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51.
The systematics of the order Tubulidentata is poorly known. Its phylogeny has never been thoroughly analysed and only a single review has ever been performed, which was over 30 years ago. This situation has hampered palaeoecological and palaeobiogeographical studies of these Neogene mammals. The present revision of the Orycteropodidae deals with the phylogeny and systematics of all African and Eurasian species over the last 20 Myr. The first comprehensive cladistic analysis of the family is presented here. The results of this analysis, based on 39 coded morphological characters, supplemented by non‐coded features taken from all over the skeleton, was used to reconstruct the phylogeny of the order Tubulidentata. Two distinct lineages within the genus Orycteropus are recognized and characterized. The new genus Amphiorycteropus is subsequently created, in order to harmonize taxonomy and phylogeny. The fossil genera Leptorycteropus and Myorycteropus are validated, bringing the number of genera in the order Tubulidentata to four. Moreover, within the family Orycteropodidae, the number of confirmed species is now 14. The outcome of this study allows us to propose a consistent palaeobiogeographical scenario for aardvarks. Finally, this revision represents the most comprehensive work on the evolutionary history of the order Tubulidentata to date, and provides a new framework for future studies. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 649–702.  相似文献   
52.
Seedlings of the self-fertilizing species Lactuca scariola L. grown continuously in 8 h days did not flower even one year from sowing. Seedlings grown in 16 h days uatil flower buds appeared 96 days after germination were either transferred to 8 h days or treated weekly with gibberellic acid (GA3), abscisic acid (ABA) or chlormequat (CCC) and retained, together with untreated control plants, in 16 h days. Each growth regulator caused characteristic morphological changes in the treated plants. All these plants flowered and produced seeds but the seeds showed distinct differences in weight, in their time to germination and in the seedlings which they produced. Germination and seedling characters depended on the light regime during germination as well as on the chemical applied to the parent plant and the rate of application. The parental treatment also affected the shape and size of the seedlings on a given day after germination, and certain treatments of the parent plant (transfer from long to short days and treatment with CCC in long days) advanced the flowering date of the seedlings. The gibberellin level in the seeds was raised, in increasing order, by treatment of the parent plant with 100 mg/1 GA3, transfer from long to short days, 10 mg/1 GA3, and 5000 mg/l CCC. It is suggested that the effect of day length on plant performance is mediated by the level of growth regelating substances within the plant and that the behaviour of seeds can be modified by the parental environment via the accumulation of different levels of certain growth factors in the seeds. A rise of one growth substance in the parent plant can result in the accumulation of a different one in the seeds.  相似文献   
53.
Abstract: Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), is endemic in free-ranging white-tailed deer (Odocoileus virginianus) in 5 counties (Alcona, Alpena, Montmorency, Oscoda, and Presque Isle) in the northeastern Lower Peninsula of Michigan, USA. The presence of a wildlife reservoir of tuberculosis in Michigan and the incidence of bTB in cattle (Bos taurus) resulted in Michigan losing its bTB accredited-free status. Subsequent wildlife surveillance programs identified relatively high disease prevalence in coyotes (Canis latrans), generating interest in their potential to serve as a sentinel species to detect bTB prevalence in white-tailed deer. Our goal was to develop an empirical basis for generating hypotheses about the spatial epidemiology of bTB infection in coyotes for future surveillance, management, and modeling efforts. Though variation in coyote home-range size may confound attempts to spatially correlate the incidence of disease in the sentinel and host species at a fine scale, overlap zones (OZs) between adjacent coyote home ranges may be the appropriate sample unit for spatially correlating disease prevalence in coyotes and white-tailed deer. Because overlapping home ranges are generally configured around resource rich (e.g., small mammals and white-tailed deer) timber management patches, the OZ concentrates spatial interaction between adjacent groups in a relatively small area. Furthermore, there is a direct relationship between interaction probabilities and the spatial dispersion of those patches. The latter finding provides a useful metric to incorporate into future efforts to develop spatially explicit models of bTB dynamics. Modeling efforts can then be used as a foundation to predict the epidemiological ramifications of alterations in intensively managed forested landscapes. (JOURNAL OF WILDLIFE MANAGEMENT 71(5):1545-1554; 2007)  相似文献   
54.
