What is a Theory?
An educated guess? No… Much more… A theory is based on extensive evidence. A scientific theory provides a basis for explaining observations of the natural world and for making testable predictions.
New Definitions:
Natural Selection – the way in which nature favours the reproductive success of some individuals within a population over others
Inference – a conclusion based on evidence presented
Coherent – logical, consistent
Mutation – a change in the genetic code of an allele, the change may have a positive effect (Beneficial), a negative effect (Harmful), or no effect (Neutral).
Introduction to Evolution
The theory of evolution is a scientific theory based on a large body of evidence that can be used to explain the history of life on Earth. It allows scientists to make accurate and useful predictions. Evidence includes: the fossils of ancient life forms, genetic analysis, comparative anatomy, and distribution of living things on Earth.
The Changing World
On earth there are millions of species and trillions of individual organisms that grow and mature. New generations begin and disappear. The physical earth also changes. Scientists have concluded that entire species change over time (ie: snowshoe hares in the arctic).
Why do we study Evolution?
To understand how we came to be; to predict what might happen in the future; and for medical advances.
For example, Bellamy’s Frogs: Poisonous Frogs = Medical advances
We use a variety of drugs to kill bacteria and parasitic organisms. Poison produced by living organisms can be studied and isolated to be used in antibiotics. The frogs (and other species) have EVOLVED to produce these poisons to ward off predators. Evolutionary biology is a vital tool for maintaining and enhancing our own health as well as that of the diversity of life on earth.
How does Evolution happen?
Mutations
· Mutations can be Neutral, Harmful, or Beneficial (ie: think of them like typos in the genetic code… they happen very often)
· Neutral – while there is a change in the DNA, it has no immediate effect on the individual. Most common mutation.
· Harmful – can affect the reproductive success of an individual.
· Beneficial – can give an organism a better chance at survival in their environment, and enhances their chances of reproductive success. Least common mutation.