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Die oligolektische Sandbiene Andrena florea und die Rote Zaunrübe Bryoia dioica – Schnittstelle zweier spezialisierter Fortpflanzungssysteme [The oligolectic andrenid bee Andrena florea and the White Bryony Bryoia dioica – interface of two specialised reproduction systems.]
... Here, we report observations on the behaviour of males and females of the solitary digger bee, Andrena florea Fabricius (Andrenidae), an oligolectic species whose females collect pollen almost exclusively from the delicate white blossoms of bryony (Bryonia, Cucurbitaceae), a genus of dioecious plants (Westrich, 1989;Schröder and Lunau, 2001) and -though more rarely-from species of Ecballium, the sister genus to Bryonia (Dukas, 1987). ...
... The relationship of A. florea and plants of the genus Bryonia is probably as old as the long history of Bryonia in Eurasia (L. Larkin, personal communication quoted in Volz and Renner, 2008) and there is great overlap between ranges of these bees and their host plants (Westrich, 1989;Schröder and Lunau, 2001). This strict relationship is thus likely to have influenced the behaviour of the bees, not only in terms of foraging behaviour by females (e.g. ...
... Males were only observed to search for females exclusively on B. dioica flowers, according to the prediction that, at low female (nest) density, ma-les of oligolectic bees would use resource-based, rendez-vous sites (Paxton, 2005). Female pollen specialization in this species can be visible even in the adjustment of the female bee foraging behaviour at a daily scale: females collect pollen considerably earlier in the morning (peak at 11:00-12:00) than their collection of nectar (peak at 14:00-15:00), i.e. when pollen presentation by the staminate flowers is also peaking (Schröder and Lunau, 2001). Previous observation on foraging behaviour by females of this species reported similar daily curves, with pollen collection peaking even earlier, at 10:00-11:00 (Schröder and Lunau, 2001). ...
Females of the solitary digger bee Andrena florea Fabricius, 1793 (Hymenoptera, Andrenidae) nest in aggregations and collect pollen almost exclusively on dioecious plants of the genus Bryonia, making this species a good model to study the relationship between nest density, male density, male behaviour and female lecty. At a study site in the valley of the river Serio, in Italy, an aggregation of this bee showed low density of randomly distributed nests and was closely surrounded by B. dioica plants. Female nectar foraging and male feeding and mate–searching activity, confined to the host plants, peaked at similar hours across the day, while female pollen foraging peaked earlier. Males fed on plants of both sexes but seemed to perch waiting for females more frequently on male B. dioica leaves. Individual males more often visited only one of the male plants, for up to four days; here they did not interact aggressively with conspecifics, suggesting
scramble competition in resource–based home ranges and not territoriality. These findings are preliminarily in accordance with the predicted resource–based rendez–vous sites at low nest density for oligolectic bees and the predicted occurrence of scramble competition in case of high male density. Additionally, males would maximize their mating opportunity by mainly perching on male plants, the only source of the most limited
resource for females (pollen).
... Changes in the distribution ranges of Bryonia L. species have mostly been caused by human activity, as these plants have been used as medicines and ornamentals for more than two millennia (RENNER & SCHAEFER 2008). At the same time, researchers in western Europe have observed a gradual increase in the number of localities of a previously very rare bee species, Andrena florea FABRICIUS, 1793(SCHRÖDER & LUNAU 2001, AYASSE et al. 2015, VENNE 2015, which they consider to be linked with the spread of its forage plant, Bryonia dioica. Such an increase has also taken place in Poland. ...
... RATYŃSKA et al. (2010) regard them as a very expansive, xenospontaneous community, spreading especially along river valleys. The expansion of Bryonia dioica has also been confirmed by a number of authors from Germany (SCHRÖDER & LUNAU 2001, CADOUM & DIDIER 2008, VENNE 2015, AYASSE et al. 2015 and Austria (ZETTEL et al. 2013). ...
