Links to these different parts of this bibliography and to these relevent activities may be found above in the contents List on the right hand side of this page or on the larger print version of the contents List. One such link, new and Recent Additions, provides a list of the most recent references added to the bibliography. Clicking on an author name in references listed on this web site activates a link to a list of that authors papers on threshold concepts and, where available, a link to that authors home page. New to the Threshold Concept: Where to start The Threshold Concept Framework has grown significantly since this web site was first created and this bibliography, though found useful by many lecturers, teachers and researchers familiar with the threshold concept, is now so large. It is far from obvious where such an individual starts. This section will list papers in which the authors have addressed this issue and have suggested a guide to working with the framework: Timmermans,.
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Bounded : A threshold concept will probably delineate a particular conceptual space, serving a specific and limited purpose. Discursive : meyer and Land 2 suggest that the crossing of a threshold will incorporate an enhanced and extended use of language. Reconstitutive : " Understanding a threshold concept may entail a shift in learner subjectivity, which is implied through the transformative and discursive aspects already noted. Such reconstitution is, perhaps, more likely to be recognised initially by others, and also to take place over time ( Smith. Liminality : meyer and Land 4 have likened the crossing of the pedagogic threshold to a rite of passage (drawing on the ethnographical studies of Gennep and of Turner in which a transitional or liminal space has to be traversed; in short, there. Last update: Examples of the threshold concept must be transformative and involve a traverse through a liminal space. They are likely to be characterised by many of, but not necessarily all of, the other features listed above. Using this site this site is primarily a bibliography of papers on the Threshold Concept Framework organised by topics and by authors and also includes lists of the key meyer and Land originating papers, books, overviews, critiques, theses and selected presentations. It additionally includes information on relevant activities,. Conferences on threshold concepts, special interest groups, parents awards, social networks.
Threshold Concepts may be considered to be akin to passing through a portal or conceptual gateway that opens up previously inaccessible ways of thinking about something (meyer and Land 1 ). Transformative : Once understood, a threshold concept changes the way in which the student views the discipline. Troublesome : Threshold concepts are likely to be troublesome essay for the student. Perkins 1999, 2006 has suggested that knowledge can be troublesome. When it is counter-intuitive, alien or seemingly incoherent. Irreversible : given their transformative potential, threshold concepts are also likely to be irreversible,. They are difficult to unlearn. Integrative : Threshold concepts, once learned, are likely to bring together different aspects of the subject that previously did not appear, to the student, to be related.
The idea of threshold concepts emerged from a uk national research project into the possible characteristics of strong teaching and learning environments line in the disciplines for undergraduate education (. Enhancing teaching-learning Environments in Undergraduate courses ). In pursuing this research in the field of economics, it became clear. Erik meyer and, ray land 1-7, that certain concepts were held by economists to be central to the mastery of their subject. These concepts, meyer and Land argued, could be described as threshold ones because they have certain features in common. Glynis cousin, An introduction to threshold concepts, over the past decade this concept has been embraced by many disciplines outside economics; indeed the above" is from Glynis cousins excellent the short introduction to the concept written for earth scientists. The threshold concept has been seen as a valuable tool, not only in facilitating students understanding of their subject, but in aiding the rational development of curricula in rapidly expanding arenas where there is a strong tendency to overload the curriculum (Cousin, 2008, 2006 ). This web page will describe, briefly, the characteristics of a threshold concept and list selected references to the work of those examining its value in a broad range of disciplines. Features of a threshold Concept.
wedmann, soni a; Wappler, torsten; Engel, michael. "Direct and indirect fossil records of megachilid bees from the paleogene of Central Europe (Hymenoptera: Megachilidae. Doi :.1007/s. cardinal, sophie; Danforth, Bryan. "Bees diversified in the age of eudicots". Proceedings of the royal Society B: biological Sciences. Threshold Concepts: Undergraduate teaching, postgraduate Training, Professional development and School Education. A short Introduction and a bibliography, the meyer and Land Threshold Concept.
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Retrieved 29 September 2017. In 18 genera essays of 4 tribes and 2 subfamilies in our area, 4,100 spp. In 80 genera of 11 tribes and 4 subfamilies worldwide(1) Krombein, karl. Trap-nesting wasps and bees: life histories, nests, and associates. "Wool carder bees of the genus Anthidium in the western Hemisphere (Hymenoptera: Megachilidae diversity, host plant associations, phylogeny, and biogeography". Zoological journal of the linnean Society.
Retrieved 29 September 2017. . CS1 maint: Multiple names: authors list ( link ) michener,. Bees of the world. Baltimore: Johns Hopkins University Press. "Native pollinator - wool carder bee". Phylogeny and Classification of the bee tribe megachilini (Hymenoptera: Apoidea, megachilidae with Emphasis on the genus Megachile. Proquest / University of Kansas (PhD thesis).
Manicatum scrapes the hairs from leaves to use for nesting material. 6 It is atypical because the male is larger than the female and constantly on patrol, protecting a harem by chasing and even attacking all interlopers including honey and bumble bees, its tail equipped with multiple prongs that can knife in between the segments. 7 neither the introduced Anthidium nor its American cousins are considered parasites, only territorial and at times aggressive. But some megachilidae are, including coelioxys, a kleptoparasite mostly of leafcutter bees, and Stelis, a kleptoparasite of leafcutter and mason bees. While some megachilidae are extensively studied for their commercial possibilities (or impacts others are studied by happenstance.
