On Latitudinal Gradients in Avian Diversity

Abstract

Species diversity patterns exist on at least three geographical scales: (1) the diversity in a sample drawn from a single community, often called within-habitat diversity; (2) the diversity occurring in a collection of similar habitats within a given region, here referred to as between-habitat diversity; and (3) the total diversity to be found in all the available habitats in a fairly large geographical area. Whittaker (1960) has termed these categories alpha, beta, and gamma diversity, respectively. the problem of latitudinal gradients by considering gamma-diversity patterns. Such approaches have usually resulted in hypotheses of an historical nature, stressing more rapid evolution in the tropics, less frequent and/or less rigorous climatic disturbances there, etc. (Dobzhansky 1950; Fischer 1961; Haffer 1969; Cook 1969). MacArthur (1965) has also made the distinction between theories relating to alpha-and gamma-diversity gradients.

Latitudinal Gradients of Biodiversity: Pattern, Process, Scale, and Synthesis

“…In general, species richness increased toward the equator (Anderson 1984; Blackburn & Gaston 1996a, 1997Buckton & Ormerod 2002;Cardillo 2002;Cook 1969;Currie 1991;Diniz-Filho et al 2002b;Gaston 2000;Rabinovich & Rapoport 1975;Rahbek & Graves 2001;Schall & Pianka 1978;Tramer 1974). Although methodological differences existed among studies, especially regarding the inclusion or exclusion of wintering ranges in the determination of species richness, results were correlated (Blackburn & Gaston 1996a, 1996b, 1997 or similar (Tramer 1974).…”

The Distribution of Bird Species in the New World: Patterns in Species Turnover

“…Bird species richness in the New World conforms to this general pattern. When this region is divided into quadrats (grid squares) of approximately equal area, those nearer to the equator incorporate the geographic ranges of a greater number of species than do those nearer the Poles (Dobzhansky 1950, MacArthur and Wilson 1967, Cook 1969, MacArthur 1969, Tramer 1974.…”

Biodiversity -the road to an atlas

“…These include maps for trees (Currie and Paquin, 1987;Currie, 1991;Schueler and McAllister, 1991), butterflies (Pearson and Cassola, 1992;Opler 1995), various groups of beetles (Erwin, 1970;Whitehead, 1972;Willis, 1972;Noonan, 1990;Pearson and Cassola, 1992), freshwater fish (McAllister et al, 1986), amphibians (Kiester, 1971;Currie, 1991), reptiles (Kiester, 1971;Schall and Pianka, 1978;Currie, 1991;Iverson, 1992), birds (Cook, 1969;MacArthur, 1969;Tramer, 1974;Pianka, 1978, Root, 1988;Currie, 1991;Pearson and Cassola, 1992;Price et al, 1995;O'Connor et al, 1996), mammals (Wilson, 1974;Glazier, 1980;Currie, 1991), and endangered plants, molluscs, fish and birds (Dobson et al, 1997). These maps have served to highlight the often wide variation in the spatial patterns of richness of different major groups of organisms, that is, the general lack of strong congruence in patterns of diversity (Schall and Pianka, 1978;Gaston, 1996b;1996c;Kerr, 1997).…”