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1. Evolution

1. Evolution. change over time. 1. Define a species and give examples. 2. Define a population and identify local populations. 3. Explain how extinction removes genes from the gene pool. 4. Explain the importance of the fossil record.

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1. Evolution

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  1. 1. Evolution change over time

  2. 1. Define a species and give examples. 2. Define a population and identify local populations. 3. Explain how extinction removes genes from the gene pool. 4. Explain the importance of the fossil record. 5. Explain with examples that ecology studies the varieties and interactions of living things across space while evolution studies the varieties and interactions of living things across time Prerequisites

  3. --The theory of evolution provides a scientific explanation for the history of life on Earth as depicted in the fossil record and in the similarities evident within the diversity of existing organisms. 2. Theory of Evolution

  4. Important Terms • Adaptation -- a trait that helps an organism be more suited to its environment • Theory --well-tested explanation that unifies a broad range of observations • Organism -- any living thing; bacteria, protist, fungi, animal, or plant • Evolution--change in a kind of organism over time; process by which modern organisms have descended from ancient organisms • Natural selection- process by which individual that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest • Fitness -- ability of an organism to survive and reproduce in its environment

  5. Differential survival • Differential reproduction • Chance inherited variants • Environmental conditions. 3. major concepts of natural selection

  6. A. members of a population have hereditable variations B. variation is essential to survival C. variation is random --just as likely to be harmful as helpful to organism 4. Organisms have variation

  7. A. in a population many more individuals are produced each generation than an environment can support B. causes struggle for existence 5. Organisms struggle to exist

  8. A. the most fit organisms survive and reproduce B. depends on environment and alleles available C. fitness one year may not be fitness the next --ex. In a year of drought smaller members of a species are more likely to survive because they require less resources 6. Organisms differ in fitness

  9. A. carried in the genetics B. caused by natural selection 7. Organisms become adapted

  10. Natural selection is the only evolutionary process that results in adaptations to the environment.

  11. 8. natural selection leads to organisms that are well suited for the environment (differential survival and reproduction chance inherited variants, depending on environmental conditions.)

  12. 9. Microevolution -- changes within population that may influence allele frequencies

  13. 10. Hardy-Weinberg principle -- provides a baseline by which to judge whether evolution has occurred. A. mutationB. gene flowC. random matingD. genetic driftE. selection -- Any change in allele frequencies in the gene pool of a population signifies that evolution has occurred.

  14. Hardy-Weinberg equation: p2 + 2 pq + q2 = 1 p + q = 1 p2 = frequency of homozygous dominant individuals p = frequency of dominant allele q2 = frequency of homozygous recessive individuals q = frequency of recessive allele 2 pq = frequency of heterozygous individual

  15. **Use the Hardy-Weinberg principle to solve the following problem:An investigator has determined by inspection that 16% of a human population has a recessive trait. Using this information, we can complete all the genotype and allele frequencies for the population, provided the conditions for Hardy-Weinberg equilibrium are met.

  16. 11. the relationship between environmental changes and changes in gene pools, such as genetic drift and isolation of subpopulations 1. Genetic drift -- changes in allele frequency in the gene pool due to chance -- random process -- produces different results in different populations ** there are several cypress groves in California, each one has a characteristic phenotype (all the members of a specific grove show phenotypes more similar than those of a different populations in the other groves) 2. Genetic isolation --keeps species reproductively isolated from one another

  17. 12. the role of geographic isolation in speciation. 1. Geographic isolation -- populations are separated by geographic barriers such as rivers, mountains, or bodies of water 2. Example --The Albert and Kaibab squirrels have very similar anatomical and physiological characteristics, however they vary in color. --they represent a single species that diverged into two different species due to a physical barrier = the Colorado River -- the Albert squirrels came from a population on one side of the river and the Kaibab came from a population on the other side of the river

  18. 13. genetic variation is preserved or eliminated from a population through natural selection (evolution) resulting in biodiversity 1. Allopatric speciation -- occurs after a geographic barrier prevents gene flow between populations that originally belonged to a single species. --Adaptive radiation -- Darwin’s Finches on the Galapagos Islands

