Download Adaption Variation and Natural Selection

March 27TH
 An adaptation is a structure, behavior or
physiological process
 These help an organism to survive and
reproduce in particular environment
 Example: camouflage/mimicry
 Can you find the “hidden organisms” in the
following slide?
Mimicry (mimic
environment)/Camouflage
 Biochemical and Body
Processes
 Hibernation in ground
squirrel
 Structural Adaptation
 Sharp talons and
excellent vision of owl
 Thick leaves of buffalo
berry that help to reduce
the water loss on hot
summer days
Adaptation
• Different kinds of teeth for
different animals, say carnivore
ripping teeth and herbivore
grinding teeth
• Different tissues within species
Heart vs. eye etc.
They are a result of a gradual change of
characteristics over time
A variation that helps an individual in a
population is likely to be passed on
from survivor to survivor
Some variations help and some do not,
not all variations become adaptations!
Let’s Look at Our Variations!
 Question: Are there measureable differences in sizes
among individuals of a species?
 Two students from each table, measure your thumb
and your middle finger
 Collect the data and graph this information
 Draw a data table and a bar graph that best suits the
data gathered
 Conclude what you see with this data
 A group of reproductively compatible populations
How does variation
within a species
occur?
 Organisms that reproduce sexually have a blueprint
from both parents
 Through this reproduction, particular traits are passed
on to the new organisms
 Mutations are genetic changes that happen in DNA
 Occur from mistakes that happen when DNA is being
copied
Natural Selection:
It is the production of variations due to:
Mutations: Changes in the DNA
Random mate selection & fertilization
Do we see variation within different wild species ?
Natural Selection
 Individuals with favorable traits are more
likely to leave more offspring better suited for
their environment.
 Example:
English peppered moth (Biston betularia)
- light and dark phases
Humans select traits for dogs, pigeons and other animals when they breed them
(we call this ARTIFICIAL SELECTION).
Bred dogs came from a single original species
NOBODY!!
There is no agent involved in natural
selection.
Natural selection is a process of
elimination
INDIVIDUALS THAT HAVE TRAITS THAT ARE BEST ADAPTED FOR
THE CURRENT ENVIRONMENT ARE THE ONES THAT SURVIVE
TO BREED AND PASS ON THEIR GENES TO THE NEXT
GENERATION.
Organisms not possessing the beneficial traits
either die or don’t have as many offspring.
Natural Selection is Survival of the
fittest