Ch. 12 Evolution & Ch. 13 Adaptation & Speciation
Unit 10: Evolution Ch. 12 Evolution & Ch. 13 Adaptation & Speciation The Most Astounding FactDr. Neil DeGrasse Tyson 300 History of Earth How old is Earth? What was early Earth like?
~4.6 billion years old What was early Earth like? hostile...a lot of volcanic activity & lightning,many meteorite impacts,high levels of UV light What gases were in the primitive atmosphere? methane, ammonia, hydrogen, water vapor What gas was missing? oxygen Alexander Oparin1936: proposed primitive atmosphere contained: methane, ammonia, hydrogen, water vapor Whats missing? oxygen Origin of Life When did life 1st appear?
~3.5 billion years ago What did Miller & Urey do in their experiment? simulated primitive atmosphere & zapped it with electricity What happened? ~1 week amino acids & other simple organic molecules formed (in water) precursors to 1st cells 1953 electricity (similar to lightning in atmosphere) water (similar to ocean)! The First Organisms: Heterotrophs
What does the Heterotroph Hypothesis or Primordial Soup Hypothesis state? simple compounds formed 1st complex compounds primitive pre-cells prokaryotes (1st cells were heterotrophs) Why heterotrophic? b/c no O2 for cellular respiration What did they feed on? naturally organic material (primordial soup) in ocean (ex. amino acids) Similar to some present-day bacteria, they obtained energy from simple chemical reactions. heterotrophs (could not produce their own food) Why not?Used chem in surroundings for energy no oxygen for cellular respiration, which would be used to break the bonds in glucose made during psyn instead fed on the organic material from the primordial soup (in oceans); give this theory its name As a group, these bacteria are calledheterotrophic anaerobes(ann-air-robes). Because there was virtually no oxygen in the atmosphere at this time, these bacteria were necessarily anaerobic, meaning they did not breathe oxygen.Heterotrophs, meaning "other feeders", are simply organisms that cannot make their own food. So "heterotrophic anaerobes" means they were creatures which ate some naturally occurring food and did not breathe oxygen. Thefossilsof some these oldest known forms of life have been found in Australian rocks dating back 3.5 billion years.To create energy, these early bacteria probably consumed naturally occurring amino acids. Later Organisms: Autotrophs
What type of organisms followed the prokaryotic heterotrophs? prokaryotic autotrophs What did they release into the atmosphere? oxygen (.causing the oxygen revolution!) Why was oxygen so important? allowed development of eukaryotes & complex organisms stromatolites Stromatolites are the oldest known fossils, dating back more than 3 billion years. They are colonial structures formed by photosynthesizing cyanobacteria and other microbes. Stromatolites are autotrophic prokaryotes that thrived in warm aquatic environments and built reefs much the same way as coral does today. Cyanobacteria were likely responsible for the creation of earth's oxygen atmosphere. They were the dominant life form on Earth for over 2 billion years. Today they are nearly extinct, living a precarious existence in only a few localities worldwide What is Evolution? theory that species/populations change over time
Can an individuals genes change? No Can a populations gene pool (total genes) change? Yes when allele frequencies (%) change due to natural selection Scientific theories are explanations that are based on lines of evidence, enable valid predictions, and have been tested in many ways. Evolution does not explain the origin of life, only how it changed once it got here. Gene pool: the entire collection of genes among a populationEach new offspring in a population draws its genes from the same gene pool. Allele frequencies % of an allele in a population (determines frequencies of genotypes & phenotypes in populations) EVOLUTION does not occur w/ a purpose certain features are not developed in order to adapt to change in env. Variation exists in population (usually due to random mutation &/or sexual reproduction) & certain variations become useful when env changes the organisms w/ the best-suited variations survive & produce offspring while others dies before they can reproduce in this way a population/species becomes adapted to its environment 4 Mechanisms (Causes) of Evolution
1.How does migration cause evolution? gene frequencies change as individuals move in or out of the population 2. How does genetic drift cause evolution? pure CHANCE causes a change in gene pool of a small population Mechanisms methods/means by which evolution occurs genetic drift, a change in the gene pool of a small population that takes place strictly by chance Migration Some individuals from a population of brown beetles might have joined a population of green beetles. That would make genes for brown coloration more frequent in the green beetle population than they were before the brown beetles migrated into it. Genetic drift Imagine that in one generation, two brown beetles happened to have four offspring survive to reproduce. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation but just by chance. These chance changes from generation to generation are known as genetic drift. 4 Mechanisms of Evolution
