Bio11 Notes: Taxonomy & Evolution PDF

Taxonomy & Evolution Notes #1: Taxonomy Notes #2: Five Kingdoms Notes #3: Dichotomous Keys Notes #4: Phylogeny Notes #5: DNA Notes #6: DNA’s Role In Evolution: Variation Notes #7: Agents of Evolutionary Change Notes #8: Adaptations Notes #9: Speciation Notes #10: Pattern...

Taxonomy & Evolution Notes #1: Taxonomy Notes #2: Five Kingdoms Notes #3: Dichotomous Keys Notes #4: Phylogeny Notes #5: DNA Notes #6: DNA’s Role In Evolution: Variation Notes #7: Agents of Evolutionary Change Notes #8: Adaptations Notes #9: Speciation Notes #10: Patterns & Rate of Evolution #1) Taxonomy  Taxonomy Taxonomy is the science of identifying, naming, and classifying organisms.  Carolus Linnaeus (1753) Carolus Linnaeus’s contributions to taxonomy: 1) Two-word naming system called binomial nomenclature 2) Hierarchical classification system using categories called taxa based on physical characteristics  Binomial Nomenclature 1) Written in italics 2) The first name (genus) is capitalized 3) The second name (species) is lowercased Common name: Grizzly Bear Scientific name: Ursus arctos  Linnaean Classification Linnaeus’s system of classification includes seven hierarchical taxa (from largest to smallest): kingdom, phylum, class, order, family, genus, species In 1977, Carl Woese introduced a new taxon: domain Before 1977 After 1977 Example of Taxonomic Classification general specific #2) Five Kingdoms  The Five Kingdoms 1) Monera -Eubacteria -Archaebacteria 2) Protista 3) Fungi 4) Plantae 5) Animalia  Kingdom Monera (Eubacteria) Monerans of the Domain Eubacteria are single-celled prokaryotes known as the “true bacteria” live in most environments e.g. E. coli  Kingdom Monera (Archaebacteria) Monerans of the Domain Archaebacteria are single- celled prokaryotes known as the “ancient bacteria” or “extremophiles” live in harsh environments e.g. methanogens, halophiles, thermophiles  Kingdom Protista Protists (or Protozoans) are single-celled eukaryotes that can be animal-like, plant- like, or fungus-like e.g. Amoeba  Kingdom Fungi Fungi are mostly multicellular, eukaryotes, and are usually saprophytic (i.e. feed on dead or decaying matter) all fungi are non- photosynthetic e.g. water mould, mushroom, morel, yeast bread mould, penicillium  Kingdom Plantae Plants are mostly multicellular, eukaryotes, and are photosynthetic e.g. algae, moss, ferns, trees, flowers  Kingdom Animalia Animals are all multicellular heterotrophic eukaryotes includes all invertebrates and vertebrates #3) Dichotomous Keys  Dichotomous Keys Dichotomous keys are used to determine the identity of an organism from a series of paired statements that describe the organism’s physical characteristics.  How to Use a Dichotomous Key 1) Begin by reading the first pair of statements: 1A and 1B. 2) Decide which statement 1A or 1B correctly describes the organism, then follow the direction at the end of the statement. 3) Continuing reading the paired statements until you determine the identity of the organism Dichotomous Key Example #4) Phylogeny  Phylogeny Phylogeny is the study of evolutionary relationships. Two different diagrams are used: 1) Phylogenetic Trees 2) Cladograms  Phylogenetic Trees Phylogenetic trees show the following: 1) How descendants are related to ancestors (nearer on a branch = closer relative). 2) How much descendants have changed (longer branch = more time).  Cladograms Cladograms only show similarities in characteristics amongst species, not their ancestry.  Determining Evolutionary Relationships Evolutionary relationships can be established using the five methods: 1) Similarities in morphology 2) Biochemical relationships 3) Homologous body structures 4) Fossil record 5) Embryonic development  1) Similarities in Morphology Similarities in morphology or anatomical similarities is usually, but not always, seen in closely related species.  2) Biochemical Relationships Biochemical relationships such as DNA comparisons show greater similarities in closely related species.  3) Homologous Body Structures Homologous body structures are similar body parts of related species that are adapted for different functions (e.g. forelimb of mammals).  4) Fossil Record Fossil records can be used to determine changes in species over time.  5) Embryonic Development Embryonic development in related species (e.g. vertebrates) show similarities during early stages. (e.g. in humans, gill slits become auditory canal and various glands). #5) DNA  DNA Function DNA function: 1) Stores genetic information 2) Transmits genetic information  Discovery of DNA Structure (1953) Deoxyribonucleic Acid (DNA) structure was discovered by Watson and Crick in 1953  DNA Building Blocks The building blocks of DNA are called nucleotides Each nucleotide has three molecules: 1) deoxyribose sugar 2) phosphate 3) nitrogenous base (A, T, C, or G)  Nitrogenous Base Pairing Adenine pairs with Thymine: A–T Guanine pairs with Cytosine: G–C Purines (Adenine, Guanine) Pyrimidines (Cytosine, Thymine)  Double Helix Structure of DNA DNA is a double-stranded molecule, forming a double- helix shape. The two sugar-phosphate “backbones” of DNA are held together by hydrogen bonds between base pairs. #6) DNA’s Role in Evolution: Variation  Variation Variations are physical differences seen in individuals based on genes/genetic variation. (e.g. different heights in humans)  What Causes Variations? There are two sources of variations in a population: 1) Mutation 2) Sexual Reproduction (i.e. meiosis)  Mutation Mutations are changes in the DNA sequence due to mutagens such as radiation, chemicals, or viruses can result in new genes and traits can be positive, negative, or neutral  Sexual Reproduction (i.e. meiosis) During meiosis, new combinations of genes/traits can be created in eggs and sperm due to two events: 1) Crossing-over 2) Independent Assortment  Crossing-Over Crossing over occurs during Prophase I when homologous chromosomes pair up and exchange DNA.  