Charles Darwin
Natural Selection
is a mechanism that explains how changes in population occur when organisms with favorable variations or traits for a particular environment survive, reproduce and pass on those variations to the next generation.
Artificial Selection (Selective Breeding)
is when a breeder crosses two organisms in the hope of expressing a desirable trait.
Darwin's proposed explanation of natural selection.
1. In nature, organisms produce more offspring than will survive.
2. In any population, there is always variations among species
3. Individuals with favorable variations or traits survive the environment, passing on those variations or traits to the next generation
4. Overtime, offspring with certain variations make up most of the population and may look entirely different from their ancestors.
What are the mechanisms that drive evolution?
- The mechanisms that drive evolution are mutations and genetic recombination through sexual reproduction. These mechanisms are responsible for creating variations in populations.
Problem:
Use Darwin's theory of natural selection to explain why some bacteria that was once susceptible to certain antibiotics are becoming resistant. In this instance, what is the favorable trait?
Answer:
- In any given population of bacteria there is variation. Some variations are favorable, like resistance to antibiotics.
- Bacteria with favorable traits, like resistance to antibiotics survive, reproduce and pass on the traits.
- Overtime, resistant bacteria make make up most of the population because they are the ones that survived, reproduced and passed on the traits.
How can over-crowdedness lead to natural selection?
- Over-crowdedness leads to competition. During competition, organisms that have favorable traits survive, reproduce and pass on those traits.
What are traits?
- Traits are your characteristics.
- Ex, skin color, eye color and height.
Adaptive traits
are any structural or physiological or behavioral characteristics that help the organism survive the environment.
Camouflage (Structural adaptation)
is when the organism blends in with the environment. This trait helps the organism survive by allowing the organism to escape predators or become less visible to its preys.
Mimicry (Structural adaptation)
To copy the appearance of an organism.
Physiological Adaptation
are changes in an organism metabolic processes that enable the organism to survive its environment. For example, bacteria's resistance to penicillin is a type of physiological adaptation.
ANIMAL ADAPTATION INTERACTIVE
Natural Selection Interactive
Natural Selection Interactive 2
Natural Selection Interactive 3
