Chapter 13 The Theory of Evolution - the change of something overtime. Theory- scientific truth based upon data or evidence.
Jean Baptist de Lamarck ….. Theory of Acquired Traits – –features increased in size because of use or reduced in size because of disuse! –these acquired traits are passed to offspring –change in species is due to the physical conditions of life ( environment)
Charles Darwin… –A Naturalist who, in 1831, traveled on the “HMS Beagle” for a five year expedition to collect, study, and store biological specimens discovered. Father of the Theory of Evolution
Alfred Russel Wallace…. Studied the birds of Malaysia and hypothesized the same Theory of Natural Selection as Darwin…. Darwin then published his earlier works…
Darwin’s Pigeons Artificial Selection - By breeding pigeons that had a desirable trait, the offspring would carry these same traits. Natural Selection - Nature selects or chooses which traits in an organism will be passed on to future generations.
Darwin’s Theory of………………. Natural Selection 1. Variations exist within populations 2. Some variations are more advantageous than others 3. Organisms produce more offspring than can survive 4. The “fittest” survive and reproduce! Thus the species modifies itself over time. (Natural Selects who lives)
The Galapagos Islands Darwin observed islands with great biodiversity. Organisms were best suited for their own particular climate. Island organisms seemed to have adapted to each particular island climate. After 22 years of data analysis he formed his Theory of Adaptation by Natural Selection.
Darwin’s Theory (2 Parts) Descent with modifications- species of today came from ancestors of the past but with changes that have allowed them to survive to the natural surroundings that they live it. Modification by natural selection- Changes within a species is driven by the natural surroundings and traits best suited for survival within it. Traits not well suited will be lost.
Adaptation Types Populations adapt as the environment changes –1) Mimicry…..A structural adaptation that provides protection by enabling it to copy another species. (Monarch and Viceroy) –.
2) Camouflage….. A structural adaptation that enables the organism to blend in with its environment. ( Peppered Moths)
3) Physiological Adaptations…………. Bacteria that have developed a resistance to antibiotics…….. Tuberculosis resistant strains
Biological Molecules…… Proteins Sequences– few changes in amino acid sequences share common ancestors. DNA Sequences – Similar gene sequences show evolutionary ancestors.
Points of Evidence for Evolution 1. Fossil Record – Past History 2.Anatomical Studies – –similar body parts A) Homologous structures - Modified structures seen among different groups of descendents. B) Analogous structure - Body part similar in function but different in structure ( Wings of bird and butterfly)
3. Vestigial Organs - Structures that have no function in the organism today but may have been used. Ex. Appendix 4. Embryological development - Organisms that develop similarly as embryos have an evolutionary relationship. (vertebrate embryos- have tails and gill slits )
Mechanisms of Evolution or Natural Selection Reproductive Isolation- Occurs when a population is separated by geographic, mating, or reproductive changes. Can no longer breed successfully.
Speciation The formation of a new species from an ancestral form. Occurs when inter-breeding or the production of fertile offspring is prevented first forming subspecies…. Divergent Evolution - An ancestral species evolves into many different species ( Adaptive Radiation) Convergent Evolution -Distantly related organisms evolve similar traits. Ex. whales and fish
Speciation can occur quickly or slowly. Gradualism- Species originate through a gradual accumulation of adaptations. Punctuated Equilibrium - Occurs in rapid bursts with long periods of stability in between.
Changes in Genetic Equilibrium Genetic equilibrium - Allele frequencies do not change over time (non evolving) 3 Ways Evolution Occurs..... 1) Mutations - Cause genetic changes in gene pool 2) Genetic Drift - Changes due to chance events (Small populations) 3) Gene flow - Movement of genes into or out of a population