3. How does mutation cause evolution? random changes in DNA sequence can change amino acid sequence & protein coded for & can change how the trait is expressed Do all mutations matter in evolution? No to matter they must be in gametes able to be passed down (heritable) Mechanisms methods/means by which evolution occurs genetic drift, a change in the gene pool of a small population that takes place strictly by chance Mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make genes for brown coloration more frequent in the population than they were before the mutation. 4 Mechanisms of Evolution
4. How does natural selection cause evolution? organisms with the variation best suited for environment (adaptation) tend to survive, & reproduce more (survival of the fittest) What will that cause? favorable adaptation will be passed to more offspring than before acts on individuals, BUT causes evolution of population Mechanisms methods/means by which evolution occurs genetic drift, a change in the gene pool of a small population that takes place strictly by chance Which trait was a better adaptation and selected for? How were frequencies of different alleles affected? Natural selection Imagine that green beetles are easier for birds to spot (and hence, eat). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation. Example of Natural Selection Pepper Moths EnglandOriginal color 99% white (trees light bark)Industrial Revolution, 1850s produced smog Enviro. changes s -99% black (trees dark bark) 4 Mechanisms of Evolution
Which trait was a better adaptation and selected for? Mechanisms methods/means by which evolution occurs genetic drift, a change in the gene pool of a small population that takes place strictly by chance Which trait was a better adaptation and selected for?How were frequencies of different alleles affected? Natural selection Imagine that green beetles are easier for birds to spot (and hence, eat). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation. Example of Natural Selection Pepper Moths EnglandOriginal color 99% white (trees light bark)Industrial Revolution, 1850s produced smog Enviro. changes s -99% black (trees dark bark) How were frequencies of different alleles affected? Explanations for How Evolution Happens
What did Jean Baptist Lamarck propose about how evolution occurred? Theory of Acquired Characteristics (use vs. disuse) acquired traits are passed on & leads to changes in species Proposed that nature drove organisms from simple to increasingly complex forms Did experimentation support Lamarcks thinking? no Proclaimed that all species, including our own, are descended from other species Inheritance of Acquired characteristicsthought that modifications acquired during the life of an organism could be passed on to offspringClassic example long neck of the giraffe could acquire longer necks by reaching for leaves on higher branches & would pass this characteristics on to their offspringEx. Tattoo would be passed on. Also proposed use vs. disuseOrgans became stronger with use Changes due to use or disuse could be then transferred to offspringBody parts used extensively to cope w/ environment became larger & stronger, while those not used deteriorated This sort of evolution, for which Lamarck is most famous today, was only one of two mechanisms he proposed. As organisms adapted to their surroundings, nature also drove them inexorably upward from simple forms to increasingly complex ones. Explanations for How Evolution Happens
Charles Darwin (naturalist on HMS Beagle) What did he do on his trip? collected fossils & specimens observed tremendous biodiversity noticed unique organisms similar to organisms in other parts of world determined they were all related desert large rainfall intermediate shell domed Shell saddle- backed shell Climate varied from island to island. Charles Darwin ( )naturalist on HMS Beagle (1831-6) noticed unique organisms that were similar to organisms in other parts of the worldDarwin determined that these organisms were all relatedFormulated his idea of Descent with Modification (changes occur from one group of descendants to the next) organismsthat are adapted to their environments must also change to remain adapted Saddlebacklong neck, curved shell, found on Hood Island, Dome-shapedshorter neck, domed shell, lush vegetation, covers the ground, Isabela island Explanations for Evolution
What did Darwin conclude from his observations? life forms can & do change. but, questioned how this change occurred answers pointed to evolution or descent with modification needed to test ideas before explaining how or why such changes happen Studied Charles Lyell geologist The present is the key to the past.The same forces acting on earth in the past are continuing today. Clear to Darwin that organisms adapted to their environments must also change to remain adapted. Animals and plants were well adapted to different environments of diff islands! Questioned how this change occurred ~answers pointed to evolution or descent with modification (structural or functional changes occur from one group of descendents to the next)Darwin envisioned the tree of life Phylogenetic Tree Explanations for Evolution
When thinking about HOW evolution happened, Darwin noted artificial selection (selective breeding) plan/goal = to produce preferred offspring Darwin wondered, Is there a force in nature that simulates artificial selection??? Choose parents w/ desired traits to breed together Darwin reasoned that if we could artificially select traits, then the same process should occur naturally Evolution is different b/c relies on variation & chance w/o human interference Darwins Explanation: Natural Selection
