Biology II. Evolution

Transcription

1 Biology II Evolution

2 Observation-Something we know to be true based on one or more of our five senses. Inference- A conclusion which is based on observations Hypothesis- a testable inference usually stated in the if then format. Fact- Something that can be verified with the use of a tool like weight, length, or temperature Scientific Law- relationship that is limited in scope and can often be described by a mathematical formula

3 Scientific theory- an idea that scientists are sure of, it is broad in nature and can be used to make predictions for experimental results. A theory must withstand challenges (hundreds of thousands or more) to be widely accepted. Examples include: Atomic theory, Cell theory, Plate tectonics, Evolution This usage of the word is very different than the everyday usage of the word and can be a confusing concept for people who do not understand this. The common usage of the word, is more related to the scientific definition of a hypothesis.

4 Remember good science is ALWAYS: 1. Testable 2. Repeatable 3. Falsifiable 4. Published to invite challenge Science is better today than it has ever been because technology has greater capability than ever and communication is better resulting in greater scrutiny. (Think of how long it would take information to travel in 1800s vs. today?)

5 Religion- based on faith and depends on a source of truth. Religion is rarely if ever testable or falsifiable. Evolution-The idea that organisms change through time, that one species can develop into a new and different species, and that all of the species present today are descendants of other previous species

6 Darwin drew many of his ideas from other scientist including: Linnaeus, Hutton, Lyell, Malthus. Carolus Linnaeus grouped similar species into increasing general categories from species, genus, family, order, class, phylum & kingdom. James Hutton- a geologist proposed that earths geologic features could be explained by gradual mechanisms still operating today. Lyell based on the work of Hutton, proposed the principle of Uniformitarianism- Idea that the Earth s geological processes which are at work today are the same ones that have always been at work. This establishes an incredible lifespan for Earth. 4.7 billion years.

7 Bell Ringer (5-10 minutes) In your notebook in paragraph form: Please describe the difference between the common (incorrect) usage of the word Theory versus the scientific usage of the word. Map out the contributions of 1)Linnaeus 2)Hutton/Lyell 3)Malthus (hint: its in your reading)

8 Darwin Reading: Bill Bryson

9 Fossils Layers of deposited sediment Younger stratum with more recent fossils Older stratum with older fossils

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15 What do you know about evolution? (Take a few moments to write down in your notebook) Reproductive Success of the Fitest

16 Darwin s idea is simple. Thomas Malthus showed that populations have the ability to out grow their food supplies. Yet this does not happen, so Darwin assumed that environmental factors must prevent unlimited population growth and these factors were in some way selective and not random, leading populations of species to change or be modified from one generation to the next. Individuals that are most suited to survive the environmental pressures pass their genes on more efficiently. The increase in genes that are favored by the environment is known as adapting

17 Fitness is a term used to identify organisms that are well adapted. (survive to reproduce) Adaptive advantage- a trait that gives an individual a more favorable chance of surviving and breeding Morphology: Homologous Structures are structures that are present in more than one species as a result of descent from a common ancestor Analogous structures are structures that are similar in two or more species but have developed from different species.

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19 Get out the Bill Bryson reading and review the contents.

20 Adaptive Advantage activity with & w/o thumbs

21 Vestigial organs are features that still exist in species today but no longer serve any purpose Conserved genes are genes that are still present in an organism but no longer get turned on, occasionally however these genes do get expressed resulting in the expression of a gene, which was present in an ancestor species. Embryology- All animals start out as a single cell and develop from there into their multi-cellular form. The longer that two organisms look alike within the womb, the more closely related they probably are. Similarities in macromolecules- All organisms use proteins and the more similar proteins are between two organisms, the more closely related they are.

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26 Bell Ringer Respond for first five minutes of class (in your notebook) 1.Why do humans have tail bones? 2.Knowing that whales and horses are both mammals, explain the differences and similarities of the horses front legs with the whales pectoral fins.

