BIOLOGY AND EVOLUTION:
An Introduction to Heredity
Do Now:
• Based on your homework, turn to a partner and
discuss whether or not you feel that evolution is
valuable or detrimental and why.
 Make a T-Chart discussing both arguments.
Valuable
Unjust
Religion and Science
• Religion is not always in competition with
science…sometimes they work hand-in-hand.
• Evolution is one way of looking at the beginning
of “life,” while many religions suggest alternative
views to these understandings.
• The most current philosophy is that creationism
and the theory of evolution can co-exist—both of
them may suggest the existence of God.
EVOLUTION IS A THEORY.
What does this really mean?
Does this discredit evolution?
What is a Theory?
• In science, a theory is a rigorously tested statement
of general principles that explains observable and
recorded aspects of the world.
• A scientific theory describes a higher level of
understanding that ties "facts" together.
• A scientific theory stands until proven wrong -- it is
never proven correct.
▫ The Darwinian theory of evolution has withstood the
test of time and thousands of scientific experiments;
nothing has disproved it since Darwin first proposed
it more than 150 years ago.
▫ Many scientific advances, in a range of scientific
disciplines including physics, geology, chemistry, and
molecular biology, have supported, refined, and
expanded evolutionary theory far beyond anything
Darwin could have imagined.
What is Evolution…Basically?
1.
Biological evolution refers to the cumulative changes that occur in
a population over time.
2.
These changes are produced at the genetic level as organisms'
genes mutate and/or recombine in different ways during
reproduction and are passed on to future generations.
3.
Sometimes, individuals inherit new characteristics that give them
a survival and reproductive advantage in their local
environments; these characteristics tend to increase in frequency
in the population, while those that are disadvantageous decrease
in frequency.
4.
Non-genetic changes that occur during an organism's life span,
such as increases in muscle mass due to exercise and diet, cannot
be passed on to the next generation and are not examples of
evolution.
Evidence of Evolution
• The Fossil Record –
▫ Example: The fossils we find in rocks formed when the earth was more covered in
ice show organisms better adapted for living in icy conditions.
• DNA—
▫ Example: Humans have 23 pairs of chromosomes, but our closest relatives, the
great apes - chimpanzees, gorillas and orangutans - all have 24 pairs of
chromosomes. One of the pairs of chromosomes in humans is exactly the same as
2 of the chimp chromosomes but fused together.
• Observation—
▫ Evolution is an ongoing process - everything is still evolving and we can see it
evolving.
▫ Example: The bacteria and viruses that make us ill. These organisms live, die and
reproduce so quickly that they evolve extremely quickly, too. Why do we need to
have a new flu vaccination every year? Because the influenza virus evolves. Why
do we need to finish a course of antibiotics if they are prescribed? Because if we
only use half of the antibiotics, we only kill the weakest half of the bacteria making
us ill. The strongest half lives on and reproduces even more (because they won't
have competition from their weaker brethren). We'd be helping the bacteria to
evolve.
The Classification System
• Carolous Linnaeus develops the system of
taxonomy.
▫ Within this system, he creates various taxonomic
categories to classify beings and look at
connections across living things.
▫ He would classify things based on:
1.
2.
3.
Body structure
Body function
Sequence of bodily growth
Humans are Homo (Genus) sapiens (Species).
How Does Evolution Work?
1) How has Mickey Mouse changed?
2) Mickey clearly has evolved. But why? Why did Walt Disney make
this “selection”?
The Father of Evolutionary Theory
Charles Darwin
▫ First Discoveries:
 The observations made on a journey he took
around the world with companion Captain
Fitzroy
 Observed diversity of living creatures and fossils
▫ Natural Selection The process by which forms of life having traits
that better enable them to adapt to specific
environmental pressures, as predators, changes
in climate, or competition for food or mates,
will tend to survive and reproduce in greater
numbers than others of their kind, thus ensuring
the perpetuation of those favorable traits in
succeeding generations.
 As generation succeeds generation, nature selects
the most advantageous variations, and species
evolve.
 “Survival of the fittest”- those who are eliminated
in the struggle for existence are the unfit.
Natural Selection
Green beetles have been
selected against, and brown
beetles have flourished.
• What important traits do
brown beetles have to
protect them from their
environment?
Heredity
• Dominant vs. Recessive
Genes
Heredity
• Co-Dominance
▫ Later studies suggest that some patterns of
inheritance are not so simple. In some cases,
neither allele is dominant, but rather both are codominant.
 Example: Blood Types
 Type A is produced by one allele, Type B is another.
 A Co-Dominant individual will have AB, causing
neither allele to dominate the other.
DEBATE:
Should we naturally select our own
genetic traits?
• Read and take notes on each form of genetic
engineering.
• You may include your own opinion in the
development each side.