Chapter 11 Section 3 Interactions Among Living Things

Adapting to the Environment Natural Selection – a characteristic that makes an individual better suited for its environment – Survival of the Fittest Adaptations – the results of natural selection – The behaviors and physical traits that allow organisms to live successfully in their environments

Adapting to the Environment Niche – the role of an organism in its habitat, or how it makes its living – Type of food organism eats – How it obtains its food – When and how organism reproduces – Physical conditions needed to survive

Interactions 3 Major Types – Competition – Predation – Symbiosis

Competition Definition: the struggle between organisms to survive as they attempt to use the same limited resource If 2 species occupy the same niche, one of them will eventually die off

Predation Definition: interaction where one organism kills another organism for food Prey = species that is being killed Predator = species that is doing the killing Predation can have a major effect on population size Populations of predators and their prey rise and fall in cycles

Predator Adaptations: Predators have adaptations that help them catch and kill their prey Prey Adaptations: Prey species have adaptations that help them reduce the chance of being caught and killed

Symbiosis Definition: a close relationship between 2 species that benefits at least 1 of them 3 Types of Symbiotic Relationships – Mutualism – Commensalism – Parasitism

Mutualism Relationship where both species benefit is called mutualism – Example: long eared bats and saguaro

Commensalism Relationship where one species benefits and the other species is neither helped nor harmed. Example: Hawks and Saguaro

Parasitism One organism lives on or inside another organism and harms it (but doesn’t usually kill it) Parasite = organism that benefits Host = organism that is harmed Example = Tapeworms and dogs; Ticks and dogs