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From observations of the spatial distribution of humpback whales in the Mexican Pacific between 1981 and 1986, it is possible to recognize four subregions: 1) the southern coast of Baja California; 2) the northern Gulf of California, including the Midriff Islands; 3) the mainland coast of Mexico, including the Isla Isabel and Islas Tres Marias and 4) the Revillagigedo Archipelago. The seasonal distribution of whales near the Mexican mainland and the Revillagigedo Archipelago extends from November to May and is similar to that of other winter breeding grounds, including the Hawaiian Islands. Along the southern coast of Baja California, whales have been observed from September to April, possibly indicating a shorter migratory route. In the northern Gulf of California, however, humpback whales have been reported throughout the year and are occasionally observed feeding during both summer and winter months. The degree of individual movement between the four subregions is still unknown. The number of individual humpback whales identified photographically in recent years suggests that there ate more whales in the Mexican Pacific than previously reported. 相似文献
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Sargassum is one of the most species‐rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific‐Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL‐IGS‐rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL‐IGS‐rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well‐resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events. 相似文献
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Zertuche-Gonzalez J. A. Pacheco-Ruiz I. Cabello-Pasini A. Chee-Barragan A. Guzman J.M. Galvez A. & Arroyo E. Yarish C. 《Journal of phycology》2000,36(S3):72-72
The marine flora of Panama remains poorly described to date, having been described from a few sporadic and species poor (<50 species) collections in the early half of the century and a couple of dedicated surveys in the latter half. With the exception of a few studies that have focused on particular genera or species, only a single marine floral survey has been published in the past three decades. In 1999 we collected marine algae from nearly 100 different collection sites along both coasts of Panama over a 10 month period of time. Over 1500 specimens have been curated, representing 250 Caribbean species and 117 Pacific species. This is an increase in algal diversity of approximately 100 and 50% for the Caribbean and Pacific flora, respectively, relative to Earle's compilation of 1972. We estimate that algal diversity in Panama may approach 450 species as the remaining 30% of the collection is identified and previous records are incorporated. Aspects of biogeography will be discussed in light of such extraordinary diversity over a relatively confined region. 相似文献
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The relative abundance of the most common cetacean schools in the eastern tropical Pacific Ocean for 1977–1980 are estimated based on encounter rates with tuna purse-seiners. No temporal trends were apparent in the relative abundance estimates. The geographic distributions for eight different school types are described. Multivariate statistical techniques are used to investigate interrelations between species and relationships to parameters of the physical environment. The results suggest three major species groupings: (1) an inshore grouping of bottlenose dolphins ( Tursiops truncates ), Risso's dolphin ( Grampus griseus ), pilot whales ( Globicephala macrorhynchus ) and, to a lesser extent, common dolphins ( Delphinus delphis ); (2) an offshore pelagic grouping of spotted and spinner dolphins ( Stenella attenuate and S. longirostris ); and (3) an association between pilot whales and common dolphins that overlaps the first grouping in inshore areas and also tends to be segregated from the second grouping. The results also suggest that relative densities of different school types are strongly related to physical environmental parameters, the most important being sea surface temperature, depth of the thermocline and thickness of the oxygen minimum layer. 相似文献
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Anthropologists have long been inclined to view China from the perspective of a state-society dichotomy. In this model, the inevitable consequence of economic reform is that – especially at the local level – the state must yield more and more of its power to entrepreneurs, foreign investors, non-state organizations, and local communities. Not only does this approach distort the role of the state in society, but by placing the state above and outside society it also excludes it from the anthropological gaze. This article proposes an anthropology of the Chinese state which does not merely view the state in society, but also investigates the state itself as society. Drawing on fieldwork in northeastern Yunnan province, I illustrate this general point by investigating the changing role of the local state in economic development. This agenda for an anthropology of the Chinese state resonates both with the recent 'reinvention' of the subfield of political anthropology with its focus on governmentality, policy, and rights, and with recent calls by political scientists for the development of an interdisciplinary anthropology of the developmental state. 相似文献
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AERIAL CENSUS OF PACIFIC WALRUSES IN THE CHUKCHI SEA, 1985 总被引:4,自引:0,他引:4
James R Gilbert 《Marine Mammal Science》1989,5(1):17-28
The U.S. Fish and Wildlife Service conducted a survey of the walruses in the pack ice of the Chukchi Sea between 16 September and 2 October 1985, as part of a joint effort with the Soviet Union to estimate the size of the Pacific walrus population. American observers conducted censuses from two aircraft along randomly selected north–south lines over the pack ice. The observers counted walruses within a constant viewing angle that corresponded to a total strip width of 1.38 km at an altitude of 152 m.
