Group: Savage Lab, UCLA - with tag environment [10 articles]

Abstract

A theory for the expression of a population's response to density-independent gradients of environmental factors is derived for the case of asexuality. It is shown that the environmental tolerance of a genotype is a function of at least four parameters: g$_1$ and V$_E1$, the environmental optimum and its developmental variance between individuals, and g$_2$ and V$_E2$, the expected genetic contribution to the breadth of adaptation and its developmental variance. The realized breadth of adaptation of a genotype (V$^1/2$) is a complex ...

Abstract

Very few ecological studies have attempted to fully test the integrative role of abiotic and biotic factors in interspecific interactions. There is little if any dispute about the value of such an approach in community ecology. However, there is great disagreement over the present direction of the field; we advocate a reemphasis of the integrative role of abiotic and biotic factors. By using literature examples and data on the role of salinity in reversing the competitive relations between fish of the ...

Abstract

Many basic biological functions are constrained by the physical properties of the fluids in which organisms live. Here I explore four selected examples in which physical differences between air and water have contributed to the functional divergence of terrestrial and aquatic organisms. 1. Water is about 800 times as dense as air. As a result, while the cost of locomotion is generally less for aquatic organisms, the hydrodynamic forces they encounter are larger. 2. The combined effects of density and viscosity ...

Abstract

10.1126/science.277.5325.500 ...

Abstract

We examined the linkage between climate and interspecific plant interactions in New England salt marshes. Because harsh edaphic conditions in marshes can be ameliorated by neighboring plants, plant neighbors can have net competitive or facilitative interactions, depending on ambient physical stresses. In particular, high soil salinities, which are largely controlled by solar radiation and the evaporation of marsh porewater, can be ameliorated by plant neighbors under stressful conditions leading to facilitative interactions. Under less stressful edaphic conditions, these same neighbors may ...

Abstract

Community assembly processes are thought to shape the mean, spread, and spacing of functional trait values within communities. Two broad categories of assembly processes have been proposed: first, a habitat filter that restricts the range of viable strategies and second, a partitioning of microsites and/or resources that leads to a limit to the similarity of coexisting species. The strength of both processes may be dependent on conditions at a particular site and may change along an abiotic gradient. We sampled environmental variables ...

Abstract

Depending on the wind regime, sand dunes exhibit linear, crescent-shaped or star-like forms resulting from the interaction between dune morphology and sand transport. Small-scale dunes form by destabilization of the sand bed with a wavelength (a few tens of metres) determined by the sand transport saturation length. The mechanisms controlling the formation of giant dunes, and in particular accounting for their typical time and length scales, have remained unknown. Using a combination of field measurements and aerodynamic calculations, we show here ...