EVOLUTION
Darwin s Theory of Evolution n Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. n A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.
Voyage of Beagle n Dates: February 12th, 1831 n Captain: Charles Darwin n Ship: H.M.S. Beagle n Destination: Voyage around the world. n Findings: evidence to propose a revolutionary hypothesis about how life changes over time
Living Organisms and Fossils n Darwin made observations and collected the preserved remains of ancient organisms, called fossils.
The Galapagos Island n The smallest, lowest islands were hot, dry, and nearly barren-hood Island-sparse vegetation n The higher islands had greater rainfall and a different assortment of plants and animals
Animals
Darwin s Finches
1. Overproduction Each species produces more offspring than can survive
2. Variation n Each individual has a unique combination of inherited traits. t Adaptation: an inherited trait that increases an organism s chances of survival
Why is Variation Important? Because the environment changes. The more variation within a species, the more likely it will survive EX: If everyone is the same, they are all vulnerable to the same environmental changes or diseases The more variation of types of species in an habitat, the more likely at least some will survive EX: Dinosaurs replaced by mammals
3. Competition n Individuals COMPETE for limited resources: u Food, water, space, mates n Natural selection occurs through Survival of the fittest t Fitness: the ability to survive and reproduce n Not all individuals survive to adulthood
4. Selection n The individuals with the best traits / adaptations will survive and have the opportunity to pass on it s traits to offspring. u Natural selection acts on the phenotype (physical appearance), not the genotype (genetic makeup)
Individuals with traits that are not well suited to their environment either die or leave few offspring. Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.
Lamarck
Lamarck s Theory of Evolution n Tendency toward Perfection(Giraffe necks) n Use and Disuse (bird s using forearms) n Inheritance of Acquired Traits n Are you still paying Attention?
Publication of Orgin of Species n Darwin published his research in 1859 n The Origin of Species
Natural Selection & Artificial Selection n Natural variation--differences among individuals of a species n Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.
Evolution by Natural Selection n The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities n Survival of the Fittest-Some individuals better suited for the environment
Natural Selection n Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment
Descent n Descent with Modification-Each living organism has descended, with changes from other species over time n Common Descent- were derived from common ancestors
Evidence for Evolution n The Fossil Record- Layers show change
Evidence of Evolution n Geographic Distribution of Living Things-similar environments have similar types of organisms
Homologous Structures n Homologous Structures-structures that have different mature forms in different organisms, but develop from the same embryonic tissue
Evidence for Evolution n Vestigial organs-organs that serve no useful function in an organism n i.e.) appendix, miniature legs, arms
Vestigial Organs u Vestigial Organs: leftover traces of evolution that serve no purpose
Similarities in Early Development
Biochemical Evidence Biochemistry: DNA with more similar sequences suggest species are more closely related EX: Humans and chimpanzees share more than 98% of identical DNA sequences