Evolution
Slight changes in the inherited
characteristic of a species
through adaptations over time
Charles Darwin
Father of Evolution by Natural
Selection
Natural Selection
Selection by the environment of
organisms better adapted to
survive and reproduce
Fitness
Physical traits and behaviors that
enable organisms to survive and
reproduce in their environment
Adaptations
Inherited changes that allow
organisms to be better suited to
survive and reproduce in a
particular environment
Survival of the Fittest
The fittest (best adapted)
organisms within a particular
environment will out-compete
those who aren’t as fit
Competition (Struggle
for Existence)
Individuals within a species will
struggle to survive and have to
compete for limited resources in
their environment
Over Production of
Offpspring
More offspring are produced
than can survive
Differential Survival
and Reproduction
Organisms with traits favored by
the environment will have a higher
chance of surviving and
reproducing and therefore passing
on their traits
Genetic Variation
Differences in inherited
characteristics of species that get
passed on to the next generation
Things that lead to
Genetic Variation
Mutations, Sexual Reproduction,
and Gene Flow from different
populations
4 Processes of
Evolution by Natural
Selection
1. Competition (Struggle for Existence)
2. Overproduction of offspring
3. Differential Survival and
Reproduction
4. Genetic Variation
Artificial Selection
Process by which humans breed
other animals and plants for
particular desirable traits. AKA
Selective Breeding
5 Evidences of
Evolution
Fossils
1. Fossils
2. Embryos
3. DNA
4. Anatomy
5. Biogeography
Any trace or remains of an
organism that has been
preserved by natural processes
Geographical
Distribution
The location of a particular
organism around the world
Embryo
Organism in the earliest stages
of development
Embryological
Similarities
Comparison of the similarities
between the embryological
developments of different species
Genomics
A branch of Biology that
sequences and analyzes DNA to
determine the function and
structure of genomes
Genome
The complete set of DNA within
a single cell of an organism
Biochemical
Similarities
How alike the structure of the
DNA and protein molecules are
between species
Gradualism
New species evolving from
existing species though changes
that add up over long periods of
time
Cladogram
A branching diagram showing
evolutionary relationships
between species
Derived Characteristics
A sudden change in the structure
or amount of genetic material
Structural Similarities
Similarities in physical features
between species
Homologous Structures
Similar structurally but each has
a different function
Analogous Structures
Structures with similar functions
but have different internal
structures
Vestigial Structures
Remnants of structures that were
functional in ancestors but now are
reduced in size and serve little to
no function
Biogeography
Equilibrium
Species living geographically closer show
more similarities, despite differences in
environment, than two species living in the
same type of environment but
geographically far away
A state of balance, no change
Gene Pool
All the different variations of
genes in an interbreeding
population
Genetic Equilibrium
A condition where a gene pool is
not changing because the
evolutionary forces acting on the
alleles are equal
5 Conditions for
Equilibrium
1. Large breeding population 2.
Random Mating 3. No Mutations 4.
No Migration 5. No Natural
Selection
Genetic Drift
Chance events that change the
genetic composition of a
population.
Founder Effect
The loss of genetic variation when
a new colony is formed by a small
number of individuals from a
larger population
Bottleneck Effect
Three Types of
Selection
The dramatic loss of genetic
variation due to environmental
effects or human activities
1. Stabilizing Selection
2. Directional Selection
3. Disruptive Selection
Stabilizing Selection
The extreme traits in a population
are selected against and the
average traits are favored
Directional Selection
One extreme trait is selected for,
resulting in the population shifting
towards the other extreme
Disruptive Selection
The extreme traits are both
selected for resulting in a reduction
of individuals with the
intermediate traits
Stabilizing Selection
Graph
Directional Selection
Graph
Disruptive Selection
Graph