northern and eastern Europe, where the risks of early arrival may be larger. However, the strength of the correlations between Tan in the two continents has declined during the last 25 years; thus, possibly, partly compromising adaptive mechanisms of adjustment of migration. The existence of such climatic connectivity leads to several predictions, including that positive Tan in Africa should delay arrival. Consistent with this prediction, we found that first arrival dates of seven long‐distance migratory species positively covaried with February Tan in Africa. Thus, while wintering, migrants might be able to predict meteorological conditions at the beginning of the breeding season, and phenotypically adjust migration schedules to optimally tune arrival date. 相似文献
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MARLÈNE GOUBAULT TIM P. BATCHELOR ROBERTO ROMANI ROBERT S. T. LINFORTH MATTHIAS FRITZSCHE WITTKO FRANCKE IAN C. W. HARDY 《Biological journal of the Linnean Society. Linnean Society of London》2008,94(4):837-852
The structures of volatile chemicals released by parasitic wasps in the family Bethylidae are shown to correspond to the subfamily to which the species belong. Species in the Epyrinae release skatole (3-methylindole) and species in the Bethylinae release a spiroacetal (2-methyl-1,7-dioxaspiro [5.5]undecane): these compounds are chemically very different. The enantiomeric composition of the spiroacetal differs between congeneric species. Chemical release is a discrete event under the active control of both male and female wasps. Structural differences between the mandibular glands and intramandibular glands suggest the mandibular glands to be the source of released volatiles. Real-time mass spectrometry shows that the spiroacetal is released by Goniozus nephantidis females during dyadic resource contests, with release more common during more aggressive interactions. Chemical tagging with deuterium further shows that the volatile is released by the loser of an agonistic interaction and not the winner. The function of spiroacetal and skatole release by bethylids is discussed. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 837–852. 相似文献
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ISABELA GALARDA VARASSIN JOSÉ ROBERTO TRIGO MARLIES SAZIMA 《Botanical journal of the Linnean Society. Linnean Society of London》2001,136(2):139-152
The pollination biology of four species of passionflower was studied in south-eastern Brazil, specifically the importance of chemical features of floral nectar, pigments and odours. All species required pollinators to produce fruits: P. alata was pollinated by bees, P. speciosa by hummingbirds, and P. galbana and P. mucronata by bats. Pollinators consumed nectar as a food source. The activity of vertebrate pollinators reflected resource availability: they foraged when large amounts of nectar were available and when quantitative resource predictability was greater. The nectar of the vertebrate-pollinated species was richer in cholesterol and phospholipids, and had a potassium-sodium ratio higher than 1.0. For all species, the light absorption of flowers was paralleled by the pollinators' visual spectral sensitivity. This first report on Passiflora floral volatile compounds showed that there was a greater chemical class diversity among the species pollinated by animals with an acute olfactory sense, such as bees and bats. Benzenoid alcohols were the most represented compounds. The fragrances contained compounds that occur in other plant species and in the exocrine secretions of bees. This study shows a strong association between pollinators and the attracting and rewarding features of flowers. 相似文献
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ROBERTO GAMARRA ELENA DORDA ANTONIO SCRUGLI PABLO GALÁN EMMA ORTÚÑEZ 《Botanical journal of the Linnean Society. Linnean Society of London》2007,153(2):133-140
The ultrastructure of testa seed in the genus Neotinea (Orchidaceae, Orchidinae) was examined for the first time. The morphology of the seed and of the anticlinal and periclinal walls was analysed by scanning electron microscopy. Quantitative data concerning the length and width of the seed and embryo, seed and embryo volume, free air space, and number of cells along the longitudinal axis are presented. In all species, the seeds are fusiform in shape with transverse ridges on the inner periclinal walls. This ornamentation pattern is characteristic for the genus Neotinea . It is a good diagnostic value supporting the monophyly of this genus, which has recently been proposed by several authors. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 133–140. 相似文献
65.
Influence of Flooding on Net CO2Assimilation, Growth and Stem Anatomy of Annona Species 总被引:1,自引:0,他引:1
NUNEZ-ELISEA ROBERTO; SCHAFFER BRUCE; FISHER JACK B.; COLLS ANGEL M.; CRANE JONATHAN H. 《Annals of botany》1999,84(6):771-780
A series of experiments was conducted to assess net CO2assimilationand growth responses to waterlogging of grafted and seedlingtrees in the genus Annona. Seedlings of A. glabra, A. muricataandA. squamosa L., and scions of Gefner atemoya(A. squamosaxA. cherimola Mill.), 49-11 (GefneratemoyaxA. reticulata L.), 4-5 (PriestleyatemoyaxA. reticulata), A. reticulata grafted onto either A.glabra, A. reticulata orA. squamosa rootstocks were floodedfor up to 60 d. Soil anaerobiosis occurred on the third dayof flooding. Seedlings ofA. glabra and A. muricata, and thescions 49-11, Gefner atemoya, andA. reticulata grafted onto A. glabra rootstock were consideredflood tolerant based on their ability to survive and grow inflooded conditions. Scions of the normally flood-sensitive A.reticulata, Gefner atemoya, and 49-11tolerated root waterlogging when grafted onto the flood-tolerantspecies, A. glabra. In contrast, flooding of A. squamosa seedlingsand rootstocks, and A. reticulata rootstocks greatly reducedgrowth and net CO2assimilation rates, and resulted in 2080%tree mortality. Stem anatomical responses to long-term flooding(12 continuous months) were assessed in seedlings of A. glabraand A. muricata, and trees of 49-11 grafted ontoA. glabra. Flooded trees developed hypertrophied stem lenticels,particularly in A. glabra, and enlarged xylem cells resultingin thicker stems with reduced xylem density. Flooding did notincrease air spaces in pre-existing xylem near the pith or inxylem tissue that was formed during flooding. Thus, flood tolerancedid not involve aerenchyma formation in the stem. Copyright1999 Annals of Botany Company Flood tolerance, net CO2assimilation, photosynthesis, stem anatomy, shoot growth, anaerobiosis, Annonaceae. 相似文献
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CHRISTOPHER B. ANDERSON JUAN L. CELIS‐DIEZ BARBARA J. BOND GUILLERMO MARTÍNEZ PASTUR CHRISTIAN LITTLE JUAN J. ARMESTO CLAUDIO GHERSA AMY AUSTIN TOMAS SCHLICHTER ANTONIO LARA MARTIN CARMONA ENRIQUE J. CHANETON JULIO R. GUTIERREZ RICARDO ROZZI KRISTIN VANDERBILT GUILLERMO OYARCE ROBERTO J. FERNÁNDEZ 《Austral ecology》2012,37(5):529-536
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