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Samples from eight water bodies in the region of Truelove and Sparbo Hardy Lowland, Devon Island (75 ° 30 N, 86 ° 00 W) yielded 70 taxa (4 Bdelloidea, 66 Monogononta) of rotifers, nineteen of which are new records for the Canadian High Arctic. 相似文献
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Markus Otto 《Pal?ontologische Zeitschrift》2005,79(4):493-505
A completely perichondrally ossified endocranium of a generalized reprsentative of the Eubrachythoraci,Beyrichosteus radiatus n. g., n. sp., is described. The specimen shows a typical platybasie skull with widely separated nasal capsules like that of the mainly Early Devonian Dolichothoraci. This is contrary to the spezialized generaTapinosteus andPholidosteus from Wildungen, being previously often regarded as model for the endocranium of coccosteomorph arthrodires. However, characters of the orbit and the nasal capsule are more similar to other Eubrachythoraci than to those of Dolichothoraci and primitive Brachythoraci. Until now, there are not enough other examples of sufficiently preserved endocrania of brachythoracid arthrodires known for a phylogenetic analysis. Nevertheless, the observations made onBeyrichosteus are questioning the assignment of the Pholidosteidae to the Coccosteomorphi. 相似文献
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Jan Bohatý 《Pal?ontologische Zeitschrift》2005,79(2):201-225
Kurzfassung Anhand von Material aus den mitteldevonischen Kalkmulden der Eifel (Rheinisches Schiefergebirge) wird eine auf Kelch- und
Armsegmenten der Cupressocrinitidae C.F.Roemer, 1854 aufliegende und deutlich getrennte Skelettschicht als Exoplacoidschicht beschrieben. Aufbau, Morphologie, Ultrastruktur
und geochemisches Signal werden vorgestellt, die Funktionsmorphologie diskutiert. Die Ausbildung der Exoplacoidschicht führt
innerhalb der bisher monotypischen Familie Cupressocrinitidae C.F.Roemer, 1854 zur Abtrennung der neuen GattungenRobustocriniles n. gen. undAbbreviatocrinites n. gen. Die GattungRobustocrinhes n. gen. undCupressocrinites
Goldfuss, 1831 besitzen eine monolamellare Exoplacoidschicht und unterscheiden sich durch weitere anatomische Merkmale von der durch
eine multilamellare Exoplacoidschicht charakterisierten GattungAbbreviatocrinites n. gen. Dieser Gattung wird neben anderen, bisherCupressocrinites untergeordneten ArtenAbbreviatocrinites geminatus n. gen. n. sp. mit besonders deutlicher multilamellarer Exoplacoidschicht zugeordnet.
相似文献
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C. M. Ann Baker 《Animal genetics》1982,13(3):199-212
It has been claimed that the origin of the South Devon breed of cattle is 'unknown' and that biochemical polymorphisms '… indicate that Gelbvieh and South Devon had a common ancestry on the Continent and are distinct from other British breeds such as Hereford, Angus and Jersey' (Kidd et al., 1974).