Although research into alien species usually focuses on their negative aspects associated with their penetration into native ecosystems, their influence is much more complicated. This study investigated the pollinators of Bryonia dioica , an invasive climber in the temperate zone. Flowers of this plant in two cities in western Poland (Bydgoszcz and Poznań) were visited by 27 bee species, the most frequent ones being Apis mellifera and Andrena florea . Until recently, the latter was regarded as rare and threatened in Poland. Our results indicate that the spread of Bryonia dioica into urban areas has enabled large and stable populations of Andrena florea to flourish there. This study investigated the daily and seasonal dynamics of its activity. A positive relationship was found between the spread of Bryonia dioica and the presence of its obligatory pollinator Andrena florea . Alien plant species are thus not only an additional source of food for local pollinators but also may favour the occurrence of otherwise rare species with specific food requirements, such as A. florea.
... In terms of genome ploidy, B. alba, B. dioica, B. multiflora, and B. syriaca are diploid (2n = 2x = 20), whereas B. cretica is hexaploid (2n = 6x = 60) (Volz & Renner, 2008). All species of Bryonia are pollinated by pollen-and nectargathering bees, and the fruits are berries that are dispersed by birds (Kugler, 1981; Westrich, 1989; Schrö - der & Lunau, 2001). One of the pollinators of Bryonia species is the Bryonia pollen specialist Andrena florea, which has a foraging range of up to 1 km (Edwards & Williams, 2004). ...
Genetic crosses between the dioecious Bryonia dioica (Cucurbitaceae) and the monoecious B. alba in 1903 provided the first clear evidence for Mendelian inheritance of dioecy and made B. dioica the first organism for which XY sex-determination was experimentally proven. Applying molecular tools to this system, we developed a sex-linked sequence-characterized amplified region (SCAR) marker for B. dioica and sequenced it for individuals representing the full geographic range of the species from Scotland to North Africa. For comparison, we also sequenced this marker for representatives of the dioecious B. cretica, B. multiflora and B. syriaca, and monoecious B. alba. In no case did any individual, male or female, yield more than two haplotypes. In northern Europe, we found strong linkage between our marker and sex, with all Y-sequences being identical to each other. In southern Europe, however, the linkage between our marker and sex was weak, with recombination detected within both the X- and the Y-homologues. Population genetic analyses suggest that the SCAR marker experienced different evolutionary pressures in northern and southern Europe. These findings fit with phylogenetic evidence that the XY system in Bryonia is labile and suggest that the genus may be a good system in which to study the early steps of sex chromosome evolution.
Zusammenfassung: Das Farbensehen von Bienen unterscheidet sich von dem des Menschen dadurch, dass Bienen ultraviolettes Licht sehen können, aber unempfi ndlich für rotes Licht sind. Blumenfarben, die in Anpassung an Bienen als Bestäuber entstanden sind, sind nicht für das Farben-sehen des Menschen, sondern für das der Bienen gemacht. Für Bienen ist es bei der Orientierung an Blütenfarben zunächst wichtig, Blüten aus der Entfernung zu detektieren; das geschieht farbenblind vermittelt durch einen Grünkontrast der Blütenfarbe zum Hintergrund. Erst beim Näherkommen wird der Farbkontrast zum Hintergrund wichtig für Bienen. Beim Suchen einer erlernten Blütenfarbe orientieren sich Bienen vorwiegend nach dem Farbton, beim Finden neuer Blüten orientieren sich naive Bienen angeborenermaßen nach der spektralen Reinheit. Blütenfarbmuster weisen den Bie-nen den Weg zur Blütenbelohnung aus Nektar oder Pollen. Farbänderungen der Blütenkrone, der Blütenmale oder der Staubgefäße enthalten Informationen über die Belohnungsmenge. Spektrofoto-metrische Messungen von sehr kleinen Farbmusterkomponenten, Staubgefäßen oder gar einzelnen Pollenkörnern sind wegen der geringen Größe und den ungewöhnlichen Oberfl ächeneigenschaften meist nicht möglich. Mittels Falschfarbenfotografi e werden solche für Bienen sichtbare, für den Menschen unauffällige Blütensignale visualisiert. Bei der Falschfarbenfotografi e werden Ultraviolett als Blau, Blau als Grün und Grün als Rot dargestellt und Rot verworfen, sodass ein für Menschen gut interpretierbares Bild in Falschfarben entsteht, dass alle für Bienen sichtbaren Farbkomponenten enthält, aber keine Informationen, die nicht relevant sind. Durch Falschfarbenfotografi e konnte der Nachweis erbracht werden, dass für den Menschen farblich ähnliche Vogel-und Bienenblumen für Bienen gut unterscheidbar sein