Post on 12-Jan-2016
Unit 12Adaptation & Natural
Selection
Pre-Assessment1. A man becomes a fireman. While
working at his job, he grows strong and his muscles get big due to the physical work. When this man has children, can we predict that they will also have big muscles since their dad does? Why or why not?
2. Describe/discuss an example of an adaptation.
What is a trait?
A characteristic that describes an organism.
Where do we get our traits?
DNA!Genes!
Variation• A distinct feature (trait), behavior, or
physiology of the organism that occurs to individuals within a population or species
Population• Members of the same species that live in the
same geographical area• May be distinctly different than populations
living elsewhere, due to the spread of local adaptations within a population
Adaptation• A process by which a population becomes
better suited to its habitat• A genetic variation that provides an advantage
to survive and reproduce
Examples of Adaptations• Mimicry of leaves by insects is an adaptation for evading predators• Echolocation in bats is an adaptation for
catching insects.• A plant storing food in the form of
a bulb
Examples of Adaptations
• Birds migrating to a different geographical or climatic region where food is more available• A bear hibernating to survive long periods of cold temperature or reduced food supplies• A walrus uses blubber to store energy and
keep warm
What trait keeps this organism safe?
Camouflage!
Camouflage allows an organism to
blend in by changing the pattern/color of
their skin.
What trait keeps this organism safe?
Barbs!
Barbs keep this organism safe
from predators that want to eat
it.
What trait attracts bees to this plant?
Color!Scent!
Patterns!
Flowers look & smell pretty to attract bees!
Why do these bugs have different mouthparts?
They are adapted to the insect’s method for eating!
Natural Selection• Process of selection whereby favorable traits
become more common and less favorable traits become less common in following generations
• Evolution results from natural selection acting upon variation within a population
Natural Selection• Environmental changes can influence natural
selection• Individual organisms with advantageous traits
are more likely to survive and have offspring
Natural SelectionFactors that affect natural selection• Overproduction of offspring in a species• Competition between species• Genetic variations within a population
Big Question
Why do these dogs look so different?
Selective Breeding!
Humans select the traits they like & only bred dogs
that have those traits.
• After a few generations of puppies, all the dogs they own have those traits!