Download Natural Selection Intro

Natural Selection recap
Target
I can describe the process of natural selection
Definition: Natural Selection
Process by which random genetic variations are selected for by nature in a consistent, non-­random way. Both genetic
variation and
environmental
factors cause
variation
• Genetic Variation
• Heritable phenotypes
• Competition for
resources/survival
3. Competition to survive
Help me
I hope he doesn’t pick me!
Important Concept!
The variation exists BEFORE competition to survive happens
(e.g. the competing to survive does not CREATE new genetic variants, it just makes them more likely to survive and reproduce than others)
Natural Selection Acts on the
Phenotype
Example: the light colored moth could have a recessive allele for black. This genotype would not affect its fitness Fitness is how likely an organism is to reproduce and pass on their genes
Describing Selection
• Advantageous traits: selected FOR
• Traits that lower fitness: selected AGAINST
• These are driven by conditions in the environment called SELECTIVE PRESSURES
Adaptation:
inherited trait that gives a population of organisms an advantage to survival in a specific environment. Natural selection leads to adaptations becoming common
• Over many generations populations become adapted to their environment.