Spatial Grain and the Causes of Regional Diversity Gradients in Ants

2003 ◽  
Vol 161 (3) ◽  
pp. 459-477 ◽  
Author(s):  
Michael Kaspari ◽  
May Yuan ◽  
Leeanne Alonso
Keyword(s):  
Regional Diversity ◽  
Diversity Gradients ◽  
Spatial Grain

Drivers of diversity gradients of a highly mobile marine assemblage in a mesoscale seascape

2020 ◽  
Vol 638 ◽  
pp. 149-164
Author(s):  
GM Svendsen ◽  
M Ocampo Reinaldo ◽  
MA Romero ◽  
G Williams ◽  
A Magurran ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Regression Tree ◽  
Demersal Fish ◽  
Open Ocean ◽  
Shared Resources ◽  
Thermal Front ◽  
Boosted Regression Tree ◽  
Diversity Gradients ◽  
Α Diversity ◽  
Bottom Depth

With the unprecedented rate of biodiversity change in the world today, understanding how diversity gradients are maintained at mesoscales is a key challenge. Drawing on information provided by 3 comprehensive fishery surveys (conducted in different years but in the same season and with the same sampling design), we used boosted regression tree (BRT) models in order to relate spatial patterns of α-diversity in a demersal fish assemblage to environmental variables in the San Matias Gulf (Patagonia, Argentina). We found that, over a 4 yr period, persistent diversity gradients of species richness and probability of an interspecific encounter (PIE) were shaped by 3 main environmental gradients: bottom depth, connectivity with the open ocean, and proximity to a thermal front. The 2 main patterns we observed were: a monotonic increase in PIE with proximity to fronts, which had a stronger effect at greater depths; and an increase in PIE when closer to the open ocean (a ‘bay effect’ pattern). The originality of this work resides on the identification of high-resolution gradients in local, demersal assemblages driven by static and dynamic environmental gradients in a mesoscale seascape. The maintenance of environmental gradients, specifically those associated with shared resources and connectivity with an open system, may be key to understanding community stability.

DIFFERENCES IN EXTINCTION RATES EXPLAIN CONTRASTING REGIONAL DIVERSITY PATTERNS IN MODERN TROPICAL BRYOZOANS

2017 ◽  
Author(s):  
Jeremy B.C. Jackson ◽  
◽  
Emanuela Di Martino ◽  
Paul D. Taylor ◽  
Kenneth G. Johnson
Keyword(s):  
Diversity Patterns ◽  
Regional Diversity ◽  
Extinction Rates

Nexus of self-organization: the expansion of collective responsibility networks among boatmen in nineteenth-century Chongqing

2021 ◽  
pp. 1-22
Author(s):  
Yiying Pan
Keyword(s):  
Nineteenth Century ◽  
Early Modern ◽  
Turning Points ◽  
Collective Responsibility ◽  
Local State ◽  
Self Organization ◽  
Modern China ◽  
Regional Diversity ◽  
Labor Relationship ◽  
The City

Abstract This article investigates the collective responsibility organizations among boatmen in nineteenth-century Chongqing, when the city became one of the most important metropolises on the southwest Qing frontier. It also introduces two successive turning points in self-organization that were associated with two different classes of boatmen – skippers and sailors. First, in 1803, skippers gained the authority to institutionalize their organizations through their negotiations with the local state regarding official services and service fees. Second, when similar service and fiscal tensions emerged between skippers and sailors in the mid-nineteenth century, the skippers facilitated and supervised the institutionalization of collective responsibility organizations that were run by the sailors themselves. By contextualizing this expansion of collective responsibility organizations within the multilayered interactions between skippers and sailors, this article proposes that the perspective of interclass networks is crucial for deepening the study of state−society interactions, the capital−labor relationship, as well as the tension between imperial integration and regional diversity in early modern China.

Apparent Velocity of Motion Aftereffects in Central and Peripheral Vision

Perception ◽  
1986 ◽  
Vol 15 (5) ◽  
pp. 603-612 ◽  
Author(s):  
Michael J Wright
Keyword(s):  
Visual Field ◽  
Time Course ◽  
Peripheral Vision ◽  
Temporal Frequency ◽  
Motion Aftereffect ◽  
Apparent Velocity ◽  
Real Motion ◽  
Temporal Decay ◽  
Spatial Grain ◽  
Motion Aftereffects

Adapting to a drifting grating (temporal frequency 4 Hz, contrast 0.4) in the periphery gave rise to a motion aftereffect (MAE) when the grating was stopped. A standard unadapted foveal grating was matched to the apparent velocity of the MAE, and the matching velocity was approximately constant regardless of the visual field position and spatial frequency of the adapting grating. On the other hand, when the MAE was measured by nulling with real motion of the test grating, nulling velocity was found to increase with eccentricity. The nulling velocity was constant when scaled to compensate for changes in the spatial ‘grain’ of the visual field. Thus apparent velocity of MAE is constant across the visual field, but requires a greater velocity of real motion to cancel it in the periphery. This confirms that the mechanism underlying MAE is spatially-scaled with eccentricity, but temporally homogeneous. A further indication of temporal homogeneity is that when MAE is tracked, by matching or by nulling, the time course of temporal decay of the aftereffect is similar for central and for peripheral stimuli.

Subsampling Herbarium Collections to Assess Geographic Diversity Gradients: A Case Study with Endemic Orchidaceae and Rubiaceae in Cameroon

Biotropica ◽  
2011 ◽  
Vol 44 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Vincent Droissart ◽  
Olivier J. Hardy ◽  
Bonaventure Sonké ◽  
Farid Dahdouh-Guebas ◽  
Tariq Stévart
Keyword(s):  
Diversity Gradients ◽  
Geographic Diversity ◽  
Herbarium Collections

scholarly journals Latitudinal Diversity Gradients in New World Bats: Are They a Consequence of Niche Conservatism?

PLoS ONE ◽  
2013 ◽  
Vol 8 (7) ◽  
pp. e69245 ◽  
Author(s):  
Maria João Ramos Pereira ◽  
Jorge M. Palmeirim
Keyword(s):  
New World ◽  
Niche Conservatism ◽  
Diversity Gradients

Gradients in regional diversity of freshwater taxa

2009 ◽  
Vol 28 (2) ◽  
pp. 504-514 ◽  
Author(s):  
Richard G. Pearson ◽  
Luz Boyero
Keyword(s):  
Regional Diversity
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