Natural Selection

Natural Selection: A process by which characteristics that make an individual better suited to it's environment become more common in the species. Sometimes referred to as “survival of the fittest”

How Does Natural Selection work? 1. Those with the unique characteristics best suited for their environment will survive and produce offspring. 2. End result = ADAPTATIONS

English Peppered Moth –Natural selection in action camouflaged moth dark moth - random mutation not as common Soot covered tree England 1800’s

Shell for protection Adaptations Behaviors or physical characteristics that allow organisms to live successfully in their environment Long neck to reach leaves Long shallow roots, needles to protect from animals

Niche An organisms’ role in an ecosystem = niche. Niche and Habitat are different ◦Address of an organism = Habitat ◦“Job” or “Profession” = Niche Habitat = Forest Niche = produce oxygen provide home for birds Organism = tree

Explain why two organisms cannot occupy the same niche: If two species occupy the exact same niche in nature, one will die off due to competition for limited resources.

Video Link – Niche, Competition, Predation, and Symbiosis

Three major types of interactions among organisms: Competition Predation Symbiosis

Competition: The struggle between organisms to survive as they attempt to use the same limited resources.

Predation: An interaction in which one organism kills another for food.

Predator or Prey: Predator - organism that does the killing Prey – organism that is killed.

Effect of predation on population size: What variable is plotted on the x-axis? ______ What two variables are plotted on the y-axis? ________ and __________ years # of moose # of wolves

Effect of predation on population size: How did the moose population change between 1965 and 1972 ___________ How did the wolf population change between 1973 and 1976? __________ It increased

Effect of predation on population size: How might the change in moose population have lead to the change in wolf population? – The wolf preys on the moose so more moose meant more food for the wolf.

Effect of predation on population size: How might disease in the wolf population one year affect the moose population the next year? – Disease in the wolf population might cause some to die. With less predators, the moose population would most likely increase.

Examples of Predator Adaptations Cheetah speed Owl eyes Jelly fish venom

Defense Strategies of Prey Mimicry Protective Covering False Coloring Warning color Camouflage

Video Link on Predator and Prey Interactions

Interactions – Three Types

Symbiosis – a close relationship in nature that benefits at least one species Termites Bacteria from gut of termite

Symbiosis

Mutualism Both species benefit

Commensalism One species benefits, but the other isn’t harmed or helped.

Parasitism One species benefits and the other is harmed. The one benefiting is the parasite The one being harmed is a host