Transcript Evolution and the History of Life

Mr. Tsigaridis
EVOLUTION AND THE
HISTORY OF LIFE
PART 3
Natural
Selection
Darwin theorized that evolution occurs through a process
he called natural selection
Overproduction– Each species produces more
1. ______________
offspring that will naturally survive.
Genetic Variation
2. ______________
– individuals will be slightly
different from one another.
3. ____________
– competition for resources
Survival Struggle
Abiotic and Biotic factors
Successful Reproduction
4. ___________________
– fitness
(Survival of the fittest)
Genetic Variation
Two important words:
1. Genotype: The actual genetic code of an individual’s
DNA.
2. Phenotype: The physical characteristics of an
individual.
Genotype versus Phenotype
In many cases the phenotype is dominated by the
genotype.
In other cases, the environment exerts strong controls
on the outward appearance of an organism. There
might be the genetic potential, but it is not
expressed.
Thus, in general the phenotype represents some
combination of genetic and environmental factors.
Chapter 8.3 Natural Selection in
Action
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Insecticide Resistance
Adaptation to Pollution
Formation of New Species
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Separation
Adaptation
Division
Insecticide Resistance
 Insects that cause economic or health damage are
becoming more difficult to kill due to insecticide
resistances.
 Insecticides are compounds designed to kill insects
(cidal – to kill).
 Insects that are resistant to a particular insecticide
can survive and reproduce while those that do not
have the genotype that infers resistance will die and
will not reproduce.
Resistance
 The application of the harmful material (by humans)
results in an artificial selection for those insects that are
resistance.
 The same, unfortunately occurs to disease causing
bacteria and virus, creating “super bugs” which often
times results in incurable situations or death because
antibiotics (against life) are no longer effective.
 This is why it is so important when prescribed an
antibiotic to complete the treatment to avoid mutation
during treatment of a pathogen creating a resistant
pathogen that can survive – generation times of bacteria
and virus is measured in minutes.
Adaptation to Pollution
 Peppered moths are the classic case.
 Dark moths were low in population because they
did not blend well with the environment and so
where eaten by predators. The pale moths were
high in population because they were
camouflaged.
 Then comes along the Industrial Revolution with
coal burning to fuel factory machines and heat
homes. The results of burning coal are
sooty smoke, acid rain, and mercury
contamination.
 Well, the sooty smoke coated the
vegetation made those pale moths
stand out like a sore thumb and the
dark moths became camouflaged. So
what do you think happened?
 The population of dark moths
increased and the population of pale
moths decreased.
Match each statement about the peppered moth
population (1-4) with the appropriate step in
1. Moths
that live
to
a. Genetic
natural
selection
(a-d).
maturity may mate and
variation
produce offspring.
2. A population of peppered b. Successful
reproduction
A moths contains some
light-colored moths and
some dark-colored moths.
c. Overproduction
D 3. Many moths do not
survive because they are
eaten by birds.
C 4. Peppered moths lay many d. Struggle to
eggs.
survive
B
Formation of New Species
Steps: Separation, Adaptation, Division (speciation).
 Separation allows the gene pool to be come isolated
where no mixing of the populations occur.
 Adaptation are mutations that help the species to be
successful in the new environment.
 Division occurs over time these mutant changes
result in a separate species that cannot interbreed,
speciation.
Chapter 8 Review
 One species evolves into another through the
speciation
process of _____________________.
 A group of similar organisms that can mate with
one another to produce fertile offspring is known
as ________________. species
adaptationhelps an organism survive better
 A(n) __________
it its environment.
Evolution
 ____________is
the process by which populations
change over time
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Artificial selection
In ______________________________,
humans select
traits that will be passed from one generation to
another.
A change in a gene at the DNA level is called a
Mutation
__________________.
The theory of evolution combines the principles of
Natural selection
and
_________________________
__________________.
genetic
inheritance
The
fact that
all organisms have DNA as their genetic
material is evidence that all organisms ______
__________________________. Everything had to
desended
from a common ancestor.
start
somewhere.