The Triassic fossil record points to the monophyly of the Pectinoidea (scallops), all members of which have a triangular resilium with a nonmineralized medial core that functions below the hinge line. The elastic properties of this resilium in extant taxa predict that the initial adaptation of the Pectinoidea was to swimming. This is indeed corroborated by the shell form of Pernopecten , the earliest known pectinoidean genus, which ranged from late Devonian to earliest Triassic. The new family Entolioididae, a largely Triassic group, provides the missing link between the Pernopectinidae and the families Propeamussiidae, Entoliidae, and Pectinidae, all of which originated by the Middle Triassic and survive to the present day. A new Triassic genus Filamussium shows that the Propeamussiidae originated from the Entolioididae, not directly from the Pernopectinidae as previously supposed. Evidence from morphology, the fossil record, and molecular genetics indicates that the family Spondylidae originated in the Middle Jurassic from an ancestor within the Pectinidae, possibly the genus Spondylopecten , which was already present in the Late Triassic. Journal compilation © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 148 , 313–342. No claim to original US government works  相似文献   
55.
以澳洲杨的胚珠及其种子为材料,运用光学显微镜和电镜扫描的方法对其从胚珠发生直到种子成熟的个体发育过程和结构进行观察,同时与鸭脚西番莲的种子附属结构的发育过程进行对比研究。结果表明:(1)澳洲杨的珠孔类型为外珠孔类型,种子附属结构起源于珠孔而非珠柄,其为种阜,而非假种皮。(2)鸭脚西番莲的珠孔类型为内珠孔类型,种子附属结构起源于珠柄,并且最终将珠孔包被,其为真正的假种皮结构。通过种阜与假种皮的不同个体发育过程,建立了大戟科种阜与假种皮的不同发育模式,并对种子附属结构的生物学功能及其暗示的不同植物进化路径进行了讨论。  相似文献   
56.
This study examined the transcultural robustness of a screening instrument for hypomania, the Hypomania Checklist-32, first revised version (HCL-32 R1). It was carried out in 2606 patients from twelve countries in five geographic regions (Northern, Southern and Eastern Europe, South America and East Asia). In addition, GAMIAN Europe contributed data from its members. Exploratory and confirmatory factor analyses were used to examine the transregional stability of the measurement properties of the HCL-32 R1, including the influence of sex and age as covariates. Across cultures, a two-factor structure was confirmed: the first factor (F1) reflected the more positive aspects of hypomania (being more active, elated, self-confident, and cogni-tively enhanced); the second factor (F2) reflected the more negative aspects (being irritable, impulsive, careless, more substance use). The measurement properties of the HCL-32 R1 were largely invariant across cultures. Only few items showed transcultural differences in their relation to hypomania as measured by the test. F2 was higher among men and in more severe manic syndromes; F1 was highest in North and East Europe and lowest in South America. The scores decreased slightly with age. The frequency of the 32 items showed remarkable similarities across geographic areas, with two excep-tions: South Europeans had lower symptom frequencies in general and East Europeans higher rates of substance use. These findings support the interna-tional applicability of the HCL-32 R1 as a screening instrument for hypomania.  相似文献   
57.
SUMMARY. 1. In Laurel Creek Reservoir. Ontario, a small, eutrophic annual drawdown reservoir, some individuals of the chironomid Procladius bellus survive the winter drawdown.
2. With refilling of the reservoir in spring, colonization by P. bellus is continuous and there were three generations a year.
3. Production estimated by the size-frequency method was 117.12 kg (175 mg m−2) in 1980 and 70.14 kg (105 mg m-2) in 1981. Annual P:B was about 13 in both years.
4. Substantial slation-to-station variations in production occurred and overall production was lower than in shallow habitats.  相似文献   
58.
59.
ABSTRACT. Our knowledge of the diversity of amoeboid protists is rapidly expanding as new and old habitats are more fully explored. In 2003, while investigating the cause of an amoeboid disease afflicting lobsters on the East Coast, samples were examined for the presence of amoebae from the carapace washings of the American lobster, Homarus americanus . During this survey a unique community of gymnamoebae was discovered. Among the new taxa discovered was a small Thecamoeba -like organism with a single posteriorly directed pseudopodium. Although resembling Parvamoeba rugata , this amoeba displayed distinctive morphology from that isolate or any other amoebozoan. Phylogenetic analysis shows this amoeba is distantly related to the Thecamoebidae. In this paper we describe the unique morphology of a second species of Parvamoeba and discuss its phylogenetic position with respect to the "Amoebozoa."  相似文献   
60.
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