14.1 KEY CONCEPT Every organism has a habitat and a niche.

Habitat vs Niche A habitat is all aspects of the area in which an organism lives. biotic factors abiotic factors An ecological niche is how a species obtains the resources it needs for its survival. –food –abiotic conditions –behavior Habitat = where a species lives Niche = how it lives within its habitat

Resource availability gives structure to a community. Species can share habitats and resources. Competition occurs when two species use resources in the same way. Competitive exclusion keeps two species from occupying the same niche.

Competitive exclusion has different outcomes. –Two outcomes: 1. Niche Partitioning 2. Evolutionary Response –Divergence –Indicates Coevolution

Ecological Equivalents Ecological equivalents are species that occupy similar niches but live in different geographical regions. Convergent Evolution Madagascar - Mantella South America - Dart

14.2 KEY CONCEPT Organisms interact as individuals and as populations.

Competition and Predation Competition occurs when two organisms fight for the same limited resource. Intraspecific competition Same Species Interspecific competition Different Species

Predation occurs when one organism captures and eats another.

Symbiosis: a close ecological relationship between two or more organisms of different species that live in direct contact with one another. Three Types: 1. Mutualism – both organisms benefit Ex: Bat and Cactus

Nitrogen Fixing Bacteria (+) Legumes (+)

Fungi (+) Plants (+)

2. 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 Organism is not affected Commensalism

Whales (0) Barnacles (+)

3. Parasitism: one organism benefits, the other is harmed Organism benefits + _ Organism is harmed Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Braconid wasp Braconid wasp lays its eggs inside a caterpillar. When the larvae hatch, they eat the caterpillar from the inside out, consuming nutrients they need to become an adult. _ Parasitism + +

Types of Parasites: 1. Ectoparasites (such as leeches) 2. Endoparasites (such as tapeworms)