27 Coevolution- When two organisms live in such close association that as one organism changes, so does the other. Convergent evolution- When two organisms from two different species evolve to become more alike Divergent evolution- when two organisms with the same ancestor evolve to become less similar Adaptive Radiation is when one species evolves to become several new species

28 Video co-evolution Start at 3:23 Coevolution- Bozeman Science

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31 Convergent

32 Divergent

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34 Artificial selection When humans use selective breeding to change the traits in a species (this has led to the present diversity in farm animals, pets, and garden plants) Population Genetics- the study of how gene frequencies in a group of individuals within a species changes resulting in evolution. Bell Curve- most organisms within a species will exhibit the average of any given trait within that species. Smaller numbers have the extreme of that trait creating a bell-shaped curve when graphed.

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38 Here s your bell curve

39 BR: 5 minutes Explain the differences and similarities between natural selection and artificial selection?

40 Natural selection pressures a bell curve in three ways. 1. Stabilizing selection- favors the survival and breeding success of the average of a trait resulting in the narrowing of the bell curve. 2. Directional Selection- favors the extremes of a trait resulting in the shifting of the bell curve 3. Disruptive Selection- favors both extremes of a trait but not the average. The result is the changing of one bell curve into two. (divergent evolution) Mutations- malfunctions of genetic material production, repair, maintenance, or the result of exposure, these are usually harmful but on rare occasion may actually prove beneficial.

41 Directional selection moves the average of a population one way

42 Look how directional selection has changed the Galapagos Marine Iguana

43 Disruptive selection

44 Stabilizing selection

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46 Sexual selection is the driving force which selects for traits that make organisms more sexually viable, not necessarily more survivable. Speciation- the process of evolving new species from old species Morphological Concept of Speciesorganisms that look different must be different species Biological Concept of Species-Organisms that will naturally interbreed and produce fertile offspring are within the same species.

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49 Homer the Seal- Sexual Selection

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51 Strong

52 BR: 5 minutes Explain the differences and similarities between natural selection and artificial selection?

53 Natural selection pressures a bell curve in three ways. 1. Stabilizing selection- favors the survival and breeding success of the average of a trait resulting in the narrowing of the bell curve. 2. Directional Selection- favors the extremes of a trait resulting in the shifting of the bell curve 3. Disruptive Selection- favors both extremes of a trait but not the average. The result is the changing of one bell curve into two. (divergent evolution) Mutations- malfunctions of genetic material production, repair, maintenance, or the result of exposure, these are usually harmful but on rare occasion may actually prove beneficial.

54 Directional selection moves the average of a population one way

55 Look how directional selection has changed the Galapagos Marine Iguana

56 Disruptive selection

57 Stabilizing selection

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59 Sexual selection is the driving force which selects for traits that make organisms more sexually viable, not necessarily more survivable. Speciation- the process of evolving new species from old species Morphological Concept of Speciesorganisms that look different must be different species Biological Concept of Species-Organisms that will naturally interbreed and produce fertile offspring are within the same species.

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62 Homer the Seal- Sexual Selection

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65 Color Morphs

66 Compare and contrast Sexual selection and Natural selection. Do they lead to the same result? If not, when might they lead to the same results? When would they not?

67 Founder Effect- When a gene is present at a high level in a new population then becomes more common with time Emigration- The movement of organisms and alleles out of a population Immigration- The movement of organisms and alleles into a population Gene flow- the random transfer of alleles or genes from one population to another. Genetic Drift- The change in allele frequency within a population due to the environment Assortative mating is a nonrandom mating pattern in which individuals with similar genotypes and/or phenotypes mate with one another more frequently than would be expected under a random mating pattern

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69 Five fingers of evolution

70 Populations evolve into new species when they are isolated Prezygotic isolation prevents two organisms from ever creating a fertilized egg. Geographic Isolation-Physical separation of populations by mountains, rivers, oceans, or other natural barriers. Reproductive isolation- Differences in genetics or behavior that lead to a failure of two populations to interbreed. This includes chromosome number, breeding season, breeding rituals, etc. Postzygotic isolation- Allows for fertilization of the egg to take place but the egg then fails to fully develop or it develops into an infertile organism. (Ex. Mules)

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73 Anoles

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75 Tigon

76 Liger

77 Natural selection is incorrectly characterized as survival of the fittest when it is in fact breeding success of the fittest. Four types of evidence used by Darwin include 1.Embryology 2.Paleontology 3. Biogeography 4. Morphology Law of Superposition- the further down you go in rock layers, the older the layer is and the older the fossils in it are. Genetics came into the picture after Darwin s idea was published but helped credit it as a THEORY

78 Some benchmarks include Science moved through experimentation to understand that life came from life, this idea is known as biogenesis Spontaneous generation, the production of living things from non living things is not scientifically plausible under present conditions. Organisms could not have originated in the presence of oxygen, but oxygen is necessary to protect organisms from UV light. The O2 was created by cyanobacteria within the waters of the earth. These were photosynthetic bacteria that give off oxygen which can turn into ozone creating a protective shield around the earth and resulting in the colonization of land by organisms.

