Wildlife Ecology: Understanding Niches and Competition for Resources - Prof. Eric M. Schau, Study notes of Zoology

Download Wildlife Ecology: Understanding Niches and Competition for Resources - Prof. Eric M. Schau and more Study notes Zoology in PDF only on Docsity! 1 Wildlife Ecology • Range of resources and conditions over which an organism can successfully survive and reproduce AND • The methods it uses to acquire resources = “address” + “profession” Page 2 Niche • Fundamental niche: maximum range of resources, conditions, and methods where an organism could potentially be successful • Realized niche: resources, conditions, and methods actually used by the organism – Why? Page 3 Niche Page 4 SU C C ES S RESOURCE OR CONDITION GRADIENT Eury- (wide) SU C C ES S RESOURCE OR CONDITION GRADIENT Steno- (narrow) Niche • G.E. Hutchinson: Niche = n-dimensional hypervolume • Each dimension represents a resource or condition – food, water, cover, space, temperature Page 5 Niche: 2-D Temperature M oi st ur e Species 1 Species 2 • “the resources and conditions present in an area that produce occupancy – including survival and reproduction – by a given organism” – Hall et al. 1997 cited in Bolen &Robinson Page 6 Habitat 2 • Competition: When two or more organisms both exploit the same limited resource – intensity determined by niche overlap Modes of Competition Scramble competition: each individual uses resources without regard to other individuals Interference competition: some individuals restrict access to resources by others How? CONCEPTS Competitive exclusion principle: two species that depend on the same limiting resource often cannot coexist Resource Partitioning: restriction of the realized niche in the presence of a competitor to reduce niche overlap Competition and Management Question: Do cattle compete with mule deer and elk in Oregon? Stewart et al. 2002. Journal of Mammalogy 83:229-244