What were the 4 main points Darwin used to explain how evolution occurred? Overproduction of offspring Struggle to survive (competition for existence) Variation within population Successful reproduction (survival of the fittest/ best adapted organisms are naturally selected) 1859 Trick to remember Overproduced variations struggle to successfully reproduce In his book On the Origin of Species by Means of Natural Selection (1859) Darwin explained how/why changes in populations occurred By early 1840s Darwin developed major features of theory of natural selection as mechanism for evolution. Reluctant to publish, continued to compile evidence1858, Alfred Wallace, naturalist working in East Indies, sent Darwin manuscript containing a theory of natural selection essentially identical to Darwins.Did not know Darwin had been developing a theory of the process behind evolutionLater that year, both Wallaces paper and extracts of Darwins essay were presented to the Linnaean Society of London.Darwin quickly finished The Origin of Species and published it the next year.While both Darwin and Wallace developed similar ideas independently, the essence of evolution by natural selection is attributed to Darwin because he developed and supported the theory of natural selection earlier and much more extensively. Video:Who Was Charles Darwin? Darwins Explanation: Natural Selection
Overproduction of offspring Why is this necessary? to ensure that at least some offspring will survive long enough to reproduce & pass on genes Upon his return from England Darwin read an essay by Thomas Malthus.Malthus warns that the human population is increasing too quickly for the planet.Larger the population gets larger the rate of reproduction W/ pop growth comes competitionMalthusconcludes dont worry it will fix itself!How?/Why? Overproduction many offspring produced die before reaching maturity due to competition for scarce resources, illness, starvation, etc. How would these ideas have influenced Darwins thinking?Darwin extended idea to other organisms.realized struggle for existence/competitionSurvivors usually those best suited for environment (fittest) Darwins Explanation: Natural Selection
Over production leads to the struggle to survive How? more organisms than resources to go around leads to competition (idea based on work of Thomas Malthus) Organisms compete for? food, shelter, mates, space, light, water, nutrients, etc. Population levels off at the carrying capacity. maximum # that can be supported given available resources Video: Darwin & Malthus a.k.a. struggle for existence Survivors Who are they? Individuals w/ variations for traits adaptive for their environment that time) have a better chance of survival, & thus, leave more offspring How did they get these traits? By chance. (usually due to random mutation &/or sexual reproduction) Were these traits a response to their environment? NO certain features are NOT developed in order to adapt to changes in the envit just so happens that certain variations become useful when env changes The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. Upon his return from England Darwin read an essay by Thomas MalthusMalthus warns that the human population is increasing too quickly for the planet.Larger the population gets larger the rate of reproduction W/ pop growth comes competitionMalthusconcludes dont worry it will fix itself!How?/Why? Overproduction many offspring produced die before reaching maturity due to competition for scarce resources, illness, starvation, etc. How would these ideas have influenced Darwins thinking?Darwin extended idea to other organisms.realized struggle for existence/competitionSurvivors usually those best suited for environment (fittest) Darwins Explanation: Natural Selection
The survivors of the struggle to survive Who are they? individuals w/ variations that are best suited for that particular environment (adaptations) How do they get these traits? chance & variation unlike artificial selection which has plan/goal Were these traits a response to their environment? NO it just so happens that the variation is beneficial & allows for increased survival & reproduction of more offspring with that trait (due to natural selection for that trait) camouflage a.k.a. struggle for existence Survivors Who are they? Individuals w/ variations for traits adaptive for their environment that time) have a better chance of survival, & thus, leave more offspring How did they get these traits? By chance. (usually due to random mutation &/or sexual reproduction) Were these traits a response to their environment? NO certain features are NOT developed in order to adapt to changes in the envit just so happens that certain variations become useful when env changes The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. Upon his return from England Darwin read an essay by Thomas Malthus.Malthus warns that the human population is increasing too quickly for the planet.Larger the population gets larger the rate of reproduction W/ pop growth comes competitionMalthusconcludes dont worry it will fix itself!How?/Why? Overproduction many offspring produced die before reaching maturity due to competition for scarce resources, illness, starvation, etc. How would these ideas have influenced Darwins thinking?Darwin extended idea to other organisms.realized struggle for existence/competitionSurvivors usually those best suited for environment (fittest) Darwins Explanation: Natural Selection
