Download Natural selection

Present Knowledge
1. Fossil Record shows history of life back 3.5 Billion
Years with change over time.
2. Age of Earth 4.5 billion years old.
3. Heredity and Genetics (40 years after publication)
4. Comparative anatomy
1. Homologous –
SAME evolutionary origin/structure
DIFFERENT use/function
2. Analogous -
SAME use/function
DIFFERENT evolutionary origin/ structure
Relatively Recent Knowledge
1. Molecular Biology
-
Degree of similarity in DNA yields relationships.
Degree of difference + fossil knowledge =
estimate of rate of evolution.
2. Ontogeny
- Development of organism by the embryo
yields information about evolutionary history
of a species (phylogeny)
Forces of evolutionary change
• Natural selection
– traits that improve survival
or reproduction will accumulate
in the population
• adaptive change
• Genetic drift
– frequency of traits can change
in a population due to
chance events
• random change
Natural Selection
• Selection acts on any trait that affects
survival or reproduction
– predation selection
– physiological selection
– sexual selection
Predation Selection
• Predation selection
– act on both predator & prey
•
•
•
•
behaviors
camouflage & mimicry
speed
defenses (physical & chemical)
Physiological Selection
• Acting on body functions
–
–
–
–
disease resistance
physiology efficiency (using oxygen, food, water)
biochemical versatility
HOT STUFF!
Some fish had the
protection from injury
variation of producing
anti-freeze protein
5.5 mya
The Antarctic Ocean freezes over
Sexual Selection
• Acting on reproductive success
– attractiveness to potential mate
– fertility of gametes
– successful rearing of offspring
Survival doesn’t matter
if you don’t reproduce!
Sexual selection
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
It’s FEMALE CHOICE, baby!