共查询到20条相似文献,搜索用时 7 毫秒
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B. Blumenberg 《Genetica》1986,68(2):81-86
The genetic profile of theFelis catus population of Humboldt County, California, has been determined. Genetic distance analysis reveals closest affinities with
east coastFelis and a statistically identical relationship with northern New Spain populations. Evidence of allele input from early 19th
century Russia is discernible but weak. Denver, Colorado and Reno, Nevada, retain evidence of allele input from New Spain
populations. Of the Northwest coast populations studied, Vancouver, British Columbia, alone does not retain evidence of the
postulated allele input from late 18th century and early 19th century European sources. 相似文献
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Ann E. Gray Timothy J. Mulligan Robert W. Hannah 《Environmental Biology of Fishes》1997,49(2):227-238
The bat ray, Myliobatis californica, is the most common, large predatory fish in Humboldt Bay, California. To prevent bat ray predation on cultured oyster beds, much effort has focused on reducing their population. A 13 month study was conducted in Humboldt Bay to examine the rays' use of the bay, population structure, and feeding ecology. Bat rays are seasonally found in Humboldt Bay during the spring, summer, and early fall months. Adult rays were most abundant during the summer months, while numbers of juveniles increased through the summer and early fall, indicating that Humboldt Bay is an important pupping and nursery ground. Very few rays were found in the bay during the colder months of the year. This decline in abundance is attributed to cooler water temperatures (< 10° C). The stomach contents from 503 bat rays were examined. Overall, clams were the predominant prey item. The index of importance and Shannon-Weiner diversity index indicated that food habits of bat rays change with increasing size. Larger prey items and a wider variety of prey items were consumed as rays increased in size. Dietary importance of small clams and Crangon shrimp decreased with increasing ray size, while the importance of larger prey items (e.g. large clams, Cancer crabs, blue mud shrimp, echiuran worms) increased. Predation on oysters was rare. Differences between the diets of male and female rays of similar sizes were also observed. 相似文献
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Rose S 《Biologist (London, England)》2001,48(2):100
No, not a reflection on the environmental threat to the Galapagos. Rather, it is a reference to Darwin's own complaint, towards the end of his life, concerning those who misunderstood and misrepresented his theories. 相似文献
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Lewis HS 《Current anthropology》2001,42(3):381-406
This paper presents a new reading of Franz Boas's philosophy of science and his approach to the understanding of culture and behavior. It points out that his approach had important parallels with the worldview of the major figures associated with pragmatism and suggests that a similar perspective can be useful today. 相似文献
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B. K. Hall 《Zeitschrift fur angewandte Ichthyologie》2010,26(2):148-151
Darwin provided us with the theory of evolutionary change through natural selection. Just as important to the science of biology was Darwin’s recognition that all organisms could be classified and were related to one another because they arose from a single common universal ancestor – what we know as the universal tree of life (UtoL). All the features of the skeletal biology of fish therefore can be explained, both in an evolutionary framework (ultimate causation) and in the framework of development, growth and physiology (proximate causation). Neither approach is complete without the other. I will outline the elements of Darwin’s theories on evolution and classification and, as importantly, discuss what was missing from Darwin’s theories. An important class of evidence for evolution used by Darwin came from embryology, both comparative embryology and the existence of vestiges and atavisms. After discussing this evidence I examine some fundamental features of skeletal development and evolution These include: the presence of four skeletal systems in all vertebrates; the existence of two skeletons, one based on cartilage, the other on bone and dentine; the modular nature of skeletal development and evolution; and the plasticity of the skeleton in response to either genetic or environmental changes. 相似文献
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The spatial distribution of an intertidal population of the barnacleBalanus amphitrite was studied close to a sewage outfall nearQuequén, Argentina (38° 34S,58° 38 30 W). All individuals within an areaof 0.8 m2 were mapped during 12 censuses, from September 1990to May 1993. Population density within the study area varied between 401 and99 ind m-2. Spatial pattern was analysed using mean distancesto the nearest neighbour (NND), goodness of fit tests between observed andexpected frequency distributions of NND, and analysis of crowding. Thespatial pattern of the population was clumped during most of the studyperiod. This trend persisted, although not reaching statisticalsignificance, when the population density decreased as a consequence ofmortality and failure of successive annual recruitments. The cohortrecruited in summer 1992 (49 individuals) was randomly distributed relativeto adult barnacles already present within the study area. No consistentrelationship was observed between mortality and NND. 相似文献
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J. Sébastien Steyer 《Comptes Rendus Palevol》2009,8(2-3):233-241
A critical review of Darwin's publications shows that he did not dissert much about amphibians, in comparison with the other tetrapods. However, in “A Naturalist's Voyage round the World”, Darwin described for the first time several amphibian species and was surprised by their peculiar way of life, terrestrial or euryhaline. These amphibian observations around the world led Darwin to discuss evolutionnary notions, like developmental heterochronies or evolving convergences, and later to illustrate his famous natural selection theory. This is confirmed, for example, by the publication of “On the Origin of Species” where Darwin ironically questioned creation theory, trying to explain the absence of amphibians on oceanic islands. Lamarck also considered amphibians as relevant material to illustrate his theory of acquired character heredity. These historical uses of lissamphibians as evolutionary models have been mostly realized before any amphibian fossil discovery, i.e. out of a palaeontological context. 相似文献
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E. I. Kolchinsky 《Paleontological Journal》2010,44(12):1467-1470