Showing papers by "A. Townsend Peterson published in 1998"

Problems with areal definitions of endemism: the effects of spatial scaling

Abstract: Summary The concept of endemism is useful in quantifying the biological uniqueness of an area, and has been used by many authors as a meaningful alternative to simple species richness. The traditional definition of endemism includes those species with ranges restricted to a particular region, and therefore is useful only in reference to that region. To compare different regions, however, a standardized approach is required, so several authors began using area-based definitions. Accordingly, those species with ranges smaller than a particular area (e.g. 50,000 km 2) are deemed endemic. Nevertheless, several problems are associated with this approach: as the area threshold changes, scaling of endemism also changes, producing a different picture of endemism for each spatial scale. Moreover, the areal definition assumes equal levels of heterogeneity in different landscapes (clearly a simplification), which overemphasizes fine-grained regions. Herein, the importance of distinguishing the regional definition (endemism) from the areal definition (range restriction) is emphasized, and investigators are encouraged to consider multiple spatial scales and geographic dimensions in evaluations of biodiversity.

Genetic endangerment of wild Red Junglefowl Gallus gallus

Abstract: Domestic chickens were derived from the wild Red Junglefowl Gallus gallus. A survey of 745 museum specimens of Red Junglefowl suggests that most wild populations have been contaminated genetically by introgression of genes from domestic or feral chickens. A male eclipse plumage, which appears to be an indicator of pure wild genotypes, was found in populations in the western and central portions of the species's range, but not in the easternmost populations. Eclipse plumages probably disappeared from extreme south-eastern Asia and the Philippines prior to the advent of intensive scientific collecting (about 1860) and have not been observed in Malaysia and neighbouring countries since the 1920S. Populations exhibiting eclipse plumages were found in north-eastern India as late as the 1960s, but the dense human populations there make their continuing genetic integrity uncertain. These data suggest that surveys of wild and captive populations should be undertaken to assess the genetic integrity of this species. A re-evaluation of the conservation status of Red Junglefowl might then follow.

New Species and New Species Limits in Birds

Abstract: IN THIS ISSUE OF THE AUK, two papers provide a fascinating illustration of the state of studies of avian biodiversity. First, Whitney and Alvarez (1998) describe a new species of Herpsilochmus antwren from Peru and Ecuador. Second, Isler, Isler, and Whitney (1998) present an interesting application of vocal characters to delimiting species. This pair of papers provides material for reflection on the true dimensions of world avian diversity and its study. Slightly more than 50 years ago, Ernst Mayr (1946) stated "The total figure of 8,616 [bird] species [in the world] is ... probably within five per cent, and certainly within ten per cent, of the final figure . . . I doubt that in the entire world even as many as 100 new species remain to be discovered." A steady stream of descriptions of species new to science from diverse regions of the world nevertheless suggests that the supply is not yet exhausted. The Andes and adjacent regions of South America have proved to be a reliable source, as have Asia, southeastern South America, Africa, and even the Philippines and Mexico. The period 1941 to 1997 yielded at least 163 valid species descriptions, with no sign of exhausting the supply (Amadon and Short 1992). In fact, my estimates for a 1990s rate actually suggest an increase over rates from the 1970s and 1980s (Fig. 1), probably as a result of increased awareness of the importance of song characters in identifying new species (Parker 1991). Thus, Mayr's prophecy of

Distribution and conservation of birds of northern

Abstract: Patterns of distribution, diversity, and endemism in the birds of northern Central America were analyzed based on 541 avian species in 24 biotic regions. Many contrasts were apparent. For example, whereas species richness was concentrated in the Atlantic lowlands, with the Pacific lowlands, interior valleys, montane areas, and the Yucatan Peninsula less diverse; species endemic to the entire region were concentrated in the mountains and in the Yucatan Peninsula. Geographic patterns of endemism presented contrasts depending on the spatial scale of analysis. In contrast to overall patterns, species narrowly endemic to single geographic units were concentrated along the Pacific Coast of Chiapas and in southern Veracruz. Conservation implications of these results were explored using complementarity algorithms, producing ordered regional priority lists for the creation of optimal reserve systems. Finally, a plan of action for the study and conservation of avian diversity in northern Central America is outlined, including elements of basic inventory, systematics, and geographic analysis. Some of the earliest studies of New World