Chalicodoma mason bees, not commonly cultivated, are known through extended observation and writings in the last half of the 19th century by jean-Henri fabre, with his writings made further famous by his English translator Alexander teixeira de mattos (The mason bee). Chalicodoma typically uses grit rather than mud in nest construction, along with other differences. (Fabre wrote many observations, including of other Megachilidae, from his home in France; his writings inspired many future researchers and enthusiasts, from Charles Darwin to gerald Durrell.) evolution and taxonomy edit The fossil record for megachilid bees is poor, but a middle eocene dicotyledonous leaf. 8 Multiply-cut leaves and rare body fossils from the eocene of Germany and the paleocene of France suggest that Megachilinae began cutting leaves early in their evolution. 9 Phylogenetic analysis yields an age consistent with this Eocene origin for the group. 10 References edit cockerell, Theodore; Lutz, frank eugene (1 December 1921). "Some parasitic megachilid bees of the western United States" (PDF).
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In North America these cultivated bees include the introduced Megachile rotundata, ( alfalfa leafcutter bees used extensively in alfalfa pollination, and the western native and frequently raised Osmia lignaria (the orchard mason bee or blue orchard bee used in orchard pollination. Other Osmia and Megachile species are also in commercial use in North America, europe and Asia. A suite of megachilid rely on plant resins for nest construction. These "resin bees" are typically smaller than honey bees, and effective pollinators, although the hard glue-like resins can complicate management of other tunnel nesting bees. Carder bees, Anthidium, tnt are unique for using plant fibers; there are 80 to 90 species of them in North America. Ironically, a non-native is best known —. Manicatum, the european wool carder bee, was accidentally introduced to the Americas in the late '60s and has now spread across the continent. It has been described as perhaps the most widely distributed unmanaged bee species in the world. 5 like most Anthidium, rather than cutting leaves or petals,.
Most Megachilidae are native, and write a few are introduced, accidentally and intentionally; globally the number of species identified exceeds 4,000. 2 3 Thus Megachilidae represent 15 to 20 of named species of bees. The scientific name megachilidae refers to the genus Megachile, translating roughly as large lipped (Ancient Greek μέγς (mégas, big) χεῖλος (kheîlos, lip their "large lips" and strong jaws are well-suited for collection of nest building materials. Most Megachilidae build their nests in above-ground cavities; they all are solitary bees. Their nesting habits means that in some studies of bee diversity, this bee family is most likely to be the one encountered, even though the many ground nesting bees are much greater in specie numbers (70 are ground nesters). For example, in Krombeins trap-nesting survey (1967 almost all bees that nested in his offerings were megachilid species — 40 of 43 occupying bee species. (They were outnumbered in diversity by almost twice as many species of wasps (75) that utilized the nests). 4 Because they are (mostly) above-ground nesters and more commonly attracted to artificial nests, megachilid bees are also more commonly cultivated than ground nesting solitary bees. They accept nesting materials made from hollow stems, tubes, and blocks with preformed holes (nest blocks and several megachilids have become important species for agricultural / horticultural pollination.
cell. After hatching, the parasite larva kills the host larva, unless the female parasite has already done so, and then consumes the provisions. Parasitic species are of equal size or smaller than their victims. In 1921, the journal. American Museum novitates published a preliminary report on parasitic megachilid bees of the western United States. 1, diversity edit north America has an estimated 630 different megachilid species, including Megachile, osmia, anthidium, hoplitis, and Chalicodoma.
She builds a wall lost that separates the completed cell from the next one. The larva hatches from the egg and consumes the food supply. After moulting a few times, it spins a cocoon and pupates. It emerges from the nest as an adult. Males die shortly after mating, but females survive for another few weeks, during which they build new nests. Nests are often built in natural or artificial cavities. Some embed individual cells in a mass of clay or resin attached to a wall, rock surface, or plant stem. Nest cavities are often linear, for example in hollow plant stems, but not always (snail shells are used by some. Osmia, and some species readily use irregular cavities).
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A plan leaf-cutter bee showing abdominal scopa. Leaves showing cuts by a leafcutter bee. Megachilidae is a cosmopolitan family of mostly solitary bees whose pollen-carrying structure (called a scopa ) is restricted to the ventral surface of the abdomen (rather than mostly or exclusively on the hind legs as in other bee families). Megachilid genera are most commonly known as mason bees and leafcutter bees, reflecting the materials from which they build their nest cells (soil or leaves, respectively a few collect plant or animal hairs and fibers, and are called carder bees, while others use plant resins. All species feed on nectar and pollen, but a few are kleptoparasites (informally called " cuckoo bees feeding on pollen collected by other megachilid bees. Parasitic species do not possess scopae. The motion of Megachilidae in the reproductive structures of flowers is energetic and swimming-like; this agitation releases large amounts of pollen. Contents, lifecycle edit, nonparasitic species edit, lifecycle, the lifecycle of nonparasitic Megachilidae is typically that nests are built, divided into cells. Each cell receives a supply of food (pollen or a pollen/nectar mix) and an egg; after finding a suitable spot (often near where she emerged a female starts building a first cell, stocks it, and oviposits.