MLK
Fall 2005
M.Elizabeth
www.marric.us/teaching

Darwin theorized that evolution occurs through a process he called natural selection
Overproduction
1.
______________ – Each species produces more offspring that will naturally survive.
2.
______________ – individuals will be slightly different from one another.
3.
____________ – competition for resources
4.
Abiotic and Biotic factors
___________________ – fitness
(Survival of the fittest)

Two important words:
1.
Genotype: The actual genetic code of an individual’s DNA.
2.
Phenotype: The physical characteristics of an individual.

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
• Insecticide Resistance
• Adaptation to Pollution
• Formation of New Species
• 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.

• 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 natural selection (a-d).
B
A
D
C
1. Moths that live to maturity may mate and produce offspring.
2. A population of peppered moths contains some light-colored moths and some dark-colored moths.
3. Many moths do not survive because they are eaten by birds.
4. Peppered moths lay many eggs.
a. Genetic variation b. Successful reproduction c. Overproduction d. Struggle to survive

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.

• One species evolves into another through speciation
•
• A group of similar organisms that can mate offspring is known as ________________.
adaptation species
• survive better it its environment.
____________is the process by which populations change over time

•
Artificial selection 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
Natural selection and
__________________.
• The fact that all organisms have DNA as their genetic material is evidence that all organisms
______ __________________________.
Everything had to start somewhere.