Evolution

4 main ideas of evolution

Variation in Populations

Inherited Traits

Offspring Compete

Survival of the Fittest

Mutations

Germ-line mutations occur in gametes and can be passed down To offspring. THESE ARE THE MOST IMPORTANT IN EVOLUTION!

Somatic-cell mutations occur in all other cells found throughout the organism and CAN NOT be passed down to offspring.

Natural selection

Directional

Stabilizing

Disruptive

The genetic Drift

Bottleneck effect- occurs when a population’s size declines dramatically because of some dramatic event (earthquake, epidemic, etc). It is a random event where some genes disappear from the population and the survivors have a smaller gene pool.

Founder effect- when a small number of individuals establishes a new population and a loss of genetic variation ensues. This can lead to a new species.

Barriers

Pre-zygotic Barriers
Barriers that prevent mating from occurring in the first place Temporal, ecological (physical barriers), behavioral, Mechanical (incompatible sexual structures)

Post-Zygotic Barriers

Implies that pre-zygotic barriers did not prevent fertilization

Three types:

five fingers

Small population(pinky)

Nonrandom mating (ring finger)

Mutations (middle finger)-

Gene flow from emigration/immigration ( pointer finger)-

Adaptationsm (thumb)

Evidence of evolution

  1. Fossil Record
  1. Anatomy and morphology
  1. Embryology
  1. Molecular Traits/Biochemistry
  1. Biogeography

Structures

• Homologous structures- similar in their structure but perform Different functions

• Analogous structures- different morphology yet perform the same Function

• Vestigial structure- structure is still present, yet is not functional

Macroevolution
scale that transcends the boundaries of a single species

microevolution
happens on a small scale (within a single population)