79 Chemosynthesis is the production of energy rich molecules (ATP, sugars, etc.) by breaking down chemicals that are available. This allows ecosystems to develop where there is no light based food chain available. Endosymbiotic hypothesis- an explanation of how eukaryotic cells developed. Two prokaryotes meet and one engulfs the other. The larger of the two is exceptional at attaining metabolically necessary materials but does not utilize them well. The smaller of the two does not take up materials well but it does make use of available materials well and starts making so much of the preferred energy storage molecule that the two original organisms both benefit. The relationship becomes inseparable.

80 Fig Plasma membrane Ancestral prokaryote Cytoplasm DNA Endoplasmic reticulum Nucleus Nuclear envelope

81 Fig Aerobic heterotrophic prokaryote Mitochondrion Ancestral heterotrophic eukaryote

82 Fig Photosynthetic prokaryote Mitochondrion Plastid Ancestral photosynthetic eukaryote

83 Fig Plasma membrane Ancestral prokaryote Cytoplasm DNA Endoplasmic reticulum Nuclear envelope Aerobic heterotrophic prokaryote Mitochondrion Ancestral heterotrophic eukaryote Nucleus Photosynthetic prokaryote Mitochondrion Plastid Ancestral photosynthetic eukaryote

84 Phenotype vs. Genotype Phenotype- is the trait Genotype- is the alleles for that trait

85 Phenotypic ratio in a population = Recessive trait =Dominate trait Phenotypic ratio= Red Hair 5/10, Blonde 5/10 Genotypic Ratio=?????

86 Genotypic ratio in a population Phenotypic ratio= Red Hair 5/10, Blonde 5/10 Genotypic Ratio= Red Alleles 12/20, Blonde 8/ Gene pool- all of the genes in any population.

87 Hardy-Weinberg Equilibrium defines a population that is at equilibrium or NOT Evolving. Five things must be true for this to happen 1. No natural selection 2. You must have a very large population 3. Random mating only 4. No gene flow 5. No mutations occur p 2+ 2(pq)+q 2 =1 is the Hardy Weinberg equation which identifies the allele and genotype prevalence if a species only exhibits two alleles p= dominate allele frequency (blonde in our last ex.) q= recessive allele frequency (red in our last ex.)

88 Where do we get this formula? p 2 +2pq+q 2 =1 Suppose we have a population where the Dominate allele is 60% of the alleles and the recessive allele is 40% of the alleles p=0.6 q=0.4 p=0.6 =06* =0.4* q=0.4 =0.4* =0.4*

89 Hardy Weinberg requires two things to happen. 1. The sum of all allele frequencies=1 2. The sum of all genotype frequencies =1 homozygous heterozygous homozygous dominant recessive p 2 + 2(pq) + q 2 = 1 Dominant Alleles Recessive Alleles p+q=1

90 Four percent of humans on the planet have red hair, what percentage of humans on the planet are heterozygous for this trait? q 2 =0.04, thus.. q= 0.2 p+q=1.. So p=0.8 Example problem 1 Heterozygous individuals are 2(pq) 2(0.8)(0.2)=0.32 or 32% of people are heterozygous.

91 Example problem 2 You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: a) The frequency of the "aa" genotype. b) The frequency of the "a" allele. c) The frequency of the "A" allele. d) The frequencies of the genotypes "AA" and "Aa."

92 Within a population of butterflies, the color brown (B) is dominant over the color white (b). And, 25% of all butterflies are white. Given this simple information, which is something that is very likely to be on an exam, calculate the following: 1. The percentage of butterflies in the population that are heterozygous. 2. The frequency of homozygous dominant individuals.

93 4) A very large population of randomly-mating laboratory mice contains 49% white mice. White coloring is caused by the double recessive genotype, "aa". Calculate allelic and genotypic frequencies for this population.

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