During the 1820's notions of evolution were becoming feared in England. As a boy Darwin had a keen intrest in nature. Darwin began to develop his views on what he called natural selection. This concept was borrowed from animal breeders who choose or select as breeding stock thos animals that possess certain traits they want to emphasize in offspring. Darwin applied his knowledge of domesticated species to naturally occurring ones, and he recognized that in undomesticated organisms, the selective agent was nature but not humans.
Ex: All domestic breeds share a common ancestor the wolf. Humans allow only certain dogs to. Reed to breed to emphasize specific characteristics.
By late 1830's Darwin had realized that biological variation within a species was crucial.
By 1840 Darwin had written a summary of his views on natural selection but he didn't have enough info to support his hypothesis.
Natural Selection
- In Darwin's early research he realized that natural selection was the key to evolution.
- All species are capable of producing offspring at a faster rate than food supplies.
- A biological variation within all species.
- In each generation more offspring produced then can actually survive.
- Individuals who possess favorable variations or traits have an advantage on people who can't .
- The environmental context determines whether or not a trait is beneficial. Favorable is that
- one setting may be liability in another. Therefore the traits that become most advantageous are the results of natural process.
- Traits are inherited and passed onto the next generation. Individuals who produce more offspring in comparison to others are said to have greater reproductive success.
Darwin's natural selection operates on individuals, either favorably or un favorably but it's the population that evolves.
Example:
Natural selection acts to preserve and accumulate minor advantageous genetic mutations. Suppose a member of a species developed a functional advantage it grew wings and learned to fly. Its offspring would inherit that advantage and pass it on to their offspring. The inferior disadvantaged members of the same species would gradually die out, leaving only the superior advantaged members of the species.
Example:
Natural selection acts to preserve and accumulate minor advantageous genetic mutations. Suppose a member of a species developed a functional advantage it grew wings and learned to fly. Its offspring would inherit that advantage and pass it on to their offspring. The inferior disadvantaged members of the same species would gradually die out, leaving only the superior advantaged members of the species.
