G. Shenbrot et B. Krasnov, Habitat selection along an environmental gradient: Theoretical models withan example of Negev Desert rodents, EVOL EC RES, 2(3), 2000, pp. 257-277
We present a set of models of density-dependent habitat selection along an
environmental gradient. The models are based on the assumption of ideal-fre
e distribution and use an approach similar to Morris' isodar analysis techn
ique. It was assumed that habitats along a gradient differ either qualitati
vely (efficiency of resource acquisition) or quantitatively (resource abund
ance) or in both parameters. Depending on the distribution of resource abun
dance and habitat quality along a gradient, the models predict density-inde
pendent or density-dependent habitat distribution with or without density-d
ependent habitat shifts The models were tested using data on a desert roden
t community of the central Negev Desert, Israel. In six of the nine rodent
species (Gerbillus dasyurus, G. gerbillus, G. henleyi, Meriones crassus, Ac
omys cahirinus and A. russatus), direct estimations of habitat breadth and
position fit well the predictions of one of the models based on density rel
ationships. Of these nine species, four (Jaculus jaculus, Gerbillus dasyuru
s, G. gerbillus and Mus musculus) were found to be density-independent habi
tat selectors, four (Meriones crassus, Psammomys obesus, Acomys cahirinus a
nd A. russatus) were density-dependent habitat selectors and one (Gerbillus
henleyi) was a density-independent habitat selector in winter and a densit
y-dependent habitat selector in summer.