Community Ecology Chapter 20 Biology 138

Species Interactions Five major types of interactions or symbioses. 1. Predation 2. Parasitism 3. Competition 4. Mutualism 5. Commensalism

Predation Predators vs. Prey -Regulates population size. -Adaptations lead to natural selection. -Survival…carry on the species! Defense Mechanisms: Mimicry Camouflage Physical Defenses Secondary Compounds (Poisonous)

Which snake is poisonous? The nonvenomous Sinaloan milk snake (right), for example, closely mimics the color pattern of the venomous coral snake.

Polyohemus Moth mimics an owl.

Competition Principle of Competitive Exclusion --- Local extinction of a species due to competition Character Displacement --- Evolution of differences between body parts which reduces competition between similar species Resource Partitioning --- Competition is intense between closely related species because they require the same resources. So when they coexist, each species only uses part of the available resources.

Last Types of Symbiosis Mutualism: Both species benefit. Commensalism: One species benefits, the other is not affected. Parasitism: Parasite vs. Host Ectoparasites vs. Endoparasites