intraspecific: same species Competition: the active demand for a limiting resource shared by two or more individuals or species intraspecific: same species interspecific: different species Competition does NOT occur in just sharing a resource that is not limiting. interference competition: direct sharing, physical contact exploitative competition: indirect sharing, no physical contact scramble competition: effects of competition equal to all contest competition: effects greater in some than others Ultimate effect is decreased reproductive output, lower fitness

Fig. 12.2 (EFB) Effects on mass

Fig. 11.7 Effects on fecundity

Asymmetric competition

Avoiding Intraspecific Competition Dispersal Movement away from natal environment --allows individuals to reach maximum growth potential, little or no intraspecific competition --how a species with growing populations expands its range to new areas

Costs Associated with Dispersal 1. greater risks, higher mortality --naïve --unfamiliar habitat, cover --where to find food 2. low birth rates (fecundity), at first costs balanced with benefits --selection by fitness levels of dispersers vs. non-dispersers

Helping Behavior in Birds young remain in natal territory for one or more years become ‘helpers’ at parent’s new nest gain experience at raising offspring increase survivorship for breeding > 220 spp. of birds have helpers

Avoiding Intraspecific Competition Dispersal 2. Territoriality Active defense of a resource or space by an individual or group of individuals

Carolina Wren Some territories can be all inclusive, held year-round, to provide food, shelter, nesting space Carolina Wren