1. 8.3 Biological Evolution

2. Biological Evolution
Change in inherited characteristics of a population from generation to generation, which can result in new species
Evolution
History and development of something
Biological Evolution
One way process where things evolve and change

3. 1. Mutation
2. Natural Selection
3. Migration and Geographic Isolation
4. Genetic Drift

4. 1. Mutation Mutation = change in a gene
Gene  carries information from one generation to the next (made of DNA)
DNA – made of bases, ACTG
Occur as a “mess up”, then a copy of that “mess up” is made
Some helpful (ADAPTATION), some harmful
Some rapid, some slow
Changes the instructions for an organism
Mutation Examples:
Common cold – constantly mutating
Birds – beaks change from mutations, and the change helps them survive in new habitat

5. 2. Natural Selection
Traits that help an individual survive and live on to reproduce
“survival of the fittest”
4 Key factors
1. inheritance of traits from Gen1 to Gen2 with some variation
2. different environments (totally different habitats)
3. number of offspring
4. influence of environment (seasonal changes)
Example: Elephants with no tusk – didn’t get hunted – survived and flourished
People : Humans upright and larger brains?

6. 3. Migration and Geographic Isolation
1 population might split into 2, and they develop into different species
Migration = movement of organism(s) from one habitat to another
Ex: finches – some moved to different locations and gradually developed into different species that could no longer reproduce with each other
Adaptive Radiation = process when species enters a new habitat and develops into a new species
Ex: Monarch butterflies

7. 4. Genetic Drift
Bottleneck – population size gets reduced for at least one generation, then has to replenish itself with now fewer genes to choose from (decreased genetic variation)
Ex: elephant seals – poached, population decreased, had to recover, but less genetic variation
Genetic Drift = change in frequency of genes…random
Founder effect = small population gets isolated and has to start over
Ex: Amish – smaller gene pool to choose from than reset of America, often end up with strange mutations

8. Mutation Chemical changes in a DNA molecule
The change is an error, and it gets copied and passed on
Things in environment can cause this… like x-rays, radiation, chemicals
Can be good or bad for survival
Ex: Bird mutation made the beak larger and the bird ended up getting more food and living longer.

9. Natural Selection Process of increasing the # of offspring
4 main factors
Genetic variability… traits change from 1 gen to the next
Environmental variability
Different #s of offspring
Influence of environment on survival and reproduction
Takes a long time!
Characteristics of species change over time , and they change permanently to promote life
Can be seen in our lifetime\
Ex: african elephants – from 1% to 38 % had no tusks

10. Migration and geographic isolation
Migration = movement of organism(s) from one area to another
Species split into different groups, and each group develops into new species
Species tend to adapt to areas they migrate to = adaptive migration
Ex: Hawaiian birds developed different beaks depending on area

11. Genetic Drift
= changes in gene frequency and population…due to CHANCE!
Causes quick change in genetics
1. Founder Effect
Ex: pilgrims… a few people ….decreased gene pool..must repopulate
2. Bottleneck Effect
Ex: species dies out from hunters…only a few left… must reproduce…decreased gene pool