Variations can be adaptations. traits that make an organism better able to survive in its environment Ex. Desert adaptations for temp extremes & water availability EVOLUTION does not occur w/ a purpose certain features are not developed in order to adapt to change in env. Variation exists in population (usually due to random mutation &/or sexual reproduction) & certain variations become useful when env changes the organisms w/ the best-suited variations survive & produce offspring while others dies before they can reproduce in this way a population/species becomes adapted to its environment BRIDGING THE GAP in teachers edition of 200 book How do you explain a dark mouse producing offspring that are light? GENES control mouse color thus, a certain gene combo in offspring can result in light color (genetic variation) Can the dark mouse control the type of color in its offspring? NO, the sorting out of traits is a random event occurring during meiosis Darwins Explanation: Natural Selection
Contractile Vacuole Video Variations can be adaptations. traits that make an organism better able to survive in its environment Ex. Desert adaptations for temp extremes & water availability EVOLUTION does not occur w/ a purpose certain features are not developed in order to adapt to change in env. Variation exists in population (usually due to random mutation &/or sexual reproduction) & certain variations become useful when env changes the organisms w/ the best-suited variations survive & produce offspring while others dies before they can reproduce in this way a population/species becomes adapted to its environment BRIDGING THE GAP in teachers edition of 200 book How do you explain a dark mouse producing offspring that are light? GENES control mouse color thus, a certain gene combo in offspring can result in light color (genetic variation) Can the dark mouse control the type of color in its offspring? NO, the sorting out of traits is a random event occurring during meiosis Darwins Explanation: Natural Selection
In any given population, there will be a variation within a trait. What causes variety? Sexual reproduction b/c combining genes from 2 genetically different parents speeds up evol b/c increase genetic variety Crossing over during meiosis causes new arrangement of genes on chromosomes Arrangement of chromosomes (alleles) during meiosis affects how chromosomes sort into gametes Mutations random changes in genes Variation exists among all groups of organisms.Individuals w/ variations for traits adaptive for their environment have a better chance of survival, & thus, leave more offspring b/c variations can be inherited, many offspring will have those same traits Organisms lacking those traits are less likely to survive & tend to leave fewer offspring over time, the population consists only of adapted organisms (until environment changes) What we know about genetics today supports Darwins theory of natural selection Darwins Explanation: Natural Selection
What causes variations within a population? Sexual reproduction Crossing over during meiosis Arrangement of chromosomes during meiosis (independent assortment) Mutations Sexual repro. & meiosis speed up evolution increases variety Darwin did NOT have knowledge of genetics! What causes variety? Sexual reproduction b/c combining genes from 2 genetically different parents speeds up evol b/c increase genetic variety Crossing over during meiosis causes new arrangement of genes on chromosomes Arrangement of chromosomes (alleles) during meiosis affects how chromosomes sort into gametes Mutations random changes in genes Variation exists among all groups of organisms.Individuals w/ variations for traits adaptive for their environment have a better chance of survival, & thus, leave more offspring b/c variations can be inherited, many offspring will have those same traits Organisms lacking those traits are less likely to survive & tend to leave fewer offspring over time, the population consists only of adapted organisms (until environment changes) What we know about genetics today supports Darwins theory of natural selection Darwins Explanation: Natural Selection
How does natural selection lead to successful reproduction? Those organisms best suited for environment tend to survive, reproduce, & pass on genes (survival of fittest) more offspring have favorable adaptation than before Example of Natural Selection Pepper Moths EnglandOriginal color 99% white (trees light bark)Industrial Revolution, 1850s produced smog Enviro. changes s -99% black (trees dark bark) Darwins Explanation: Natural Selection
Ex. Pepper Moths England Original color 99% white (trees w/ light bark) Industrial Revolution, 1850s produced soot Enviro. changes s -99% black (trees w/ dark bark) Pepper Moth Game Principles of Natural Selection "Interactive" Darwins Explanation: Natural Selection Divergent evolution Finches on different islands ate different foods beak adaptations that helped them gain more food (& thus survive & reproduce) were selected for & passed on to offspring. Eventually causing adaptive radiation so that birds on different islands had beaks that were more suited to the type of food available on that island (other beak types that were not well adapted to that food type were selected against) Adaptive Radiation Hawaiian Honeycreepers Divergent evolution How would Darwin adjust the description given by Lamarck about the length of giraffes necks?