In fact, historical records indicate that the South Devon evolved largely from native Devon cattle and is a close relative of other English Lowland breeds such as the North Devon and Hereford. Information about crosses from other breeds makes no mention of the Gelbvieh but emphasises the contribution of Channel Island breeds, especially the Guernsey. Data for biochemical polymorphisms in the relevant breeds show agreement with the historical information and with the biogeography of the breeds involved. 相似文献
In fact, historical records indicate that the South Devon evolved largely from native Devon cattle and is a close relative of other English Lowland breeds such as the North Devon and Hereford. Information about crosses from other breeds makes no mention of the Gelbvieh but emphasises the contribution of Channel Island breeds, especially the Guernsey. Data for biochemical polymorphisms in the relevant breeds show agreement with the historical information and with the biogeography of the breeds involved. 相似文献
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Pamela Wiener Judith Alexis Smith Alyson Margaret Lewis John Arthur Woolliams John Lewis Williams 《遗传、选种与进化》2002,34(2):221-232
In this paper, we examined the effects of an 11-bp mutation within the GDF-8 gene, originally identified in Belgian Blue cattle, in the South Devon breed. The mutation was found at moderate frequency (0.37) in the South Devon population. We quantified the effects of this mutation on growth, body composition and calving traits in South Devon cattle. We found that the mutation significantly increased muscle score and calving difficulty and decreased fat depth. The mutation did not significantly affect weight at 200 and 400 days or muscle depth. Its effect on muscle score and fat depth was additive while its effect on calving difficulty was recessive. The mutation accounted for a significant proportion of the phenotypic variance in muscle score and calving difficulty. There was an economic benefit of the mutation for this data set, however, calculations were sensitive to changes in the parameter values. Additional data would be required to refine these calculations. 相似文献
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Two of the oldest known silicoflagellate-bearing sediments, lower Albian at Ocean Drilling Program Site 693 in the Weddell Sea of Antarctica and Santonian in the Devon Island sequence of the Canadian Archipelago, are re-examined with a focus on silicoflagellate genera Variramus, Cornua, and Gleserocha that lack basal rings, a feature appearing during late Santonian/early Campanian time within the genus Corbisema. The extraordinary variability of Variramus aculeifera is studied, and a new genus Gleserocha is proposed for taxa with apical structures made of three struts, but without pikes. This new genus includes previously described Variramus wisei and Cornua tapiae and new species G. harrisonii, and is here proposed as a genus transitional between Variramus and Cornua. Two unusual new species of Cornua, C. deflandrei and C. witkowskiana, are also described and a revised terminology is proposed for the skeletal components of Cornua and closely related genera. 相似文献
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Max Blake Darren Naish Greger Larson Charlotte L. King Geoff Nowell Manabu Sakamoto 《Historical Biology》2013,25(4):441-448
The alleged presence of non-native felid species in the British countryside – popularly, though in part erroneously, known as ‘British big cats’ or ‘alien big cats’ – is a long-standing and controversial topic, perennially of interest to both the mass media and amateur naturalists, and with little apparent acceptance from the technical zoological community. Nevertheless, a number of carcasses and captured live specimens have demonstrated the occasional presence within the region of escapees that potentially explain at least some ‘British big cat’ eyewitness records. We report here the existence of a probable Canada lynx, Lynx canadensis, shot in Newton Abbot, Devon, England, in or prior to 1903, and then accessioned to Bristol Museum and Art Gallery. The specimen (represented by extensive skeletal material and a stuffed taxidermy mount) is Bobcat-like in some respects but is identified as a Canada lynx on the basis of skeletal morphology with a high degree of support; attempts to extract DNA were unsuccessful. Stable strontium isotope analysis supports either a recent introduction from western Canada or long-term acclimation to the local area of Devon where it was collected. Although the specimen was undoubtedly an ‘alien’ (an escapee or release from a collection), it is significant as material evidence in demonstrating, for the first time, the presence of a wild-caught, feral, exotic felid dating to the early years of the twentieth century. 相似文献
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Use of a multivariate model using allele frequency distributions to analyse patterns of genetic differentiation among populations 总被引:3,自引:0,他引:3
Bruno Guinand 《Biological journal of the Linnean Society. Linnean Society of London》1996,58(2):173-195
Very few studies have attempted to relate the properties of some ordination techniques to classical tools of population genetics as F -statistics. A multivariate model to analyse population genetics data based on the properties of 'joint scaling' of populations and loci is developed. The design of population genetics data means that this model deals with a modified version of the classical Multiple Correspondence Analysis which is called Constant Row Total-Multiple Correspondence Analysis (CRT-MCA) and is an original tool in population genetics. Such a model allows estimates of the degree of population differentiation by studying the variability of the distribution of allele frequencies in different samples. Some clear relationships exist between some model parameters and the classical Fst statistics. The CRT-MCA also allows all the studied loci to be considered simultaneously and the role of each locus in patterns of population differentiation to be expressed. Such a multivariate approach prevents the use of any pooling strategy as is classically used in studies of hierarchical F -statistics. The relevance of the CRT-MCA model is illustrated by the analysis of population structure of 15 dogwhelk ( Nucella lapillus ) populations in south-west England. The advantages and limitations of CRT-MCA are presented. 相似文献
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