BIOL 120 Evolution Study Guide
BIOL 120 Evolution Study Guide BIOL120
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This 9 page Study Guide was uploaded by Julia Delaluz on Thursday April 7, 2016. The Study Guide belongs to BIOL120 at Towson University taught by Dr.Partain in Winter 2016. Since its upload, it has received 16 views. For similar materials see Principals of biology in Biology at Towson University.
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Date Created: 04/07/16
Diversity & Unity of Life Evolutionary Theory: o Today scientists agree that all living things on earth share a common ancestor o All existing types of life today developed from said common ancestor o The differences arose from differences in environments, and by chance The Tree of Life, Taxonomy & Diversity Theory of Common Descent: o The common ancestor is like a tree trunk o Current species = top branches o Major groupings = more recent divergences o Closer branches = the more two species are related o Lower branches = long ago o Higher branches = more recent DNA comparison can determine species’ relatedness Biological classification- scientists attempt to organize bio-diversity into discrete and logical categories (KPCOFGS) o Kindgom, Phylom, Class, Order, Family, Genus, Species- scientific name 3 Domains: Bacteria, Archaea, Eukarya o Bacteria: single celled, make on food, prokaryotic ex: salmonella, ecoli o Archaea: prokaryotes, most single celled, mostly stationary, extremophiles o Eukarya: Contains 4 Kingdoms… o Protista: most single-celled, some plant-like (algae) animal- like(amoeba) or fungi-like(Chytrid) o Fungi: multicellular, reproduce by spores, rely on other organisms for food, body made up of hyphae (mushrooms, mildew, yeast) o Plantae: multicellular, make own food, largely stationary o Animalia: multicellular, rely on other organisms for food, mobile for at least part of life cycle The Classification of Life (table) Linnaean Classification of Humans: Cladogram: What is Evolution? A process of change in characteristic of a population of organisms over generations Evolutionary Theory o All species present today are descendants of a common ancestry and represent millions of years of microevolution through natural selection Collectively- all the changes that transform life on earth o Produces a wide diversity of organisms A genetically based phenotypic change in population of organisms over successive generations Evidence for Evolution Fossils- radiocarbon dating used to determine age of fossils Comparative anatomy Comparative embryology Biogeography Molecular biology Evidence from Biogeography Biogeography: pattern of distribution of species on the continents o support common descent. Also plate tectonics influence distribution o Species more closely match those that are geographically nearby, even when the environments for the two differ a good deal Taxonomy is based on: DNA: the more closely related the DNA, the more closely related the organisms Homology: common structures in differing organisms that may result from common ancestry Evidence of Homology Homology: the similarity in characteristics resulting from common ancestry o Test can help determine if Linnaean classifications are correct about similarities between organisms (ex: humans & chimps) o Behavior, DNA, and anatomy can be observed and tested Divergence: comparable body parts became modified in different ways in different lines of descent from a common ancestor o Same structure, looks different b/c different function o Ex: sea lion flipper bones, human arm bones Convergence: different structure, but looks similar b/c same function o Ex: bat wings, eagle wings Vestigial traits: useful in other animals, useless in others (used to be useful) o Ex: tailbone- useful in primates, useless in humans Using Molecules to Track Evolution Molecular Clock Hypothesis o Used to calculate the time of origin on one lineage relative to others, o States that the rate of change in some DNA sequences seems to be relatively constant “The Great Chain of Being”- Aristotle o Puts forth that the universe is perfect and there is no change. All species are in order, from the “lowest” (worms) to “highest” (humans) Linnaeus “Father of Taxonomy” early 1700s Classified species, believed in unchanging order of life created by God 2 Kingdoms: animalia, vegetabilia. KPCOFGS Based on shared physical similarities, Binomial nomenclature Charles Darwin o Promoted theory of evolution mid-1800s, went on Voyage of the Beagle o 1859 “On the Origin of Species”- how does evolution occur? Galapagos o After voyage, Darwin concluded that different subspecies on different islands must have evolved form a single ancestral population o Hypothesis of common descent- all modern organisms are descendent from a single common ancestor Main point is hypothesis proposing how species come about- the process of evolution through natural selection Also presents evidence in support of the common descent theory Evolution & Darwin’s Observations Based on observations, Variation within a species, TIME Characteristics are inherited, Many offspring born, not all live to reproduce Some offspring have characteristics that give them good survival chance Observation #1: o Individuals within populations vary: Observation #2: o Some variation among individuals can be passed on to their offspring (heritability): Observation #3: o Populations of organisms produce more offspring than will survive: Observation #4: o Survival and Reproduction are not Random: Fitness: the relative survival and reproduction of one variant compared to others in the same population Adaptations: traits that increase an individuals fitness in a particular environment Individuals with high fitness have more characteristics that are appropriate for that particular environment o ‘Survival of the Fittest’- relative to climate/environment Natural selection results in the survival of individuals who are best for the current environment given the current variants in the population Darwin’s Inference Natural Selection Causes evolution o Natural selection ‘selects for’ adaptive characteristics o Individuals with high fitness reproduce more often o Those adaptive alleles are passed on more often MicroEvolution Small changes, still