Transcript DNA & PROTEIN SYNTHESIS

EVOLUTION
Jean Baptiste Lamarck
- One of the first to propose a
hypothesis for how species can
change.
“Theory of Acquired Characteristics”
- If an organism used a part
of its body more, it grew
bigger (or changed).
- Any learned / acquired traits
are then immediately passed
on to their offspring.
Charles Darwin
- Developed his ideas based on his 5
year voyage as a naturalist aboard the
HMS Beagle.
- Wrote the book:
On the Origin of Species
- Discovered more than 1500
species on the
Galapagos Islands.
* What is a species?
- Darwin’s Observations:
* Noticed only slight differences
between species on each island.
- Adaptations:
A trait which allows an
organism to survive in
its environment.
* Could be anything!
What can you say
about each
tortoise’s food
supply?
- Darwin’s Theories:
1. Natural Selection
- When an individual(s), best suited
for its environment, survives, mates
& pass on its genes.
Factors Involved/Needed:
- Overproduction
- Variation
- Competition
- Those who can’t
survive, die.
2. Artificial Selection
- When a breeder selects which traits
are desirable, not the environment.
3. Survival of the Fittest
- Who is the most fit?
- The one’s who survive to produce
the most “fertile” offspring.
III. Evidence for Evolution
A. Fossil Evidence
- What is a fossil?
* Trace of a long dead organism.
- How do they form?
* Organism dies and is quickly
buried by sediment.
- How old they are?
1. Relative Dating
2. Absolute Dating (Half-Life)
- Types of Fossils:
1. Petrified
- Bone that has been changed to rock.
2. Molds & Casts
- Molds are hollow spaces in sediment.
- Casts are molds filled in with sediment.
3. Preserved Remains
- Organisms which have become fully
preserved in materials such as ice or
tree sap.
B. Homologous Structures
- Similar anatomical features shared
between multiple species.
Humerus
Radius
Ulna
Carpals &
Metacarpals
Phalanges
C. Analagous Structures
- Different structures, same function.
D. Vestigial Structures
- Features which no longer serve a
purpose.
E. Embryological Structures
- Similarity seen in early fetal
development.
F. Biochemical Evidence
- Similarity in genetic material
between different organisms.
Examples: DNA between Chimps & Humans
Proteins amongst various species
G. Transitional Species
Ex. Archaeopteryx
H. Bacterial Evolution in Action
• Bacteria evolves at such a fast rate due to
it’s short lifespan.
• Many generations can be observed over a
short period of time.
• Antibiotic resistant bacteria
– MRSA
IV. Conditions which affect Gene Frequencies
A. The sum of all genes in a population
is referred to as the Gene Pool.
B. If a population is in equilibrium, it will
not evolve. Gene frequencies are
equal.
C. 5 Factors that Affect Gene Pools:
1. Mutations
- Introduces new alleles
which can spread quickly
if advantageous.
2.
Genetic Drift
- Random changes in allele frequencies.
- Mainly affects small populations.
(Microevolution)
- Can result in the “founder effect.”migration of a small subgroup of a
population.
3.
Gene Flow / Migration
- Genes moving in and out of a
population.
– Immigration- individuals entering a population
– Emigration- ind. leaving a population
4.
Non-Random Mating
- When organisms mate based on specific
traits.
Ex: Height, Strength, Blue Eyes, Skin Color, etc.
5.
Natural Selection
- The environment itself dictates the
change in a population.
Three Types:
a. Stabilizing
- Selects the average traits in a
population.
b. Directional
- Favors one extreme.
c. Disruptive
- Favors both extremes
Single Gene vs Polygenic Traits
• Single gene trait- controlled by a single
gene with 2 alleles.
– You either have it or you don’t.
– Ex- widow’s peak, hitch hiker’s thumb
• Polygenic trait- controlled by 2 or more
genes.
– Ex- height, hair color
V.
Pattern, Speed and Formation of Species
A. Patterns:
* These mainly occur within large
populations (macroevolution).
1. Coevolution
- When two or more species
evolve closely together.
2. Convergent
- The environment selects which traits are
beneficial.
- Dissimilar and/or similar species evolve
similar traits.
3. Divergent
- When two or more related species become
more and more dissimilar.
Two Types:
a. Adaptive Radiation
- When many species evolve from the
same species.
Ex: Galapagos Finches
b. Artificial selection
- When an organism is bred for a
specific trait(s).
Ex: Dogs from grey wolves
B. Formation of New Species (Speciation)
1. Reproductive Isolation- members of a
population can no longer interbreed.
a)
Geographical- When a population evolves
into separate species due to a physical
barrier.
b) Behavioral-
• have ability to interbreed but do not due
to different courtship rituals.
–Ex- Eastern and Western Meadowlark
Reproductive Isolation Cont.
c) Temporal– When species mate at different times.
– Ex- 3 different orchids produce pollen on 3
different days.
C. Speed of Evolution
1. Gradualism
(Macroevolution = Large Populations)
- Speciation over very long periods of
time.
- Usually millions of years.
2. Punctuated Evolution
(Microevolution = Small Populations)
- Speciation occurs quickly
- Can take only hundreds to thousands
of years.