Transcript Evolution and Speciation

 What is Natural Selection?
 What are the mechanisms of Natural Selection?
 How do Beneficial Traits effect Evolution?
 What are some limitations of Natural Selection?
 What are three common myths about Evolution
through Natural Selection?
 Natural Selection is the mechanism of Biological
Evolution.
 Biological Evolution is the process whereby earth’s life
changes over time through changes in the genes of a
population
 Since Early Greek Philosophers, people have tried to
explain the origin of species.
 Charles Darwin and Russel Wallace were the first to
create a credible explanation for the Origin of Species.
 Natural Selection states that since there is a limited
supply of resources needed for survival, there will exist
competition for those resources.
 This Competition will SELECT a natural trait or
adaptation in an organism.
 This organism will survive and pass on its trait to its
offspring, allowing that offspring to have a better
chance for survival.
 Much research and loads of evidence has been found
to support Evolution through Natural Selection.
 Our Six Kingdoms of Life and the Tree of Life stems
from Natural Selection.
 The Fossil Record proves that life existed in ancient
times.
 The Fossil Record though helpful in understanding
Evolution, still has Major Gaps in it and only represents
1% of all species that have ever lived.
 There is still a lot we do not know about the Origin of
Species
 Darwin and Russel created their theory of Evolution
without the knowledge of DNA and heredity.
 Natural Selection involves changes in a population’s
genetic makeup through successive generation.
 Populations, not individuals, evolve by becoming
genetically different.
 Genetic Variability starts with a mutation.
 Mutations are random changes in the structure or
number of DNA molecules in a cell that can be inherited
by offspring.
 Mutations can be triggered by exposure to UV rays,
natural mistakes caused by replication and mutagens.
 Mutations are not malignant in nature. The
environment chooses whether a mutation is beneficial
or not.
 The Environment chooses Mutations that will help
individuals survive and produce offspring.
 A Beneficial Mutation is considered an Adaptation or
Adaptive Trait.
 For Natural Selection to occur, a trait must be
heritable.
 In order for Natural Selection to Occur that inheritable
trait must lead to differential reproduction.
Natural Selection Acts on Individuals
 Genetic Resistance is the ability of one or more
organisms in a population to tolerate a chemical
designed to kill it.
 Antibacterial Resistance
 Pesticide Resistance
 Herbicide Resistance
Natural Selection Acts on Individuals
 Natural Selection acts on the individual while
Populations Evolve.
 In other words, when genes change and mutate and give
an individual in a population a better chance for
survival, Evolution will occur.
 When Environmental Conditions change there are
three responses an organism can have:
 Adapt to the new conditions
 Migrate to a new area
 Become Extinct
Limitations of Natural Selection
 Change in Environmental Conditions can lead to such
an adaptation only for genetic traits already present in
a population’s gene pool or for traits resulting from
mutations.
 Reproductive Capacity is another limitation. You can
have the most beneficial trait ever, but if you die before
you can reproduce, then you cannot pass it on.
 Very long reproductive cycles
 Low number of offspring
Common Myths of Natural Selection
 Survival of the Fittest is not Survival of the Strongest
 Fittest means the ability to survive and pass on your
genes to your offspring
 You cannot create your own traits
 Acquired traits cannot be passed down
 Evolution has no grand master plan.
 There is no perfect species in science.