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?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 English Peppered Moth –Natural selection in actionselection in action
camouflaged mothdark moth - random mutationnot as common
Soot covered treeEngland 1800’s
Shell for protectionShell for
protection
AdaptationsAdaptationsBehaviors or physical characteristics that
allow organisms to live successfully in their environment
Long neck to reach leavesLong neck to reach leaves
Long shallow roots, needles to protect from
animals
Long shallow roots, needles to protect from
animals
NicheNicheAn 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 Explain why two organisms cannot occupy the same niche: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.
http://www.youtube.com/watch?v=D1aRSeT-mQE
Video Link – Niche, Competition, Predation, and Symbiosis
Three major types of Three major types of interactions among organisms:interactions among organisms:
CompetitionPredationSymbiosis
Competition:Competition:
The struggle between organisms to survive as they attempt to use the same limited resources.
Predator or Prey:Predator or Prey:
Predator - organism that does the killing
Prey – organism that is killed.
Effect of predation on population Effect of predation on population size: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 Effect of predation on population size:size:
How did the moose population change between 1965 and 1972 ___________
How did the wolf population change between 1973 and 1976? __________
It increased
It increased
Effect of predation on population Effect of predation on population size: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 Effect of predation on population size: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 AdaptationsExamples of Predator Adaptations
Cheetah speedOwl eyes Jelly fish venom
Defense Strategies of PreyDefense Strategies of Prey
MimicryProtective Covering False ColoringWarning colorCamouflage
Symbiosis – a close relationship in nature Symbiosis – a close relationship in nature that benefits at least one speciesthat benefits at least one species
Termites
Bacteria from gut of termite