  19. 2. Sympatric speciation -- occurs when members of a population achieve immediate reproductive isolation without any prior geographic barrier --polyploidy plants are reproductively isolated from diploid members of the species, but can reproduce among other polyploidy members

  20. tends to occur when a population is adapting to a changing environment • example -- antibiotic resistant bacteria have evolved because the only bacteria able to survive the antibiotics were the ones that were resistant 14. Directional selection -- extreme phenotype is favored and becomes the most common phenotype in a population

  21. A. adaptations that are best suited to a stable environment B. extreme phenotypes are selected against -- making them less common C. example -- Swiss starling birds -- when the female lays four to five eggs more young survive than when fewer than four or greater than five are laid 15. Stabilizing selection -- an intermediate phenotype is favored

  22. A. typical of organisms with a wide range for its habitat B. example -- British land snails -- some are dark in color and others are light dependent on whether they live in the grasslands or forests -- overtime it is possible that the two land snails may develop different reproductive habits 16. Disruptive selection-- two or more extreme phenotypes are favored over an intermediate phenotype

  23. -- organisms compete for food, water, space, and mates those with the best phenotypes survive and reproduce - - even after populations become adapted to their environments, variation is promoted and maintained by being diploid and heterozygous. 17. new species or variety originates through the evolutionary process of natural selection.

  24. 18. Speciation -- the splitting of one species into two or more species or one species into a new species 5. Gamete isolation -- even if the sperm and egg of different species do meet they will not fuse for a wide variety of reasons, I.e. lack of receptors on cells, female reproductive tract kills sperm of foreign species, etc 6. Zygote mortality -- If for some reason the gametes fuse the zygote rarely survives 7. Hybrid sterilization -- offspring cannot reproduce 8. Reduced fitness of F2 -- even if offspring can reproduce their offspring are weak and typically do not survive • Habitat isolation -- occupy different habitats 2. Temporal isolation -- reproduce at different times of the year 3. Behavioral isolation -- different courtship rituals 4. Mechanical isolation -- reproductive structures become physically incompatible

  25. **Research Lake Victoria in Africa.1. Look for information about Cichlids a type of fish that live there.2. How many species of Cichlids are thought to live in Lake Victoria?3. What are the possible explanations for the large number of species?4. How does this relate to evolution?

  26. 19. examples of ways in which genetic variation and environmental factors are causes of evolution and the diversity of organisms. -- Darwin’s Finches 3. Changes in the Gene Pool A. Over time the populations on each island became best adapted to local environment B. survival of the fittest -- seed sizes on the second island favor birds with longer beaks -- so the population on the second island evolves with larger beaks -- eventually the two populations become separate species 1. Founders arrive A. founder -- members from original population B. A few finches travel from South America to one of the Galapagos Islands. --where they survive and reproduce 2. Separation of Populations A. Some birds cross to a different island B. separates the gene pool

  27. **Which of the above deal with genetic variations? Explain.**Which of the above deal with environmental response? Explain**Explain how they work together in order for speciation to occur. 5. Continued Evolution A. Evolution does not stop and does not have a direction B. Species have evolved in the past and are currently evolving C. It is easier to witness evolution in species that reproduce quickly and that have many offspring 4. Ecological Competition A. birds with overlapping regions compete for the same resources B. if a bird has an adaptation that increases survival it will produce more offspring C. Over time if these bird adapt in ways that increases their differences they may become separate species

  28. 20. evolution through natural selection can result in biodiversity 4. Organisms that are best suited for their environments survive and reproduce, those that are not do not 5. Once a species becomes extinct all the genes for that species are gone 1. Biodiversity -- the sum total of the variety of organism in the biosphere 2. All of the living things on the planet, according to the theory of evolution, share a common ancestor and have evolved, and continue to evolve. 3. Natural selection is the mechanism for evolution.

