Historical Rarity Research Articles

Analysis of the genetic variability in a sample of the remaining group of Spix's Macaw ( Cyanopsitta spixii, Psittaciformes: Aves) by DNA fingerprinting

The Spix's Macaw Cyanopsitta spixii is the world's most endangered parrot. There is only one male in the wild and 39 birds maintained in captivity. Among these, only nine were originally from the wild. The genetic variability of seven captive birds (six originally from the wild) was estimated using Jeffreys' human minisatellite probes 33.15 and 33.6. The similarity indexes obtained were close to those observed between fullsibs in other bird species. This result supports the evidence of its historical rarity in the wild and suggest that the birds studied belong to a small population. Thus, the technique applied here is an important tool for monitoring the remaining genetic variability of the Spix's Macaw.

USING LANDSCAPE HIERARCHIES TO GUIDE RESTORATION OF DISTURBED ECOSYSTEMS

Reestablishing native plant communities is an important focus of ecosystem restoration. In complex landscapes containing a diversity of ecosystem types, restoration requires a set of reference vegetation conditions for the ecosystems of concern, and a predictive model to relate plant community composition to physical variables. Restoration also requires an approach for prioritizing efforts, to facilitate allocation of limited institutional resources. Hierarchy theory provides a conceptual approach for predicting plant communities of disturbed ecosystems and, ultimately, for prioritizing restoration efforts. We demonstrate this approach using a landscape in southwestern Georgia, USA. Specifically, we used an existing hierarchical ecosystem classification, based on geomorphology, soil, and vegetation, to identify reference plant communities for each type of ecosystem in the landscape. We demonstrate that ecosystem identity is highly predictable using: only geomorphic and soil variables, because these upper hierarchical levels control the development of vegetation, a lower hierarchical level. We mapped the potential distribution of reference ecosystems in the landscape and used GIS (geographic information systems) to determine relative abundance of each ecosystem, as a measure of its historical rarity. We joined the reference ecosystem map with a current cover map to determine current abundance of each reference ecosystem, and percentage conversion to different disturbance classes. We show that over half of the landscape supports something other than reference plant communities, but degree of rarity varies widely among ecosystems. Finally, we present an index that integrates information on historical and current rarity of ecosystems, and disturbance levels of individual polygons, to prioritize restoration efforts. The premise of the index is that highest priority be given to restoring (1) currently rare ecosystems that were also historically rare and (2) the least disturbed examples of these ecosystems, as these will require the least effort to restore. We found that 80% of high-priority sites occur within just three (of 21) ecosystems. Moreover, the high-priority ecosystems all occur within stream valleys. Our approach provides managers with a straightforward methodology for determining potential distribution of reference ecosystems and for allocating efforts and resources for restoration in complex landscapes. Development of a priority index for a specific landscape requires an understanding of the hierarchical relationships among geomorphology, soil characteristics, and plant communities, in addition to well-defined restoration objectives.

Synovial sarcoma metastatic to the mandible: Report of two cases

While tumor metastasis to the mandible is considered rare, its true incidence probably is underreported for several reasons. First, the historical rarity of this manifestation of malignancy may result in a lowered index of suspicion on the part of clinicians; radiographic and radionuclide bone surveys done during metastatic workups seldom include separate views of the jaws. Second, asymptomatic or mildly symptomatic lesions may be overlooked in cancer patients, or may be thought to be odontogenic or benign in nature. Finally, patients may die before jaw metastases become apparent, and postmortem examinations rarely include the mandible. The discovery of metastasis may signal a change in prognosis that can affect both oncologic treatment planning and patient management. A mandibular lesion may provide the first indication that a known primary cancer has spread or that generalized metastatic disease is progressing. It can indeed be the very first sign of an occult malignancy. Metastasis is one of the major causes of treatment failure in clinical oncology. 1 For these reasons, the importance of careful clinical and radiographic investigation of apparent dental aberrations in cancer patients cannot be overstated. The following report describes, in two patients, the metastasis of a very rare soft-tissue sarcoma to the mandible, and its presentation, diagnosis, clinical course, and outcome.

Misapplications Reviews: The Capital Punishment Controversy: Part II

In the first installment of this two-part series, I discussed some studies on the deterrent effect of the death penalty that I view as clearly unreliable. Here I will consider some other analyses that seem worthy of greater attention. That done, I'll move on to some general musings (broodings?) on what the capital punishment controversy tells us about the conduct of social science research. A whole host of social, demographic, and economic factors can cause homicide rates to differ over time and across regions. And given the historical rarity of executions, variations in their use would at most seem among the lesser causes of any differences observed. Thus, careful researchers on capital punishment have recognized that, unless the major influences on murder levels have been accurately identified and measured, there is little hope for any trustworthy answer to a question about deterrence.