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 Observation

4 Scientific theory- an idea that scientists are sure of, it is broad in nature and can be used to predict 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 Science- A process for gaining information, and all of the information that it has accumulated. Good science is ALWAYS: 1. Testable 2. Repeatable 3. Falsifiable 4. Published to invite Challenge

5 Hang in there, only one more slide

6 Science is better today than it has ever been because technology has greater capability than ever and communication is better resulting in greater scrutiny 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

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8 Population- a group of interbreeding individuals of the same species. 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 to be precise. On The Origin of Species by Means of Natural Selection- was published long after it was written Darwin was born Darwin is aboard the HMS Beagle Darwin finishes putting his notes together 1852 Darwin s work and Wallace s work are both presented in London to the Linnean Society 1859 Darwin publishes his work

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10 Darwin s idea is simple. 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 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

11 Fitness is a term used to identify organisms that are well adapted. 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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13 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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17 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

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22 Convergent

23 Divergent

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25 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) Experiments that duplicate early Earth conditions indicate that organic molecules could have first formed in this environment. Other evidence suggests that comets or meteors may have seeded the Earth with these molecules

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27 Coacervates and microspheres are bubblelike structures that could have provided the original opportunity for a different internal and external environment to be created. Pointed at as the possible beginnings of cell membranes. 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.

28 Here s your bell curve

29 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.

30 Directional selection moves the average of a population one way

31 Look how directional selection has changed the Galapagos Marine Iguana

32 Disruptive selection

33 Stabilizing selection

34 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 movement of genes between populations. Genetic Drift- The change in allele frequency within a population due to the environment Assortative mating-mating based on similarity, affects allele distribution but not frequency within a population

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38 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.

39 Pretty

40 Strong

41 Color Morphs

42 Populations evolve into new species when they are isolated 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. Prezygotic isolation prevents two organisms from ever creating a fertilized egg. 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.

43 Anoles

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45 Mule avec Cougar

46 Tigon

47 Liger

48 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 Embryology Paleontology 3. Biogeography 4. Morphology Genetics came into the picture after Darwin s idea was published but helped credit it as a THEORY

49 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.

50 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.

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

52 Fig Aerobic heterotrophic prokaryote Mitochondrion Ancestral heterotrophic eukaryote

53 Fig Photosynthetic prokaryote Mitochondrion Plastid Ancestral photosynthetic eukaryote

54 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

55 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

56 Hardy Weinberg requires two things to happen. 1. The sum of all allele frequencies=1 2. The sum of all genotype frequencies =1