  29. 21. changes at the gene level are the foundation for changes in populations and eventually the formation of new species. 1. Mutations -- changes in DNA are the raw material for different alleles 2. Alternate forms alleles allow for great diversity among members of a population 3. Without alternate forms of alleles populations would be very susceptible to extinction if conditions became unfavorable

  30. 22. natural selection acts on individuals, but it is populations that evolve--genetic mutations and genetic variety produced by sexual reproduction to diversity within a given population 1. Sexual reproduction alone cannot bring about a change in allele frequency 2. Dominant traits do not necessarily increase from one generation to the next (dominant traits are not always the most common traits in a population)

  31. 23. For a population to not evolve five factors must be met (Hardy-Weinberg Equilibrium) D. No genetic drift -- the population is very large, and changes in allele frequencies due to chance alone are insignificant E. No selection -- no selective agent favors one genotype over another --This does not occur and thus populations are constantly evolving. • no mutations -- allelic changes do no occur or changes are equal in both directions • no gene flow -- migration of alleles into or out of the population does not occur • random mating -- individuals pair by chance and not according to their genotypes and phenotypes

  32. 24. --Individuals do not evolve, yet it is the natural selection of the individuals of a population that drives evolution.

  33. A. life started simple and became more complex over time B. traces the history of life C. allows the study of particular groups D. current life forms closely resemble the most recent fossils in their line of descent 25. Fossil Evidence -- fossil record -- history of life recorded in by the remains from the past.

  34. 26. Fossil record -- traces the history of life on the big scale --can be dated using radiometric dating techniques --somewhat controversial because it is incomplete due to the nature of fossilization (need hard parts and rapid burial)

  35. Forelimbs of vertebrates are homologous -- same bones are present just in differing arrangements B. Vestigial structures -- anatomical feature that is fully developed in on group of organism, yet is reduced and has no function in another -- snakes lack hind limbs yet have a pelvic girdle to support legs which resembles the pelvic girdle of turtles and alligators --shows common ancestry 27. Anatomical Evidence-- homologous structures - structures that are closely related anatomically due to a common ancestor.

  36. 28. Homology --similar characteristics that suggest a common ancestor A. Homologous structures -- structures with similar embryological origin --suggest common ancestry --gill slits in the embryos of vertebrates B. Convergent evolution -- evolving similar structures due to similar need rather than recent ancestry C. Analogous structures -- have the same function in different organisms but have a do not share a common ancestor. -- bird wings and insect wings D. Parallel evolution -- acquisition of the same or similar character in two or more related lineages without being present in a common ancestor. -- banding of colors in moths

  37. Cacti in North America and Euphorbia in Africa both plants are succulents, spiny, and live in arid areas • Why Africa does not have cacti can be explained because cacti evolved in North America and had no way to be transmitted to Africa and vice versa C. Example

  38. 29. Molecular evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descents branched • Population -- all of the members of a single species that occupy a particular area at the same time • Species -- members interbreed and have a shared a shared gene pool that is unique to the specific members

  39. species are reproductively distinct groups of organisms that can be classified based on morphological, behavioral, and molecular similarities

  40. 30. Molecular data C. Protein comparisons -- more similar organisms have fewer differences in the number of amino acid sequences for specific proteins --cytochrome C -- 3 differences between chickens and ducks --13 differences between humans and chickens A. speciation occurs when mutations bring about changes in the base pair sequences of DNA B. more closely related species share more similar sequences of proteins

  41. 31. DNA and RNA comparisons 3. Nucleotide sequences of particular genes -- provides numeric data that is missing from DNA hybridization 4. Mitochondrial DNA -- changes rapidly, often used to compare the relatedness of two species instead of nuclear DNA 1. rRNA has changed very little over time so it is used commonly as a way to compare the relatedness of two species --gave rise to the three domain system 2. DNA hybridization -- a single strand from each species are combined and the better the two strands stick together the closer the two species are related --red pandas versus giant pandas

  42. 32. Molecular Clocks -- indicate relatedness and evolutionary time because neutral changes in nuclei acids occur at a constant rate allowing for a time frame to be established**Best data comes from a combination of all of the above techniques.

  43. -- Phylogeny -- discovers the evolutionary relationships between species • The degree of kinship between organisms or species can be estimated from the similarity of their DNA and protein sequences

  44. 33. Interpret a cladogram or phylogenic tree showing evolutionary relationships among organisms. B5.r2d B. phylogenic tree -- a diagram that indicates common ancestors and lines of descent. A. cladogram -- diagram that traces the evolutionary history of the group being studied based on derived (special) characters

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