Independent Assortment Independent assortment of genes is due to the random orientation and pairing of homologous chromosomes during Metaphase I. #7) Agents of Evolutionary Change  What is Evolution? Definition #1 (Classic) Definition #2 (Genetic) Modern organisms Changes in the frequency of descending from ancient certain genes in a organisms. population.  Agents of Evolutionary Change 1*) Mutation 2) Genetic drift – founder effect 3) Genetic drift – bottleneck effect 4) Gene migration/Gene flow 5) Non-random mating – sexual selection 6) Non-random mating – inbreeding 7) Artificial selection 8) Natural selection *Source of new genes.  1*) Mutation Mutation of DNA is the source of new genes.  2) Genetic Drift – Founder Effect Genetic Drift is the change in frequency of genes (alleles) due to random chance. The Founder Effect occurs when a few individuals colonize a new area.  3) Genetic Drift – Bottleneck Effect The Bottleneck Effect occurs when there is a reduction in population size due to environmental events (e.g. natural disaster, famine, disease).  4) Gene Migration/Gene Flow Gene Migration (or gene flow) is the movement and introduction of genes from one population to another.  5) Non-Random Mating – Sexual Selection Sexual Selection is when an individual chooses a mate with certain traits (e.g. male peacock’s tail).  6) Non-Random Mating – Inbreeding Inbreeding is when individuals mate and reproduce with close relatives.  7) Artificial Selection Artificial Selection is humans selecting desirable traits in individual organisms and selectively breeding them.  8) Natural Selection Natural Selection is the process by which individuals better adapted to their environment survive and pass on their genes to their offspring. (e.g. peppered moth) Before industrial revolution During industrial revolution #8) Adaptations  Adaptations Adaptations are inherited characteristics that increase an organism’s chance of surviving and reproducing. Over time, organisms accumulate beneficial adaptations through the process of natural selection. Three types of adaptations: 1) Anatomical 2) Physiological 3) Behavioural  Anatomical Adaptation Anatomical adaptation – inherited physical feature (e.g. Narwhal’s tusk in males)  Physiological Adaptation Physiological adaptation –inherited process that controls life activities (e.g. bear hibernation: lowers body temp, breaks down fat)  Behavioural Adaptation Behavioural adaptation – inherited instinct or capacity for learning (e.g. social grooming in monkeys) #9) Speciation  What is a Species? A species is a group of organisms that can breed with one another and produce fertile offspring.  Factors Keeping Species Distinction 1) Different number of chromosomes (e.g. donkeys: 62, horses: 64, mules: 63). Mules are infertile hybrids. 2) Different mating or courtship patterns or behaviours 3) Different breeding seasons 4) Incompatibility of egg and sperm  Hybrids (infertile offspring) Wholphin Cama Tigon Coywolf Zorse Beefalo  Speciation Speciation is the process of new species evolving from old ones. e.g. Darwin`s Finches: 1) Founders arrive 2) Geographic isolation 3) Changes in the gene pool 4) Reproductive isolation 5) Competition 6) Continued evolution 1) Founders Arrive 2) Geographic Isolation 3) Changes in the Gene Pool Example: Beak Differences 4) Reproductive Isolation 5) Competition 6) Continued Evolution Darwin`s Finches #10) Patterns & Rate of Evolution  Patterns of Evolution Large-scale evolutionary patterns and processes occur over long periods of time: 1) Mass Extinction 2) Adaptive Radiation (Divergent Evolution) 3) Convergent Evolution 4) Parallel Evolution 5) Coevolution 6) Mimicry  1) Mass Extinction Mass extinction of species leaves environments open for the survivors to fill. e.g. 65 million years ago: The extinction of the dinosaurs cleared the way for the evolution of modern mammals and birds.  2) Adaptive Radiation (Divergent Evolution) Adaptive Radiation occurs when an ancestral species evolves into several new species by adapting to a wide range of environment. e.g. Darwin’s Finches  3) Convergent Evolution Convergent Evolution occurs when unrelated species evolve similar traits called analogous structures. e.g. streamlining in fish, reptiles, mammals, and birds  4) Parallel Evolution Parallel Evolution occurs when related species evolve similar traits. e.g. placental and marsupial mammals  5) Coevolution Coevolution occurs when two species evolve in response to each other. e.g. orchid and hawk moth  6) Mimicry Mimicry occurs when one species evolves to look like another. e.g. stick bug mimicking a leaf  Rate of Evolution Gradualism Model – evolution Punctuated Equilibrium Model occurs slowly and steadily – evolution occurs in spurts (e.g. after mass extinction)