scholarly journals HABITAT SELECTION BY GRAZING ANIMALS IN HETEROGENEOUS ENVIRONMENTS: THE CASE OF HILL SHEEP IN WESTERN IRELAND

2012 ◽  
Vol 112B (3) ◽  
pp. 267-283
Author(s):  
Bryony Williams ◽  
Sean Walls ◽  
Michael Walsh ◽  
Mike Gormally
Oikos ◽  
2009 ◽  
Vol 118 (5) ◽  
pp. 663-674 ◽  
Author(s):  
Jean-Baptiste Mihoub ◽  
Pascaline Le Gouar ◽  
François Sarrazin

2011 ◽  
Vol 32 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Gerardo Leynaud ◽  
Julián Lescano ◽  
Laura Pereyra

AbstractDifferences among wetlands can have important consequences on reproductive success of amphibians; therefore habitat selection is expected to be of particular importance for anurans inhabiting heterogeneous environments. To investigate if the red-belly toad (Melanophryniscus stelzneri; Anura: Bufonidae) uses available habitats differentially and to determine the main factors influencing the use of certain water bodies as breeding habitat, we surveyed 30 spawning sites used by red-belly toads, and 30 adjacent unused sites, in an area of the Sierras of Córdoba, Argentina. We evaluated the relative importance of morphological and biotic features of ponds, and the presence of other organisms within the water body on the use of ponds as breeding sites by red-belly toads. Eight habitat variables related to important water body features were recorded and were used to fit a habitat selection model with GLM. Red-belly toads presented a positive selection to mallines, a wetland characteristic of the Sierras of Córdoba. They were associated with small, shallow ephemeral ponds with muddy banks and a high percent of vegetation cover. In general, the ponds used did not host other anuran species or potential predators. Breeding site selection by red-belly toads is largely consistent with records for other species of the genus in other parts of Argentina.


Ecology ◽  
1980 ◽  
Vol 61 (4) ◽  
pp. 859-867 ◽  
Author(s):  
Robert F. Denno ◽  
Michael J. Raupp ◽  
Douglas W. Tallamy ◽  
Charles F. Reichelderfer

2008 ◽  
Vol 54 (3-4) ◽  
pp. 311-328 ◽  
Author(s):  
Daniel Fortin ◽  
Douglas W. Morris ◽  
Philip D. McLoughlin

Genetics ◽  
1976 ◽  
Vol 83 (4) ◽  
pp. 887-894
Author(s):  
Charles E Taylor

ABSTRACT A model of population structure in heterogeneous environments is described and conditions sufficient for maintaining a polymorphism are derived. The absolute fitness of any genotype is regarded as a function of location in the niche space and the population density at that location. Two modes of habitat selection are examined: (1) organisms are distributed uniformly over the environment; and (2) each organism selects to occupy that habitat in which it is most fit ("optimal habitant selection").—Sufficient conditions for maintenance of genetic polymorphisms are derived for both models. In populations which do not practice habitat selection heterozygote superiority averaged over the environment is sufficient to guarantee the existence of polymorphisms. Comparable conditions for populations which practice optimal habitat selection are much less restrictive. If the heterozygotes are superior to one homozygote in any one part of the niche and to the other homozygote in any other part of the niche then a polymorphism will be defined.—A positive correlation between genetic and environmental variation follows from the model with habitat selection, but not from the other. The adaptive significance of polymorphisms thus depends on how animals behave.


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