Download Principles of Evolution What is evolution?

Principles of Evolution
What is evolution?
The accumulation of inherited changes
within a POPULATION over time.
Population: group of individuals of 1 species
that live in the same geographic area at the
same time.
Species: organisms with similar structures,
function & behavior that can interbreed.
How do we know thing have
changed?
Fossils
Remains of
dead organisms
which are
preserved in
rock
Fossils develop in different ways.
Uniformitarianism
The hypothesis that
the earth developed
slowly through
natural processes.
Index Fossils
Certain organisms that
characterize a large
geographical area.
Index Fossils
Use fossil layers to date rocks: index fossils
Other ways to date fossils
Radioisotopes
Emit radiation & change into different elements as
they decay
Radioactive Decay
Break down of radioisotope
Uranium – 235 = Lead – 207
Half Life
Time required for ½ an atom of radioisotope to
change into a different atom
Jean Baptiste Lamarck
Developed the hypothesis of
“Inheritance of Acquired
Characteristics”
This hypothesis stated that parents
could pass along their acquired
characteristics to their off spring.
Could this work?
Jean Baptiste de Lamarcke: Arranged all
animals in a graduated sequence, beginning
with mammals and working in order of
decreasing complexity to to reptiles, fish,
invertebrates, and eventually down to the
polyps. This hierarchy represented the
sequence of evolution, beginning with the
simplest animals and proceeding, through
small modifications, to produce all animals.
He suggested four laws to explain why and
how animal life might change: 1) The life
force tends to increase the volume of the
body and to enlarge its parts; 2) New
organs can be produced in a body to satisfy
a new need; 3) Organs develop in
proportion to their use; 4) Changes that
occur in the organs of an animal are
transmitted to that animal's progeny.
Males battle for females
Charles Darwin (1809–1882)
One of the best
known figures of
evolution.
His famous trip on
the H.M.S. Beagle
gave him the data
and background to
form his hypothesis.
Darwin
Proposed that all
species currently
living on our
planet arose from
earlier ones by a
process of gradual
evolution.
Natural Selection
The process by which
certain individuals
have traits that make
them more likely to
reproduce.
Natural Selection Modifies
Populations Over Time
Descent with modification.
What does artificial selection
do?
Artificial selection is
human-controlled
breeding that is used to
modify organisms.
These cole crops are all
the same plant species.
Brassica oleracea has
been bred to accentuate
different traits:
Leaves, roots, flowers,
stems
4 Premises of Evolution by
Natural Selection
1. Variation
2. Heredity
3. Differential Reproductive Success
• Limits on Population Growth – Thomas
Malthus
4. Population gene frequecies change
Modern Synthesis (Synthetic
Theory of Evolution)
Combines Darwin’s theory of evolution
by natural selection with modern
genetics.
Genetics explain how populations adapt
to their environment.
5 Biological Measures of
Evolution
1. Homologous Structures.
2. Homoplastic Structures
3. Vestigial Structures
4. Embryological similarity
5. Modern biochemical and genetics
HUMAN
CAT
Humerus
Homologous
Structures
Radius
Ulna
Carpal
Metacarpal
1
1
Phalanges
5
4
3
2
54
3
2
Which of the following structures is NOT
homologous to the others?
1. Alligator forelimb
2. Bird wing
3. Human arm
4. Insect wing
5. Bat wing
Homoplastic Structures
Different structures serve the same function
These structures are known as Analogous
Structures
Convergent Evolution
When populations with separate
ancestors adapt in similar ways to similar
environmental constraints.
Vestigial Structures
The existence of species of flightless birds
with wings suggests that
1. they are not related to flying birds.
2. they are descended from flying birds.
3. they are ancestral to flying birds.
4. they are descended from a different group of
dinosaurs than are flying birds.
5. birds did not evolve from dinosaurs.
Embryonic Development
Vertebrate embryos similar in the 1st stages
Ancestral vertebrates possessed genes that
directed development & genes still present.
Biochemical & Genetic
Relationships
Molecular Structure
Classification
Nucleotide sequences of DNA (aka
genotype) can be used to investigate
relatedness.
DNA sequencing of slow evolving genes works
well for comparing distantly related organisms
Structure of the chromosomes can also be
examined, as well as chromosome number.
The genetic code is common to virtually all
organisms.
Two important points of
evolutionary changes:
1. The variations are produced by chance
mutations.
New variations can be good, bad, or
neutral
2. Natural selection selects for organisms
that are the best adapted to a particular
environment.
Can be bad if environment changes!!!
What are mutations?
Mutations are changes in the DNA
sequence.
Mutations are very rare!!!
Mutations are NOT goal directed.
If mutations are rare, how do
they affect evolution?
Changes in DNA result in a change in the
genes that are expressed in an organism.
New genes allow for new variations in a
population on which evolution can work.
Antibiotic Resistance Evolves
by Natural Selection
Some strains of bacteria are naturally
resistant to antibiotics
Natural selection acts on individuals, while
populations are changed by evolution.
Evolution is a change in the genetic makeup of a population. (NOT SPECIES!)
Evolution is not always good or beneficial
Most commercial pesticides are effective
for only 2-3 years. This is because
1. new pests invade the area.
2. the chemicals induce mutations that
convey immunity.
3. the chemicals mutate.
4. the pests learn to ignore the chemicals.
5. those pests with advantageous mutations
will survive and reproduce.
Evolutionary (Phylogenetic)
Trees
Used to show relatedness between groups
(or individuals) of living things
Common ancestor
(A and B)
Common ancestor
(A, B and C)
Phylogenetic Trees
Most trees are MONOPHYLETIC
Monophyletic Trees contain all of the
living descendants of a common ancestor.
Exception to Monophyletic Tree
Reptiles aren’t monophyletic, because their current
classification does not include the birds.
Key Terms
Taxonomy:
science of "naming" organisms based upon relatedness
Evolutionary Taxonomy:
individual characteristics were used to determine
relatedness
Cladistics:
classes of characteristics (shared derived features) are
used to determine relatedness
Cladistics
Why aren’t reptiles considered to have a
monophyletic grouping?
1. There is more than one type of reptile.
2. Crocodiles and turtles are not from the
same ancestor.
3. They do not contain birds, which are from
the same ancestor.
4. They do not contain frogs, which are from
the same ancestor.
5. Nobody likes reptiles.
Some Applications of Evolution
Agriculture: evolution of pesticide resistance in
insects and other pests
Medicine: rapid evolution of disease-causing
bacteria and viruses
Conservation management: uses evolutionary
principles of population genetics for rare and
endangered species
Bioremediation: evolution of oil-eating microorganisms in that can be used for clean-up
after oil spills