Lamarck vs. Darwin Darwin would say that its not b/c the giraffe keeps stretching that necks get longer over time, but that within the population, there is variation in neck length & that those giraffes w/ longer necks are better suited to their env & getting food off the tops of trees. Therefore, they are able to survive better, reproduce more, & pass on their genes (compared to those w/ short necks) over time, more individuals have the genes for longer necks b/c selected for (due to successful reproduction) Darwins Explanation: Wallaces Same Conclusion
Who was Alfred Wallace (1858)? naturalist that arrived at same basic explanation as Darwin However, Darwin usually given credit but BOTH men should be credited By early 1840s Darwin developed major features of theory of natural selection as mechanism for evolution. Reluctant to publish, continued to compile evidence 1858, Alfred Wallace, naturalist working in East Indies, sent Darwin manuscript containing a theory of natural selection essentially identical to Darwins.Did not know Darwin had been developing a theory of the process behind evolutionLater that year, both Wallaces paper and extracts of Darwins essay were presented to the Linnaean Society of London.Darwin quickly finished On the Origin of Species and published it the next year.While both Darwin and Wallace developed similar ideas independently, the essence of evolution by natural selection is attributed to Darwin because he developed and supported the theory of natural selection earlier and much more extensively. Indirect Evidence to Support the Theory of Evolution: Fossil Record
evidence of: change in organisms over time age of the Earth Which layer is youngest? oldest? Explain Law of Superposition Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Fossils once living remains of organisms traces or impressions of organisms from the past, mineralized in sedimentary rocks Fossils w/in layers show that a succession of organisms have populated Earth throughout time. Evidence of change over timetypes of organisms change from one layer to the next in general, simpler body structures found in older layers & more complex structures found in younger/more recent layers However, many of the simpler life forms still exist Fossil record is limited b/c Decomposition often occurs rapidlyto be fossilized must be covered in sediment as quickly as possible (this is why more fossils of shells & aquatic organisms)Exceptions frozen, dried, anoxic environment fossilization is affected by type of material preserved (bone, shell, impressions, amber) hard parts preserve better 3. Fossil record is incompleteWhy? b/c not all organisms are fossilized, not all fossils are found 4. Easily disrupted Why? some are destroyed by nature/people. Principle of original horizontality (sedimentary) rock layers deposited horizontally & stay that way unless disrupted by outside force Law of superpositionNicolaus Steno layer on bottom was deposited 1st as move up, layers become younger youngest layer on top Correlation matching up of layers & fossils (ex. across river..) Indirect Evidence to Support the Theory of Evolution: Fossil Record
Why is the fossil record limited? decomposition type of material What fossilizes best? hard parts. teeth, bones, scales incomplete record Why? not all organisms are fossilized not all fossils are found easily disrupted some are destroyed by natural processes or people Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Fossils once living remains of organisms traces or impressions of organisms from the past, mineralized in sedimentary rocks Fossils w/in layers show that a succession of organisms have populated Earth throughout time. Evidence of change over timetypes of organisms change from one layer to the next in general, simpler body structures found in older layers & more complex structures found in younger/more recent layers However, many of the simpler life forms still exist Fossil record is limited b/c Decomposition often occurs rapidlyto be fossilized must be covered in sediment as quickly as possible (this is why more fossils of shells & aquatic organisms)Exceptions frozen, dried, anoxic environment fossilization is affected by type of material preserved (bone, shell, impressions, amber) hard parts preserve better 3. Fossil record is incompleteWhy? b/c not all organisms are fossilized, not all fossils are found 4. Easily disrupted Why? some are destroyed by nature/people. Principle of original horizontality (sedimentary) rock layers deposited horizontally & stay that way unless disrupted by outside force Law of superpositionNicolaus Steno layer on bottom was deposited 1st as move up, layers become younger youngest layer on top Correlation matching up of layers & fossils (ex. across river..) Indirect Evidence to Support theTheory of Evolution: Comparative Anatomy
