How Organisms Interact in Communities

Objectives Describe coevolution Predict how coevolution can affect interactions between species Identify the distinguishing features of symbiotic relationship

Interactions Among Species Some interactions among species are the result of a long evolutionary history is which many of the participants adjust to one another over time Coevolution: back and forth evolutionary adjustments between interacting members of a community

Predators and Prey Coevolve Predation: the act of one organism killing another for food Predator: the organism that captures the prey Prey: the organism that gets captured

Predators and Prey Coevolve Parasitism: one organism feeds on and usually lives on or in another, typically larger organisms They do not usually kill their prey (host) Depend on host for food and place to live and for reproduction

Plant Defenses Against Herbivores Protect themselves with thorns, spines, and prickles Chemical compounds that discourage herbivores Secondary compounds: virtually all plants contain these defensive compounds All plants make their own unique defense chemical

How Herbivores Overcome Plant Defenses Certain herbivores are able to feed on plants that are protected by chemical defenses Adaptations to these chemical defenses

Symbiotic Species Symbiosis: two or more species live together in a close, long-term association Symbiotic relationships can be: Beneficial to both Benefit one organism and leave the other harmed or unaffected

Mutualism Mutualism: symbiotic relationship in which both participating species benefit Ex. Ants and aphids

Commensalism Commensalism: symbiotic relationship in which one species benefits and the other is neither harmed nor helped Sea anemones and clown fish

Review Describe coevolution Predict how coevolution can affect interactions between species Identify the distinguishing features of symbiotic relationship Symbiosis Mutualism Commensalism