Transcript Evolution part 2 notesx

Agents of Change
(Causes of Evolution)
• Selection (Natural or Artificial) – Different
genotypes have different chances to survive and
reproduce
• Mutation – change in DNA can lead to new,
advantageous traits
• Migration – movement of individuals can change
gene pool of a population
• Non-random mating – Sexual selection (bird calls),
Inbreeding (plants)
• Small populations – Experience large changes in
allele frequencies by chance alone
Speciation (How do we get a new species?)
• Usually involves successive change
• Local populations of a species become isolated and more specialized
(adapted)
• Natural selection acts to keep them specialized (different from the larger
population)
• Populations of a species must become reproductively isolated in
order to develop into new species.
Isolating Mechanisms
• Geographical – Organisms
live in separate locations
• Ecological – Organisms can occupy different niches
(ecological roles) in the same environment
Isolating Mechanisms Cont.
• Temporal – Organisms mate
at different times of the day
Behavioral – Organisms may
have different mating
behaviors (rituals)
Isolating Mechanisms Cont.
• Mechanical – Structural differences prevent mating
(flower cross
pollination)
• Even if a hybrid (liger) forms successfully, they are
usually weak and die in nature, as well as being
infertile.
Evolution Evidence:
1. Adaptations
2. Fossils
3. Comparative anatomy
4. Comparative embryology
5. Comparative Biochemistry (DNA
and Proteins)
6. Plate Tectonics
1. Adaptations: features suited to a
particular environment that allow
organisms to survive and reproduce
Inuit people, who live in the
extreme cold of the Arctic,
have short, stout bodies that
conserve heat.
Masai people,
who live in the
arid lands of
eastern Africa,
have tall, lean
bodies that
disperse heat
well.
Bird Beak Adaptations:
Plant Adaptations:
Help!!!
Venus Fly Trap
• Captures Animals
• Acquires minerals
that it can’t
obtain from
nutrient poor soil
Leaf Adaptations:
Succulents
•Thick
•Store Water
•Prevent
Drying out
Leaf Adaptations:
Pine Needles
• Shed snow
• Less water loss
• Reduced
surface area
• Tolerate wind
Flower Adaptations:
Fly pollination:
• Hair along petals
• Putrid smell
Bee pollination:
• Smooth petal
• Sweet smell
2. Fossil Evidence:
•
Once living remains of
organisms
• Limited
1. Type of material
preserved (bone, shell,
impressions, amber)
2. Incomplete record
3. Easily disrupted
Plant Fossil Evidence:
Dating Fossils
• Relative Age
• describes approximate age of
fossil relative to location.
• Ex. “This fossil is located beneath
that fossil, so it is relatively older.”
• Law of superposition
• Absolute age
• Age of a fossil in years
• Can be calculated using
radioactive dating (ex. Carbon
dating)
• Ex. “This fossil is approximately 1
million years old.”
3. Comparative Anatomy: Structural
similarities link related species
Homologous Structures:
Same underlying structures, different functions,
different environments & common ancestor
Comparative Anatomy Structures:
Analogous:
1. Different ancestors
2. “analogy”=like
3. Different underlying
structures
4. Same Function
5. Similar Environments
6. Convergent Evolution
Homologous:
1. Same ancestor
2. “homo”=same
3. Same underlying
structures
4. Different Functions
5. Different
Environments
6. Divergent Evolution
4. Comparative embryology:
Similar embryo development in closely related species
5.Comparative Biochemistry
• In two related
organisms…
• Similar DNA sequences
• Similar Gene segments
of the DNA
• Code for similar traits
(proteins)
• Closely related
species!
6. Plate Tectonics
• Geological theory:
• Continental masses were one land mass that
explains
• Closely related species have common ancestors
on now separated continents (geographical
isolation)
Final Thought:
• Is it possible to develop an advantageous characteristic within your
own lifetime and pass it on to your offspring?
Explain why or why not.