können, dass Glanzmuster auf Blüten als Nektarimitation dienen können, Blütenmale durch farbliche Einrahmungen für Bienen besser sichtbar sein können und dass Farb-und UV-Muster auf Blüten durch unterschiedliche Pigmente erzeugt werden. Schlüsselwörter: Blütenfarbe, Blütenfarbmuster, Bienen, Apidae, Farbensehen Summary: Colour vision in bees is different from that in humans, since bees are sensitive to ultraviolet light, but insensitive to red light. Flower colours that evolved in adaptation to bees as pollinators do not fi t colour vision in humans rather than colour vision in bees. For bees, the detection of fl owers from a distance is achieved by green contrast between fl ower and background colour, a colour-blind visual task. At close range the colour contrast against the background is important for bees. If searching for a learnt fl ower colour bees mainly orientate by means of colour hue, if searching for new fl owers naïve bees innately orientate by means of spectral purity. Floral colour patterns guide bees towards the fl oral reward, nectar or pollen. Colour changes of fl oral guides or stamens provide information about the amount of reward. Spectrophotometric measurements of very small coloured structures of fl owers like single pollen grains are not possible due to its small size and its rough surface properties. Using false colour photography small structures on fl owers that are visible for bees can be visualized. False colour photography visualizes ultraviolet as blue, blue as green, and green as red, while red is discarded. By this means, a well interpretable false colour photo can be produced that contains all relevant colour information for bees, but no additional information. By means of false colour photography evidence could be provided that bird-pollinated and bee-2 KLAUS LUNAU
The impact of coevolutionary interaction between species on adaptive radiation processes is analysed with reference to pollination biology case studies. Occasional colonization of archipelagos can bring together coevolving partners and cause coradiation of the colonizing species, e.g. the drepanidids and the lobelioids on Hawaii. Permanent reciprocal selective pressure between pairs of coevolving species can lead to a coevolutionary race and rapid evolutionary change. This is exemplified by spurred flowers and long-tongued flower-visitors. The geographic patterning of diffuse coevolution systems can lead to dramatic changes in species interactions. In different populations, interaction between pollinating and seed-parasitizing Greya moths and their host plants varies from mutualism to commensalism and antagonism, depending on the presence of copollinators. Asymmetrical coevolution between angiosperms and oligolectic flower-visitors may facilitate rapid reproductive isolation of populations following a food-plant switch, if the oligoleges use their specific food plants as the rendezvous sites. Diffuse coevolution between angiosperm species and pollinating insects may cause frequent convergent evolution of floral traits such as nectar reward instead of pollen reward, floral guides, zygomorphic flowers, or mimicry of pollen signals, since the multiple plant species experience similar selective pressures via the coevolving partners. Patterns of angiosperm adaptive radiation are highlighted in the context of coevolution with pollinators.
Correns's 1903 (Berichte der Deutschen Botanischen Gesellschaft 21: 133-147) crosses between a monoecious and a dioecious species of Bryonia revealed the simple Mendelian inheritance of dioecy and provided the first instance of an XY sex determination system in any organism. Bryonia ranges from the Canary Islands to Central Asia and comprises seven dioecious and three monoecious species; its closest relative, Ecballium elaterium, has dioecious and monoecious populations. We used chloroplast (cp) and nuclear (nr) gene phylogenies to infer sexual system evolution in Bryonia. We also tested for associations between sexual system and ploidy level, based on published and original chromosome counts. Conflicts between cp and nr topologies imply that the dioecious hexaploid B. cretica arose from hybridization(s), probably involving the dioecious diploids B. dioica, B. syriaca, and/or B. multiflora. A tetraploid dioecious endemic on Corsica and Sardinia probably originated from B. dioica via autopolyploidy. While the cp phylogeny resolves few species relationships, the nr tree implies at least two evolutionary changes in sexual system. There is no correlation between sexual system and ploidy level. Molecular clocks suggest that the deepest divergence, between a species on the Canary Islands and the ancestor of all remaining species, occurred ca. 10 million years ago.
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