Chapter 13 The Theory of Evolution Section 1: The Theory of Evolution by Natural Selection Section 2: Evidence of Evolution Section 3: Examples of Evolution

Section 1 The Theory of Evolution by Natural Selection Objectives: Identify several observations that led Darwin to conclude that species evolve. Relate the process of natural selection to its outcome. Summarize the main points of Darwin's theory of evolution by natural selection as it is stated today. Contrast the gradualism and punctuated equilibrium models of evolution.

Darwin Proposed a Mechanism for Evolution Science Before Darwin’s Voyage In 1809, Jean Baptiste Lamarck Frenchman, studied medicine and Botany, Wrote many books about biology In 1801 he suggested Evolution occurs due to use/disuse of features. Acquired traits are passed on the future generations Thought evolution was linked to environmental conditions

Section 1 The Theory of Evolution by Natural Selection Darwin Proposed a Mechanism for Evolution Charles Darwin Born in England, 1809 Age 16: Went to Medical School in Scotland (skipped class to collect specimens) 1827, sent to England to become a minister, received a degree in theology 1831, Age 22 he went as an unofficial naturalist on HMS Beagle 1836 finished survey of South American coast on HMS Beagle Published Origin of Species in 1859 Died in 1882

Darwin Proposed a Mechanism for Evolution Darwin’s Observations concluded that animals on the coast of South America that resembled those on the nearby islands evolved differences or descended with modification after separating from a common ancestor.

Section 1 The Theory of Evolution by Natural Selection Darwin Proposed a Mechanism for Evolution continued Growth of Populations Darwin was influenced by Thomas Malthus, who wrote that populations tend to grow as much as the environment allows. Thomas Malthus, English economist

Section 1 The Theory of Evolution by Natural Selection Darwin’s Theory proposed that natural selection favors individuals that are best able to survive and reproduce and this causes populations to evolve. Natural Selection Natural selection is differential reproductive success and natural selection leads to adaptations in a population.

Section 1 The Theory of Evolution by Natural Selection Darwin’s Ideas Updated Change Within Populations Natural selection causes the frequency of certain alleles in a population to change over time. Certain forms of the traits become more common because more individuals carry them. Mutations and sexual reproduction increases variations

Darwin’s Theory Updated Species Formation Under certain conditions, change within a species due to reproductive isolation can lead to new species. Both squirrels have developed different characteristics over time

Section 2 Evidence of Evolution Objectives: Describe how the fossil record supports evolution. Summarize how biological molecules such as proteins and DNA are used as evidence of evolution. Infer how comparing the anatomy and development of living species provides evidence of evolution.

Section 2 Evidence of Evolution The Fossil Record Formation of Fossils Evidence of orderly change can be seen when fossils are arranged according to their age.

Section 2 Evidence of Evolution Anatomy and Development Vestigial Structures Reduced or nonfunctional vestigial structures, such as hind limbs in whales, provide evidence of an organism’s evolutionary history.

Homologous Structures :structures in different organism that indicate a shared ancestry, include the vertebrate forelimb. Analogous structures: Structures of different organisms that have the same function but not related by ancestry.

Darwin’s Theory Updated The Tempo of Evolution Gradualism is a process of evolution in which speciation occurs gradually, and punctuated equilibrium is a process in which speciation occurs rapidly between periods of little or no change.

Section 2 Evidence of Evolution Biological Molecules Proteins Differences in amino acid sequences are greater between species that are more distantly related than between species that are more closely related. Nucleic Acids Differences in DNA sequences are greater between species that are more distantly related than between species that are more closely related.

Section 3 Examples of Evolution Objectives: Identify four elements in the process of natural selection. Describe how natural selection has affected the bacteria that cause tuberculosis. Relate natural selection to the beak size of finches. Summarize the process of species formation.

Section 3 Examples of Evolution Natural Selection at Work Factors in Natural Selection Individuals that have traits that enable them to survive in a given environment can reproduce and pass those traits to their offspring.

Evolution in Darwin’s Finches Experiments show that evolution through natural selection has occurred in beak size in Darwin’s Finches.

Evolution of Antibiotic Resistance Experiments show that evolution through natural selection has occurred within populations of antibiotic-resistant bacteria, such as the bacteria that cause tuberculosis, MRSA (Methicillin resistant Staphylococcus Aureus)

Section 3 Examples of Evolution Formation of New Species Speciation : begins as a population adapts to its environment. Forming Subspecies :Populations of the same species that differ genetically because of adaptations to different living conditions are called subspecies. Newly formed subspecies are on the road towards speciation. Maintaining New Species: Reproductive isolation through reproductive barriers keeps species from breeding with one another.