The North American Latitudinal Gradient in Species Richness and Geographical Range of Freshwater Crayfish and Amphipods

1992 ◽  
Vol 139 (2) ◽  
pp. 342-354 ◽  
Author(s):  
Robert France
Keyword(s):  
Species Richness ◽  
North American ◽  
Latitudinal Gradient ◽  
Geographical Range ◽  
Freshwater Crayfish ◽  
The North

scholarly journals Phylogenetic support for the Tropical Niche Conservatism Hypothesis despite the absence of a clear latitudinal species richness gradient in Yunnan's woody flora

2014 ◽  
Vol 11 (5) ◽  
pp. 7055-7077 ◽  
Author(s):  
G. Tang ◽  
M. G. Zhang ◽  
C. Liu ◽  
Z. Zhou ◽  
W. Chen ◽  
...  
Keyword(s):  
Species Richness ◽  
Phylogenetic Diversity ◽  
Latitudinal Gradient ◽  
Extreme Temperature ◽  
Woody Species ◽  
Niche Conservatism ◽  
The North ◽  
Related Plant ◽  
Species Richness Gradient ◽  
The Tropics

Abstract. The Tropical Niche Conservatism Hypothesis (TCH) tries to explain the generally observed latitudinal gradient of increasing species diversity towards the tropics. To date, few studies have used phylogenetic approaches to assess its validity, even though such methods are especially suited to detect changes in niche structure. We test the TCH using modeled distributions of 1898 woody species in Yunnan Province (southwest China) in combination with a family level phylogeny. Unlike predicted, species richness and phylogenetic diversity did not show a latitudinal gradient, but identified two high diversity zones, one in Northwest and one in South Yunnan. Despite this, the underlying residual phylogenetic diversity showed a clear decline away from the tropics, while the species composition became progressingly more phylogenetically clustered towards the North. These latitudinal changes were strongly associated with more extreme temperature variability and declining precipitation and soil water availability, especially during the dry season. Our results suggests that the climatically more extreme conditions outside the tropics require adaptations for successful colonization, most likely related to the plant hydraulic system, that have been acquired by only a limited number of phylogenetically closely related plant lineages. We emphasize the importance of phylogenetic approaches for testing the TCH.

Towards a Biogeography of North American Charophytes

1999 ◽  
Vol 47 (3) ◽  
pp. 445 ◽  
Author(s):  
Henry Mann ◽  
Vernon W. Proctor ◽  
Alberto S. Taylor
Keyword(s):  
Species Richness ◽  
North American ◽  
Ecological Niches ◽  
Physical Parameters ◽  
South American ◽  
Lake Titicaca ◽  
The Past ◽  
The North ◽  
The Stability

The great bulk of the world’s charophyte literature of the past 100 years or more suffers from several major limitations. Much is entirely descriptive with but few attempts to ascribe any functionality to the features under consideration, or how they adapt such species to their respective ecological niches. Charophyte distributions have been attributed almost entirely to physical parameters with virtually no consideration given to the role of aquatic herbivores or other biotic environmental factors. Furthermore, most workers have focused on relatively restricted areas with little or no reference to others either near or far removed. That there is much to be gained from a wider focus (both spatially and conceptually) that incorporates greater conjecture as well as enhanced collaboration is here suggested. How are the charophyte floras of one region similar to, or different from, those of another, and, of particular significance, ‘Why?’ The authors, being North American, focus on that continent but with the firm conviction that most generalities applicable there hold equally true for other landmasses, and have done so for the previous 10, if not 100, million years. This account focuses first, if somewhat superficially, on 14 widely distinct North American charophyte communities (plus South American Lake Titicaca) and then in greater detail on four of those. Among other issues considered are how species richness relates to latitude; why some geographical entities support more charophyte species than do others; the extent to which charophyte floras reflect the availability of different habitats; the contributions of herbivory to the preceding; the stability of the North American charophyte flora; the ecological considerations most often reflected by charophyte zonation and how–or to what extent–range extensions reflect niche preferences or requirements. While the authors well appreciate just how minimal their efforts may appear a century hence, at least they hope to have placed on the table some considerations with which colleagues from other landmasses may agree, disagree or suggest modifications.

scholarly journals Using a large-scale biodiversity monitoring dataset to test the effectiveness of protected areas at conserving North-American breeding birds

2018 ◽  
Author(s):  
Victor Cazalis ◽  
Soumaya Belghali ◽  
Ana S.L. Rodrigues
Keyword(s):  
Species Richness ◽  
Protected Areas ◽  
North American ◽  
Large Scale ◽  
Individual Species ◽  
Biodiversity Monitoring ◽  
Breeding Bird ◽  
The North ◽  
Forest Sites ◽  
Declining Species

AbstractProtected areas currently cover about 15% of the global land area, and constitute one of the main tools in biodiversity conservation. Quantifying their effectiveness at protecting species from local decline or extinction involves comparing protected with counterfactual unprotected sites representing “what would have happened to protected sites had they not been protected”. Most studies are based on pairwise comparisons, using neighbour sites to protected areas as counterfactuals, but this choice is often subjective and may be prone to biases. An alternative is to use large-scale biodiversity monitoring datasets, whereby the effect of protected areas is analysed statistically by controlling for landscape differences between protected and unprotected sites, allowing a more targeted and clearly defined measure of the protected areas effect. Here we use the North American Breeding Bird Survey dataset as a case study to investigate the effectiveness of protected areas at conserving bird assemblages. We analysed the effect of protected areas on species richness, on assemblage-level abundance, and on the abundance of individual species by modelling how these metrics relate to the proportion of each site that is protected, while controlling for local habitat, altitude, productivity and for spatial autocorrelation. At the assemblage level, we found almost no relationship between protection and species richness or overall abundance. At the species level, we found that forest species are present in significantly higher abundances within protected forest sites, compared with unprotected forests, with the opposite effect for species that favour open habitats. Hence, even though protected forest assemblages are not richer than those of unprotected forests, they are more typical of this habitat. We also found some evidence that species that avoid human activities tend to be favoured by protection, but found no such effect for regionally declining species. Our results highlight the complexity of assessing protected areas effectiveness, and the necessity of clearly defining the metrics of effectiveness and the controls used in such assessments.

Abundance, species richness and energy availability in the North American avifauna

2006 ◽  
Vol 15 (4) ◽  
pp. 372-385 ◽  
Author(s):  
Karl L. Evans ◽  
Neil A. James ◽  
Kevin J. Gaston
Keyword(s):  
Species Richness ◽  
North American ◽  
Energy Availability ◽  
The North

Acorn Size and Geographical Range in the North American Oaks (Quercus L.)

1990 ◽  
Vol 17 (3) ◽  
pp. 327 ◽  
Author(s):  
Marcelo A. Aizen ◽  
William A. Patterson
Keyword(s):  
North American ◽  
Geographical Range ◽  
The North ◽  
Acorn Size

1588: The Bicalutamide Early Prostate Cancer Program: Findings of the North American Trial at 7.7 Years' Median Follow-Up

2006 ◽  
Vol 175 (4S) ◽  
pp. 511-512
Author(s):  
David G. McLeod ◽  
Ira Klimberg ◽  
Donald Gleason ◽  
Gerald Chodak ◽  
Thomas Morris ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
North American ◽  
Early Prostate Cancer ◽  
The North ◽  
Cancer Program
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