Sentence examples for passage barriers from inspiring English sources

have been excluded from large portions of historically accessible habitats in the western United States, either by passage barriers or by large-scale changes in habitat quality.

In this light, the second potential effect of passage barriers, the disruption of connections among local populations, is probably much more important.

Passage barriers have two effects that can create important evolutionary consequences even in the absence of any direct changes in selective regime.

While this example might be an extreme one, it is not unique, and the genetic effects of habitat loss and passage barriers deserve greater attention.

There is extensive evidence that formerly anadromous populations of O. mykiss have residualized and become established as residents above passage barriers in California rivers (Gall and Bentley 1990).

The problem can be exacerbated if there are local population extinctions and passage barriers restrict the number of populations from which recolonizing individuals are drawn (Slatkin 1987; Whitlock and Barton 1997; Waples 2002).

In recent years, fishways have increasingly been designed and installed with the intention to not only provide economically important fishes, such as salmonids, with free passage at barriers, but also for other elements of the migratory fish community.

Allowing passage over barriers could provide M. australasica populations with access to additional spawning habitat and enhance recruitment success.

Stephen G. Carrellas, state coordinator of the National Motorists Association, said a high-speed entry system for E-ZPass users was a good idea If fact, Mr. Carrellas said, if more than two-thirds of the state's motorists had the electronic cards in their cars that allowed equipment to record their passage, most toll barriers could be removed -- a notion that has been discussed for years.

Because thyroid hormone passage across brain barriers is a precondition for its action in the CNS, and because brain is an important target of thyroid hormone action, we investigated the role of transthyretin in mediating thyroid hormone access to and distribution within the brain in a transthyretin-null mouse model system.

Furthermore, energy saving migration strategies should be taken into consideration in the construction of fish ways, where resting pools have been suggested to be of importance, since fish after passage of velocity barriers need to recover from burst swimming [20].