In nine days of flying, 15,312 walruses were observed, of which 10,140 were on 5,764 km2 of census strips. Few walruses were observed east of 161°W longitude or west of 170°W longitude, hence the census effort was stratified. Walrus concentrations between 161° and 170° shifted slightly westward during the 2-wk duration of the censuses. The differences among days in observed walrus density were due to changes in the numbers of walruses on the ice within 37 km of the ice edge. The number of observable walruses in pack ice of the eastern Chukchi Sea was estimated to be 62,177 (SD = 19,480), based on censuses conducted on 29 and 30 September and 1 October. At that time there were also at least 15,238 in Bristol Bay, Bering Sea. The Soviets counted 39,572 on the shores of the western Chukchi and Bering seas and estimated 115,531 in pack ice of the western Chukchi Sea. Summing U.S. and Soviet estimates, the total population of Pacific walruses in 1985 was 232,518. This number was comparable with earlier estimates from censuses conducted jointly by the U.S. and the Soviets. However, information on fraction hauled out, segregation, and movements is needed for more precise estimates. 相似文献
In nine days of flying, 15,312 walruses were observed, of which 10,140 were on 5,764 km
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We estimated age at attainment of sexual maturity and examined reproductive seasonality for male spotted dolphins, Stenella attenuata , from the eastern tropical Pacific Ocean. Maturity was determined by histological examination of testes. Average age at sexual maturation was 14.7 yr (the mean of two readers' age estimates). Testis and epididymis weight and seminiferous tubule diameters were reliable indicators of maturity, whereas age, length and color phase were less reliable. Seasonality was determined by changes in testis and epididymis weight, relative quantity of spermatids and spermatozoa, and lumen diameter, as well as an index of testis development (weight of the right testis and epididymis divided by length of the right testis). Testis and epididymis weights and index values peaked in July and August, midway between two predicted mating seasons for the northern offshore stock, but spermatozoa levels were elevated during the predicted breeding seasons. 相似文献
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W. Stewart Grant Gunnar Sthl 《Evolution; international journal of organic evolution》1988,42(1):138-146
An allozyme investigation of 41 protein-coding loci in two morphologically similar fishes, Atlantic and Pacific cod, indicates that Pacific cod experienced a severe population bottleneck that led to the loss of gene diversity and gene expression. Pacific cod possesses a significantly lesser amount of gene diversity (H = 0.032) than Atlantic cod (H = 0.125) and lacks gene expression for Me-3. Allele-frequency distributions differ between species as predicted by neutral theory: Atlantic cod has a U-shaped distribution, which is expected for populations in drift-mutation equilibrium, whereas Pacific cod has a J-shaped distribution with an excess of low-frequency alleles. This excess may be explained by the appearance of new alleles through mutation which have not yet reached intermediate frequencies through drift. The population bottleneck in Pacific cod was most likely associated with founder populations that dispersed into the Pacific Ocean after the Bering Strait opened. Under the molecular-clock hypothesis a Nei genetic distance of 0.415 (based on 41 loci) suggests that Pacific cod dispersed into the Pacific Ocean soon after the Bering Strait opened in the mid-Pliocene, 3.0 to 3.5 million years ago. 相似文献
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Anthropological studies generally interpret discourses about witches and zombies in sub-Saharan Africa as critical commentary on the emergence of new forms of wealth, the commodification of labour, and the crisis of reproduction. Drawing on data collected in the Bushbuckridge area of the South African lowveld, I point to the limitations of these arguments and suggest that we can more fully capture the diverse and contradictory meanings of witches and zombies by separating discourses from actual accusations and from subjective realities. Whilst generic discourses highlight the use of zombies as a means of accumulating wealth, those accused of witchcraft are nearly always subordinate and impoverished persons who allegedly keep zombies as a means of survival. At the same time, these beliefs are connected to powerful psychological motivations, such as emotionally overwhelming experiences of bereavement, loss, and mourning. I suggest that witches and zombies derive their broad appeal from indeterminacy that defies interpretive control and constantly allows for alternative interpretations. 相似文献
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We have cultured green fluorescing heterotrophic dinoflagellates whose continuous green fluorescence is due to an unidentified compound, probably a flavin, that excites with blue (~460 nm) light and emits green (~535 nm) light. No evidence of bioluminescence was found, but we note that compounds with similar fluorescence characteristics have been associated with bioluminescence in other taxa. These cells, all naked gymnodinoids, are widespread and abundant in the Northwest Atlantic and Northeast Pacific Oceans (103–105 L?1). They comprise 4–100% of the total heterotrophic dinoflagellate component which, in turn, is usually equivalent magnitude to the phototrophic naked dinoflagellate component of the phytoplankton community. 相似文献
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Albert C. Smith 《American journal of botany》1973,60(5):479-490
The genus Metrosideros (Myrtaceae) is an abundant and taxonomically confusing component of the vegetation throughout much of its range. In the southern Pacific, from the New Hebrides eastward to the Society and Tuamotu Islands, the genus is represented by one variable species, M. collina (J. R. & G. Forst.) A. Gray, in which three widespread varieties seem to merit recognition. An attempt is here made to clarify the nomenclature and inter-relationships of these varieties. Additionally, two local endemics are related to the M. collina group—M. gregoryi Christophersen in Samoa and M. ochrantha A. C. Sm. (sp. nov.) in Fiji. 相似文献
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