Species Richness, Environmental Correlates, and Spatial Scale: A Test Using South African Birds

Rensburg, Van; Chown,; Gaston,

doi:10.2307/3078914

Cited by 48 publications

(82 citation statements)

References 19 publications

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“…This is in accord with the findings of Van Rensburg et al (2002), and those of similar studies of several other assemblages (Waide et al 1999;Mittelbach et al 2001). Within South Africa, the monotonic increase of avian species richness with energy at a quarter-degree resolution is not a by-product of more productive areas having a greater geographical extent (cf.…”

Section: Discussionsupporting

confidence: 81%

“…Measures of NDVI were used as measures of energy because they were available at a finer resolution than the half-degree NDVI 0 0.62 measures of net primary productivity (NPP) (Woodward et al 2001) that have previously been employed in documenting a species-energy relationship for the South African avifauna (Van Rensburg et al 2002). However, at a half-degree resolution the two are closely correlated (r 2 = 0.81, p Ͻ 0.001).…”

Section: (A) Datamentioning

confidence: 99%

“…These have variously been found to be positive, negative and hump-shaped. Some examples of the first two comprise the extremes of the third, but others apparently do not, and there is growing evidence for dependence of the form of observed patterns on spatial scale (Waide et al 1999;Mittelbach et al 2001;Whittaker et al 2001;Chase & Leibold 2002;Van Rensburg et al 2002). Such complexity has, perhaps inevitably, led to a multitude of explanations for species-energy relationships, rooted in a variety of evolutionary and ecological processes (Kerr & Packer 1997;Rohde 1997;Rosenzweig & Sandlin 1997;Srivastava & Lawton 1998;Allen et al 2002;Storch 2003).…”

Section: Introductionmentioning

confidence: 99%

“…We use as a case study the avian species assemblage of South Africa and Lesotho, for which the existence of such a relationship is already well established (Van Rensburg et al 2002). First, we describe (i) the observed pattern and test whether the observed species-energy relationship is attributable to (ii) the species-area relationship, as the existence of such an effect could influence subsequent considerations (Rosenzweig 1995 and geographical ranges.…”

Section: Introductionmentioning

confidence: 99%

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Structure of the species–energy relationship

Bonn

Storch

Gaston

2004

Proc. R. Soc. Lond. B

109

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The relationship between energy availability and species richness (the species-energy relationship) is one of the best documented macroecological phenomena. However, the structure of species distribution along the gradient, the proximate driver of the relationship, is poorly known. Here, using data on the distribution of birds in southern Africa, for which species richness increases linearly with energy availability, we provide an explicit determination of this structure. We show that most species exhibit increasing occupancy towards more productive regions (occurring in more grid cells within a productivity class). However, average reporting rates per species within occupied grid cells, a correlate of local density, do not show a similar increase. The mean range of used energy levels and the mean geographical range size of species in southern Africa decreases along the energy gradient, as most species are present at high productivity levels but only some can extend their ranges towards lower levels. Species turnover among grid cells consequently decreases towards high energy levels. In summary, these patterns support the hypothesis that higher productivity leads to more species by increasing the probability of occurrence of resources that enable the persistence of viable populations, without necessarily affecting local population densities.

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Section: Discussionsupporting

confidence: 81%

Section: (A) Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure of the species–energy relationship

Bonn

Storch

Gaston

2004

Proc. R. Soc. Lond. B

109

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“…The few studies that have looked into this issue report that when correlations are found these are usually weak and vary in strength with the scale of analysis (Gaston 1996, Bokma et al 2001, Jetz & Rahbek 2001, van Rensburg et al 2002. Covariation has been explained by a shared latitudinal effect (Pearson & Cassola 1992, Flather et al 1997, however, since latitude per se does not affect species richness, the pattern remains largely unexplained.…”

Section: Introductionmentioning

confidence: 99%

Mammal and butterfly species richness in Chile: taxonomic covariation and history

Samaniego

Marquet

2009

Rev. chil. hist. nat.

