Browsing by Subject "Competition (Biology)"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item A quantitative model of density-dependent habitat selection: integrating isodar and isoleg theories(Texas Tech University, 1998-12) Guthrie, Carla GabrielleNumerous conceptual models have been advanced to explain density-dependent habitat selection, but few models address multiple species interactions and even fewer simulate these phenomena. Moreover, the development of quantitative models that incorporate multiple species interactions is in its infancy with existing models being mostly conceptual and limited in application. Herein, I develop a quantitative, simulation model of habitat selection that includes interspecific interactions. The basic model expresses habitat quality in terms of fitness, represented by per capita growth rates, calculated according to the Lotka-Volterra competition equations. Because fitness is assessed via growth rates, this model provides a more accurate representation of distribution patterns than do current models. The development of this model serves two purposes: (1) to permit the quantification of changes in habitat use as a result of intraspecific and interspecific competition, and (2) to unify aspects of habitat selection theory into a general model. In so doing, this model serves as a heuristic device for visualizing isoleg theory, a central theorem of density-dependent habitat selection incorporating interspecific competition (Rosenzweig 1981). Additionally, this model synthesizes two contemporary theories describing habitat selection among competitors; isodar theory (intraspecific competition; Morris 1988) and isoleg theory. Thus, the model explores the combined effects of intra- and interspecific competition, species-specific ecological preferences, and population regulation on species coexistence.Item Competition among five species of cave associated salamanders (family Plethodontidae)(Texas Tech University, 1980-05) Rudolph, Daniel Craig.Item Competition and the structure of small mammal communities(Texas Tech University, 1981-12) Hallett, James GeorgeNot availableItem Coyote (Canis latrans) diet in the Blue Range Recovery Area, Arizona and New Mexico(Texas Tech University, 2004-05) Carrera-Trevino, RogelioControl and extermination of wolves (Canis lupus) in North America has been associated with a coyote (Canis latrans) range expansion. With the natural recolonization and wolf reintroduction programs during the last few decades in some areas, wolves have eliminated coyotes. In other areas, coyotes maintain high densities in the presence of moderate wolf densities. Interactions between wolves and coyotes can have significant impacts on their distribution and abundance. The purpose of this study was to describe the coyote diet and compare it to the diet of the recently reintroduced Mexican wolf in Arizona and New Mexico. Scats were collected from April 1998 through October 2001, in an opportunistic sampling strategy. Scats were broken apart by hand and undigested parts of food items were separated and identified with the aid of a reference collection. We found that coyote diet was composed mostly of mammalian species followed by vegetation and insects. Elk was the most common food item found in coyote scats. Mexican wolf diet had a higher proportion of large mammals and less small mammals than coyote diet did; however, elk was also the most common food item found in Mexican wolf scats. Our results suggest that Mexican wolf diet although different from coyote diet, had less large mammals and more small mammals and was more similar to coyote's diet than previously reported. Considering results in other areas, we could expect that Mexican wolves will have a negative impact on coyotes.