Food partitioning and community organization in a mountain lizard guild of Northern Mexico.

Food niche relationships among four sympatric Sceloporus species were studied in the Sierra Madre Occidental, N.E. Mexico. Although some very high food-niche overlap values were observed, this does not prove that interspecific competition is currently important in organizing this lizard assemblage. Moreover, explaining habitat segregation among the coexisting species as an ecological result of interspecific competitive pressure is unlikely: the overall ecology and behaviour of these species is too much dependent on their microhabitat or substrate specialization to allow such an exclusive interpretation. Thus, this community is probably not mainly organized by species interactions but rather through the specific ecological needs of each species.