same species, occurs over a long time Change in allele frequencies of a population over time Gene Pool: all of the alleles in a population Populations evolve due to… o Diversity, environment… Diversity arises from… Meiosis: crossing over, independent assortment Sexual reproduction, mutations Mate selection (nonrandom mating) Migration (gene flow) Fitness: having alleles suited to an environment o The more fit, the more reproduction Sexual Selection: nonrandom mating, alleles for preferred traits prevail Production of New Alleles- 3 gene mutation types: Beneficial- bestows an advantage, confers fitness. Neutral. And Harmful- typically results in death Gene Flow- Migration Gene flow: a physical flow of alleles between populations, tends to counter genetic difference that we expect to arise through mutations & natural selection Emigration (move out) Immigration (move in) o helps keep separated populations genetically similar Genetic Drift Chance of alteration of allele frequency in a population Bottleneck Effect: disease kills off members Founder Effect: small part of the population moves to a new area and they bring only a portion of the gene pool. Can give rise to dangerous disorders Natural Selection Results from Current Environmental Conditions…Results: Directional o Traits move in a particular direction, like towards larger beak sizes Stabilizing o Extremes are selected against and the traits of the population remain the same because the average condition is the most fit Disruptive (or Diversifying) o Average condition is least fit, extremes are preferred instead Hardy-Weinberg Equilibrium States that there will be no change in allele frequencies if: o Population is large, Mating is totally random o No immigration/emigration, No mutations, no natural selection Artificial VS. Natural Selection Artificial: Humans act as environment, seen in animals (dogs) plants (crops) Natural: Depends on environment, fitness, unequal reproductive success MacroEvolution Large changes, new species, occurs over a super duper long time Species: a group of individuals that, in nature, can interbreed and produce fertile offspring by cannot reproduce with members of other species o A single species makes up an impermeable container for its gene pool 3 Conditions for Speciation (macroevolution) 1) Separation of population into 2 groups 2) Environmentally different in the 2 areas causing genetic divergence 3) Development of mechanisms for reproductive isolation Isolation of populations leads to divergent traits; migration leads to speciation Physical separation leads to Speciation Reproductive Isolation: Are viable fertile offspring produced? Temporal Isolation: o Different breeding seasons, no mating Behavioral Isolation: o No mate attraction due to behavioral differences, no mating Ecological Isolation: o Different microclimates, No mating Mechanical Isolation: o Physical incompatibility of reproductive structures o Attempted mating Gamete Isolation: o No fertilization, mating, Games don’t fuse- sperm does not penetrate egg Hybrid Inviability: o Mating, fertilization, hybrid doesn’t survive long after conception Hybrid Infertility: o Mating, Fertilization, Hybrid offspring survives, Hybrid is sterile Does Evolution Occur Gradually? Gradualism: slowly and smoothly over time (ramp) OR Punctuated Equilibrium: long static periods then quickly (staircase) Human races are not biological groups, we have never been truly isolated D I S E A S E S Communicable Diseases: Still Kill Infectious Disease, Ecological Disease Emergent Disease - completely new or has not been in an area for over 20 years Emergent & Ecological Diseases: Connection? Conservation Medicine: o How our environmental changes threaten our own health, as well as the natural communities Zoonotic Diseases: o Infectious diseases of animals that can transmit disease to humans Ex: Lyme Disease, Rabies Zika Virus From monkeys & mosquiotoes in Uganda to humans in Brazil only 20% of infected people get sick and symptoms fade quickly increasing strong evidence for birth defects makes a bee-line for the brain What Causes These Diseases? Infectious Pathogens and Agents like… o Bacteria o Prions o Viruses o Eukaryotic Pathogens Prokaryotic Cells o Bacteria reproduced using binary fission o Can happen as rapidly as every 20-30 minutes o Most common cause of infectious agents o Specific bacterial species attack specific tissues Eukaryotic Cells o Parasites: Malaria, African Sleeping Sickness, Amebic Dystentary, Giardia o Worms (Helminths) o Insects/Arachnids Non-Living Infectious Agents: o Viruses: made of protein and DNA/RNA Do not demonstrate any of the characteristics of living things Cannot be treated with antibiotics Can only be “killed” by the immune system o Viroids: made of protein RNA Only known human disease is Hepatitis D, destroys liver Disguises self as Hep B. Many plan pathogens Many plan pathogens o Prions: made of carbohydrates and protein Causes other proteins to malform & become prions As more collect, they destroy brain & nerve cells Cause no immune response. So much is unknown about these infectious agents How do they Cause Diseases? Use nutrients required by other cells, produce toxins, destroy tissue Immune System Defenses First Line: non specific response o Skin & mucous members Second Line: specific responses o White blood cells (macrophages) proteins (interferon) and inflammation Third Line: o Lymphocytes (B & T cells) o They remember the disease and how to fight it The Disease Process Asymptomatic: carrier of the disease, but does not show symptoms Incubation: disease agent multiplies Quarantine: those who have been exposed to a contagious disease but who may or may no become ill Isolation: persons who are known to be ill with a contagious disease Vector: living Fomites: non living Ways Disease is Spread: o Exposure to bodily fluids o Transmission through intermediate host o Inhalation, ingestion Vaccines VS Antibiotics Vaccines: o Prevent diseases o Causes immune system to recognize disease o Does not kill bacterial disease, but can prevent diseases caused by bacterial toxins Antibiotics: o Treats existing disease o No affect on immune system o Cannot eliminate a viral infection
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