2 resultados para division of responsibilities

em DigitalCommons@University of Nebraska - Lincoln


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Prior studies of phylogenetic relationships among phocoenids based on morphology and molecular sequence data conflict and yield unresolved relationships among species. This study evaluates a comprehensive set of cranial, postcranial, and soft anatomical characters to infer interrelationships among extant species and several well-known fossil phocoenids, using two different methods to analyze polymorphic data: polymorphic coding and frequency step matrix. Our phylogenetic results confirmed phocoenid monophyly. The division of Phocoenidae into two subfamilies previously proposed was rejected, as well as the alliance of the two extinct genera Salumiphocaena and Piscolithax with Phocoena dioptrica and Phocoenoides dalli. Extinct phocoenids are basal to all extant species. We also examined the origin and distribution of porpoises within the context of this phylogenetic framework. Phocoenid phylogeny together with available geologic evidence suggests that the early history of phocoenids was centered in the North Pacific during the middle Miocene, with subsequent dispersal into the southern hemisphere in the middle Pliocene. A cooling period in the Pleistocene allowed dispersal of the southern ancestor of Phocoena sinusinto the North Pacific (Gulf of California).

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At the first Vertebrate Pest Control Conference in 1964, I traced the history of plague control in California and outlined a revised approach, based on newer concepts of plague ecology. In our state of relative ignorance, this required a number of unproved assumptions about plague occurrence in California that verged on crystal ball gazing. These were principally that (1) plague persists in relatively resistant rodent species in certain favorable locations, (2) ground squirrels and chipmunks experience periodic epizootics, but are not permanent reservoirs, (3) plague "foci" of the past were merely sites of conspicuous epizootics, they did not necessarily correspond to permanent foci, and could result from epizootic migrations over considerable distances, and (4) a number of assumptions about areas of greatest epizootic potential can be made by analyzing the pattern of recurrent plague outbreaks in the past. Since then the validity of these assumptions has been tested by the largest outbreak of plague since the early 1940's. We believe that the results have proved the crystal ball largely correct, resulting in much more precise and efficient epizootic surveillance and deployment of control measures than in the past. The outbreak was for us an administrative emergency that exceeded the capacities of the State Health Department. We greatly appreciated the vital help and cooperation of other agencies and individuals. The U.S, Public Health Service accepted a heavy burden of laboratory testing through its San Francisco Field Station, and provided emergency field personnel. The contributions of State Department of Agriculture, Bureau of Weed and Vertebrate Pest Control; U.S. Parks, Forest Service and Bureau of Land Management; local health and agriculture department; and State Division of Parks personnel were essential in accomplishing control work, as well as epizootic surveillance.