Community Interactions Ecology Community Interactions

Objectives Compare and Contrast interspecific and intraspecific competition. Describe three types of symbiosis.

Standard The following standards will be addressed: B-6.1

KEY CONCEPT Organisms interact as individuals and as populations.

Community Interactions Some species enhance their chance of survival by forming relationships with other species. Types: 1) Competition 2) Predation 3) Symbiotic Relationships

Competition and predation are two important ways in which organisms interact. Competition occurs when two organisms fight for the same limited resource. Intraspecific competition Interspecific competition

Competition Interspecific competition occurs when organisms of different species attempt to use an ecological resource in the same place at the same time. Intraspecific competion is when organisms of the same species attempt to use a resource at the same time.

Adaptations to Avoid Competition Reduce niche size Natural selection among organisms Character displacement Example: Finches on Galapagos Islands all eat the seeds from the small variety of plants on the islands, but the bird’s beak size determines the size of the seed that it can eat. This allows others to eat the seeds as well, just of different sizes. Immigration and Emigration of organisms Resource partitioning Using only a part of a resource; sharing

Predation occurs when one organism captures and eats another.

Adaptations to Avoid Predation Animal Adaptations Some organisms flee when a predator arrives. Some use mimicry or camouflage. Some use deceptive markings such as fake eyes. Some produce toxins. Plant Adaptations Plants cannot run away from predators. Some have sharp thorns, spines, sticky hairs, and tough leaves. Some have chemical defenses which are poisonous to predators.

Community Interactions A symbiotic relationship is one in which two organisms live together (symbiosis) There are 3 types of symbiotic relationships: Mutualism Commensalism Parasitism

There are three major types of symbiotic relationships. Mutualism: both organisms benefit

There are three major types of symbiotic relationships. Commensalism: one organism benefits, the other is unharmed Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Organism benefits Ø Organism is not affected Commensalism

There are three major types of symbiotic relationships. Parasitism: one organism benefits, the other is harmed Organism benefits _ Organism is not affected Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. Parasitism +

There are three major types of symbiotic relationships. Parasitism meet their needs as ectoparasites (such as leeches) and endoparasites (such as hookworms)