Evolution and Biodiversity G. Tyler Miller’s Living in the Environment 14 th Edition Chapter 5 Part 1 G. Tyler Miller’s Living in the Environment 14 th Edition Chapter 5 Part 1

Chapter 5: Essential Questions / Objectives Briefly describe the evolution of life from chemical evolution to the development of eukaryotic cells. Briefly describe the evolution of life from chemical evolution to the development of eukaryotic cells. Briefly describe the theory of evolution, being sure to include the roles played by variation within the gene pool and natural selectionBriefly describe the theory of evolution, being sure to include the roles played by variation within the gene pool and natural selection. Briefly describe the theory of evolution, being sure to include the roles played by variation within the gene pool and natural selection Define natural selection and the three conditions that are necessary for evolution of a population by natural selection. Define natural selection and the three conditions that are necessary for evolution of a population by natural selection. Summarize and address two common misconceptions about evolution. Summarize and address two common misconceptions about evolution. Define coevolution. Define coevolution.

Describe the tools available to researchers for learning the evolutionary history of life. (evidence for evolution) Distinguish between a specialist and a generalist. Evaluate the conditions that favor these two approaches. Define ecological niche. Distinguish between condition and resource; fundamental niche and realized niche. List the factors that determine the realized niche. Define speciation and compare allopatric speciation with sympatric speciation. Indicate which of these mechanisms is more common. Briefly describe, extinction, speciation, and adaptive radiation.

Define extinction and distinguish between background extinction and mass extinction. Discuss the role of humans on the rate of extinction at present. Discuss the pros and cons of artificial selection and genetic engineering. Consider the possible environmental impacts on resource use, pollution, and environmental degradation. Indicate what it is that has allowed humans to have such a profound influence

Origins and Early Evolution of Life Chemical evolution Chemical evolution of organic molecules, biopolymers, and systems of chemical reactions were needed to form the first cell. It took about 1 billion years. Chemical evolution Biological evolution Biological evolution followed, from single-celled prokaryotic bacteria to single-celled eukaryotic organisms to multicellular organisms. Is has been continuing for 3.7 billion years. Biological evolution Knowledge of past life comes from fossils, ice-core drilling, chemical analysis, and DNA analysis. These records are incomplete

The Five Parts of Darwin’s Theory of Evolution Perpetual Change Common Descent Multiplication of Species Gradualism Natural Selection The Theory of Evolution - Widely accepted scientific idea that all life forms developed from earlier life forms. Although this theory conflicts with the creation stories of many religions, it is the way biologists explain how life has changed over the past billion years and why it is so diverse today. Galapagos Islands satellite view.

Darwin’s Observations and Inferences: Darwin’s Observations and Inferences: Observation 1 – Organism have great potential fertility Observation 2 – Natural populations normally remain constant in size except for minor fluctuations Observation 3 – Natural resources are limited Inference 1 – There exists a continuing struggle for existence among members of a population Observation 4 – All organisms show variation Observation 5 – Some variation is heritable Inference 2 – There is differential survival and reproduction among varying organisms in a population

What Drives Evolution ? Variation Meiotic mix Population Dynamics Mutations Struggle for Existence CompetitionPredation Selective advantage Role of mutation

Natural Selection Process by which a particular beneficial gene (or set of genes) is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions. Conditions for Natural Selection Included: 1.There is genetic variation within the population 2.Traits must heritable – past from one generation to the next 3.The adaptation allows the organism to better survive under prevailing environmental conditions. Differential reproduction Differential reproduction - Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits. Differential reproduction

Differential Reproduction Misconceptions about Evolution Evolution is the change in a population's genetic makeup over time. Therefore, population evolve not individuals Evolution is concerned with leaving the most descendants, NOT the strongest ones. There is no master plan to achieve genetic perfection.

Evolution and Adaptation Microevolution: small genetic changes that occur in a population. “variation within a species” Genes mutate Individuals are selected Populations evolve Microevolution: small genetic changes that occur in a population. “variation within a species” Genes mutate Individuals are selected Populations evolve Macroevolution: long term, large scale evolutionary changes through which new species form from ancestral species and other species are lost through extinction. “speciation” Gene pool: a collection of genes potentially available to members’ offspring in the next generation “ genetic variability in a population” Sexual reproduction leads to random recombination of alleles from individual to individual. Coevolution: Interacting species can engage in a back-and-forth genetic contest in which each gains a temporary genetic advantage over the other. Gene pool: a collection of genes potentially available to members’ offspring in the next generation “ genetic variability in a population” Sexual reproduction leads to random recombination of alleles from individual to individual. Coevolution: Interacting species can engage in a back-and-forth genetic contest in which each gains a temporary genetic advantage over the other. Evolutionary Arms Race

Mutation: random changes structure or number of DNA molecules in a cell that can be inherited by offspring. Mutations occur in two ways: Gene DNA is exposed to external agents like X rays, chemicals (mutagens), or radioactivity Random mistakes that occur in coded genetic instructions Only mutations in reproductive cells are passed to offspring. Many mutations are neutral; some are deadly; and a few are beneficial. Fruit fly (Drosophila melangoaster) Vestigial Wing. Fruit fly (Drosophila) adult, dorsal view

Types Selection Directional Directional – demonstrated by the peppered moths StabilizingStabilizing – tends to favor the average Disruptive Disruptive – may lead to speciation Stabilizing Disruptive

What Limits Adaptation? A population's gene pool and its rate of reproduction limit the population's ability to adapt to new environmental conditions. The only genetic traits that can adapt are those already in the gene pool. A population's reproductive capacity limits those genes that can adapt. Genetically diverse species that reproduce quickly can often adapt quickly. Populations that reproduce slowly take a long time to adapt through natural selection. For a new favorable trait to predominate, most of an existing population would have to die prematurely.