compares structures of different organisms living today homologous structures analogous structures vestigial structures Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Indirect Evidence to Support theTheory of Evolution: Comparative Anatomy
1. What are homologous structures? similar structures with modifications (ex. location & arrangement of bones) Which are evidence of ? a common ancestor later organisms becoming more different (divergent evolution) Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Homologous Structures Parts on different organisms that are similar in structure w/ some variations/modifications (and often similar function) and seem to indicate common origin common ancestor.Ex. bones of arm, wing, fin, & foreleg. Indicate divergent evolution things becoming more different. 2. What are analogous structures?
Indirect Evidence to Support theTheory of Evolution: Comparative Anatomy 2.What are analogous structures? different structure, but same function (ex. wings made of different materials bird = bone vs. insect = chitin) Which are due to? similar environment/use but do NOT have common ancestor later organisms become more similar (convergent evolution) Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Unrelated organisms look similar b/c of common environmental conditions, but structure itself is different Ex. wing of bird has bones, wing of insect does not, but both are used for flight becoming more similar due to convergent evolution (b/c similar environment/use) Indirect Evidence to Support theTheory of Evolution: Comparative Anatomy
3. What are vestigial structures? structures with reduced size or function that often have no apparent use Which are evidence that? species has changed Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime How does embryonic development provide evidence for evolution?
Indirect Evidence to Support theTheory of Evolution: Comparative Embryology How does embryonic development provide evidence for evolution? early stages very similar later stages more distinction What does this tell us? organisms inherited same basic body plan from common ancestor greater # similar stages more closely related Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Pic. Fish, salamander, tortoise, chick hog, cat, rabbit, human (all mammals) Indirect Evidence to Support theTheory of Evolution: Comparative Biochemistry
What codes for similar organic compounds (ex. amino acids & proteins)? similar DNA DNA most reliable form of evidence What is the significance of 2 very different speciessharing large amounts of the same DNA? evidence of common ancestry higher %, more closely related Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime Hemoglobin protein in red blood cells that carries oxygen Cytochrome c is a protein used in cellular respiration Phylogeny = Evolutionary history of a living organism based on such factors such as fossil evidence & biochemical comparisons Relationships shown through phylogenetic tree Direct Evidence to Support the Theory of Evolution: Observation
Ex. of rapid evolution that allow us to observe evolution? antibiotic- resistant bacteria MRSA pesticide-resistant insects Resistance already present in some individuals (variation) resulting from mutation Indirect dont/cant actually see happening generally happens over very long periods Direct see happening. Generally can happen w/in a few generations/a persons lifetime rapid usually within a few decades (seen w/in a humans lifetime) antibiotic resistant bacteria MRSA (Methicillin-resistant Staphylococcus aureus) Evolution & Classification
Evolutionary relationships are the basis of classification closely related share more groups (similar classification) black bear & brown bear same down to genus distantly related share fewer groups (dissimilar classification) snake & brown bear same only to phylum DOMAINEukaryota from Domain down, each level has a new set of criteria that must be shared Ex in pic. Domain all have nucleus, kingdom all are animals (have nucleus AND multicellular heterotrophs that do not have cell walls), phylum all have spines/backbones (and are animals with have nucleus AND multicellular heterotrophs that do not have cell walls), class all give birth to live young, feed the young milk, are covered w/ fur, have mammary glands (AND have spines/backbones (and are animals with have nucleus AND multicellular heterotrophs that do not have cell walls). Order eat meat. AND.. Every characteristic from above