Evolution: change in the genetic makeup of a population over time.
The concept of evolution had its beginnings about 700-650 B.C. in Greece (although it appears in some forms previous to that date in Egyptian, Chinese, Hindu, and Assyria writings).
Macroevolution: changes in the kinds of animals and plants on earth that take place over long periods of time; new forms replace old ones. evolutionary change on a grand scale.
Microevolution: progressive change in gene frequencies. natural selection allows some individuals to produce more offspring, therefore a population contains more individuals with those genetic characteristics (peppered moths)
Adaptation: inherited trait (anatomical structure, physiological process, or behavioral trait) that improves an organism's chance of survival and reproduction in a particular environment.
History of Evolutionary Thought
Thales of Miletus (640-546 B.C.) first proposed the idea of evolution defined as the development of the more complex forms from the simpler forms.
Aristotle believed that nature fashioned organs in the order of their necessity; that nature is a result of intelligent design and direction, evolved from a primordial mass created by an intelligent force. He stated that evolution proceeded according to a set of rules.
Georges Louis de Buffon (1707-1788): French natural philosopher who wrote a book containing the points later proposed by Darwin. (tendency of living things to outstrip their food supply; variations with species; similarity of structure among living forms; need for long periods of time for evolution.)
James Hutton (1726-1797): a geologist who proposed that natural forces currently at work in the earth are sufficient to account for the geologic phenomena in the earth today (uniformitarianism). stated that indefinite amounts of time were needed to achieve today's results.
Erasmus Darwin (1731-1802): (Charles' grandfather) proposed that competition and selection were means of evolutionary change; overpopulation enhanced competition.
Jean Baptiste de Lamarck (1744-1829): forwarded the idea of evolution by acquired characteristics which could be passed on to offspring.
Charles Lyell (1797-1875): geologist who forwarded Hutton's ideas about time and natural forces at work on the earth.
Charles Darwin (1809-1882): wrote Origin of Species, explaining natural selection using evidence from his voyages in South America.
Alfred Wallace: developed theory of evolution by means of natural selection at the same time as C. Darwin.
Evidence for Evolution by Natural Selection
Fossil Record
Comparative Anatomy
Homologous Structures
Analogous Structures
Vestigial Structures
Comparative Embryology
Comparative Behavior
Comparative Biochemistry
Biogeography
convergent evolution: evolution of same adaptations in unrelated organisms
adaptive radiation: descendants of an ancestral group spread (radiate) to other areas.
Causes of Evolution
Mutation
Mating preference
Genetic Drift
founder effect: change in allele frequencies when new population arises from one or a few individuals.
population bottleneck: number of individuals falls.
Gene flow
Natural selection: main mechanism of evolution. process by which populations change in response to their environment as individuals with better adaptations leave more offspring. due to a differential reproduction of genotypes. individuals with some genotypes produce more offspring than those with other genetic combinations.
stabilizing selection
directional selection
disruptive selection