A reduction in forest area should result in a reduction of its number of species and, moreover, do so in a characteristic way according to the familiar species-area relationship. Brooks, Pimm & Collar (1997) applied this formula to the losses in forest area in the Philippines and Indonesia. Independently derived totals of the number of endemic bird species that are threatened with extinction broadly agree with these predicted losses. In some cases, however, predicted losses overestimate or underestimate the actual numbers of threatened species.Resource Type: Journal Papers
Small local hunting communities in Siberia are very distant from any governmental control. Hunted waterbird species, including globally and regionally threatened species, rely for their well-being on the self regulation of remote hunting communities. Interviewed hunters showed a profound knowledge of Baikal Teal, its population status, and the causes of their past decline. Whether the knowledge is shared by other communities in the region and beyond in Northern Siberia needs verification.
This study demonstrates the utility of carbon isotope discrimination in describing genetic adaptation to arid environments, although it is probably most useful in detecting differentiation when the strategy of the species under investigation is to increase water use efficiency, rather than drought-avoidance. The results suggest that populations on the eastern and western sides of the Andes should be treated as separate management units for the purposes of conserving the genetic resource of this species.Resource Type: Journal Papers
Since about 1600, 486 animal species have been recorded extinct. This represents about 0.04 of all animal species so far described. In the same period, 600 plant species are known to have disappeared, about 0.25 of the total. These figures are much smaller than those of the Permian/Triassic and Cretaceous/Tertiary mass extinctions. One might therefore conclude that at present life on earth is at comparatively little risk of extinction. However, there is a growing body of data to show that the converse is true.Resource Type: Journal Papers
The effects of Pleistocene glaciations on the genetic characteristics of the most austral conifer in the world, Pilgerodendron uviferum, were analysed with specific reference to the hypothesis that the species persisted locally in ice-free areas in temperate South America.
Results indicated that Pilgerodendron populations are highly monomorphic, probably reflecting past population bottlenecks and reduced gene flow. Southernmost populations tend to be the least genetically variable and were therefore probably more affected by glacial activity than northern ones. Populations located outside ice limits seem to have been isolated during the glacial period. The presence of centres of genetic diversity, together with the lack of a significant correlation between genetic and geographical distances and the absence of geographical patterns of allelic frequencies at most analysed alleles, may indicate that Pilgerodendron did not advance southward after the last glaciation from a unique northern refugium, but spread from several surviving populations in ice-free areas in Patagonia instead.Resource Type: Journal Papers
©2013 UNEP All rights reserved