Charles Darwin
No one can think about evolution and natural selection without thinking of Charles Darwin. Darwin quit medical school and went to Cambridge University to become a clergyman. After graduating, Darwin took a job aboard the HMS Beagle for a voyage around the world. Darwin was fascinated by the different organisms he encountered during his time on the HMS Beagle, especially while docked in the Galapagos Islands. Darwin's observations and hypothesis were recorded in his journal and inspired his life long study of his theory of natural selection and evolution.
Darwin's Observations•More offspring are born than can survive
•Natural resources are limited •Individuals of a population vary in their characteristics and those traits are passed on to their offspring •“Survival of the Fittest” |
What is fitness?
An organism's fitness describe the ability for an organism to survive and reproduce. Organism who live longer and reproduce large amounts of offspring are more fit than an organism that dies without reproducing. Some organisms will be more fit because they possess a unique adaptation. Adaptations are features or characteristics an individual possesses that allow them to be more successful in their environment.
Natural Selection is when populations evolve to possess the traits of individuals with the highest fitness.
Natural Selection is when populations evolve to possess the traits of individuals with the highest fitness.
Microevolution
Microevolution is when the gene pool of a population changes over time. Populations evolve NOT INDIVIDUALS!
Five Causes of Microevolution:
Genetic DriftChanges to the populations gene pool frequency because the original population is drastically reduced.
Examples: Founders Effect and Bottleneck Effect MutationAny change in an organism's DNA to create a new allele, or version of a gene.
Natural Selection |
Gene FlowAlleles, or variations of specific genes, are gained or lost from a population by movement of individuals or gametes.
Examples: Migration and Immigration Non-random MatingProducing and raising offspring requires a significant amount of energy. Females, or the individual responsible for rearing offspring, carefully select mates with specific traits to ensure her offspring will contain genes to increase offspring survival.
Male giraffes battle with one another to win reproduction rights with a female using their necks as weapons. Males with larger and stronger necks will be able to mate with the female and pass on their successful genes to their offspring.
Other example...
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