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Understanding species richness spatial distribution is of fundamental importance to face the current biodiversity crisis that affects biotas around the world. Taxonomical covariation in species occurrence may offer the possibility to identify common factors that restrict species richness, as well as some guidelines to the identification of key areas for conservation purposes. To this aim, we analyze the geographic distribution of mammals and butterflies in Chile using 0.5° latitude and longitude quadrats. We found that, for both taxa, there is a strong bell-shaped latitudinal gradient in species richness with a peak at mid-latitudes (33-43° S). The results from multiple stepwise regression analysis shows that for both taxa productivity measured using the Normalized Difference Vegetation Index (NDVI) is the most important variable driving changes in species richness followed by glaciation and elevation depending on the taxa. Mid-domain effects were either weak or unimportant in affecting the richness pattern. Variance partitioning analysis shows that the spatial components alone are irrelevant to the richness pattern. We show that spatial covariation in richness of butterflies and mammals, is strongly influenced by spatial scale, possibly as the result of a scale-dependent effects on individual species ranges, whereas factors related to specific ecological characteristics, are more important at smaller scales. Because richness gradients are ultimately the product of speciation and colonization processes on longer time scales, we propose that species richness gradients in Chile may be explained by the interaction between historical processes associated to desertification and glaciation together with productivity. The former sets the domain within which productivity produces a similar richness pattern for both taxa despite their different phylogenetic histories and physiological requirements.Key words: lepidoptera, mammalia, Chile, latitudinal gradient, species richness. RESUMENComprender la distribución espacial de la riqueza de especies es un aspecto de fundamental importancia para enfrentar la actual crisis que afecta a las biotas del mundo. En este sentido, el estudio de la covariación taxonómica en el espacio nos da la posibilidad de identificar factores comunes que restringen la riqueza, además de ofrecer una oportunidad para identificar áreas claves para la conservación. Con este propósito, analizamos la distribución geográfica de mamíferos y mariposas en Chile usando cuadrículas de 0,5° de latitud y longitud. Para ambos taxa, existe una distribución latitudinal unimodal con un máximo de riqueza a latitudes intermedias (33-43° S). Usando una regresión múltiple paso a paso mostramos que la productividad es el factor gravitante para explicar la riqueza de ambos taxones seguido por efectos asociados a glaciaciones y elevación según sea el taxa. Efectos asociados al dominio medio muestran ser débiles o no significantes para determinar la distribución latitudinal de la riqueza en Chile. Un ánalisis de par...

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Relative influence of habitat heterogeneity, climate, human disturbance, and spatial structure on vertebrate species richness in Spain

Moreno‐Rueda

Pizarro

2008

Ecological Research

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Many factors affect the distribution of species richness. This study examines the relative influence of habitat heterogeneity, climate, human disturbance, and spatial structure on the species-richness distribution of terrestrial vertebrates (amphibians, reptiles, birds and mammals) in mainland Spain. The results indicate that spatial structure and environment exert similar influences on species richness. For all four taxa, species richness increases southward and northward, being lower in the center of the country, when controlled for other variables. This may be the result of a peninsular effect, as found in other studies, and reflect the importance of historical events on species richness in the Iberian Peninsula. Climate is more important than habitat heterogeneity in determining species richness. Temperature is positively correlated with amphibian, reptile, and bird species richness, while mammalian species richness is highest at intermediate temperatures. This effect is stronger in ectotherms than among endotherms, perhaps reflecting physiological differences. Precipitation positively correlates with bird and mammalian species richness, but has no effect on ectotherm species richness. Amphibian species richness increases with altitudinal range, and bird species richness with habitat diversity. Human population density is positively correlated with bird and mammalian species richness, but does not affect ectotherm species richness, while amphibian and bird species richness is highest at moderate levels of human land alteration (farmland). However, unexplained variance remains, and we discuss that the effects of environmental variables on species richness may vary geographically, causing different effects to be obscured on a national scale, diminishing the explanatory power of environmental variables.

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Species Richness, Environmental Correlates, and Spatial Scale: A Test Using South African Birds

Cited by 48 publications

References 19 publications

Structure of the species–energy relationship

Structure of the species–energy relationship

Mammal and butterfly species richness in Chile: taxonomic covariation and history

Relative influence of habitat heterogeneity, climate, human disturbance, and spatial structure on vertebrate species richness in Spain

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