Biology week 1 to week 5 notes
Biology week 1 to week 5 notes BIOL 1442
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This 7 page Class Notes was uploaded by Kristin O'Flaherty on Monday February 15, 2016. The Class Notes belongs to BIOL 1442 at University of Texas at Arlington taught by Dr. Roelke in Winter 2016. Since its upload, it has received 190 views. For similar materials see Evolution and Ecology in Biology at University of Texas at Arlington.
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Date Created: 02/15/16
1/20 (syllabus) noncomprehensive final full blue sheet scantron 1/22 Ch 22: Descent with Modification: A Darwinian View of Life ● Evolution: (text gives two definitions) ○ descent with modification ○ change in allele frequencies over generations over time ● process mechanisms of how organisms evolve ● pattern how organisms have evolved historically ● Evolution is the most transformative idea in all of science ○ massive resistance at first, still some today ● James Hutton (influenced Darwin) ○ gradualism (1795) ● Thomas Malthus: essay on principle of population (1795) ● Jean Baptiste Lamarck: inheritance of acquired characteristics (1809) ● George Cuvier: studies of fossils (1812) ○ catastrophism ● Charles Lyell: Principles of Geology (1830) ● Born 1809 died 1882 ● encouraged to study medicine, didn't like it ● studies religion, didn't like it ● begins to study “natural philosophy” ○ what we would call natural history ● Teacher and botanist John Henslow sends him on a Royal Navy expedition as an intellectual companion and ship’s naturalist to Captain Fitzroy ● Voyage of the HMS Beagle (18311836) ● Phylogeny ○ life has a family tree ● two observations ○ variation among organisms ○ individuals produce more offspring than the environment can support indefinitely ● two inferences ○ individuals whose inherited traits give them a higher probability of surviving and reproducing tend to leave more offspring than other individuals ○ the unequal ability of individuals to survive and reproduce leads to the accumulation of favorable traits in the population over generations ● On the Origin... (1859) ● all of Darwin’s evidence for natural selection ○ influenced greatly by the study of artificial selection ● Alfred Russel Wallace ○ codiscoverer of natural selection ■ working as a specimen collector in the Malay Archipelago (indonesia) ■ not independently wealthy lie Darwin nor connected to the scientific elite ■ not nearly as much evidence as Darwin ○ Darwin was reticent to publish ■ lacking some evidence ■ theory will encounter resistance, has more to lose ○ Darwin and Wallace publish together, Wallace receives some credit ● hypothesis: fueled by observation ● theory ○ can be limited in scope or very broad ○ in science, generally denotes something that is well known with no clear refutations ○ examples: gravity, evolution, big bang, germ ● law: literally no known scientific exceptions or refutations ○ laws of physics, gas laws ○ no true laws in biology ● immense amount of evidence (more than gravity) 1/27 ● sexual reproduction can shuffle existing alleles into new combinations ● in organisms that reproduce sexually, recombination of alleles is more important than mutation in producing the genetic differences that make adaptation possible ● a population is a localized group of individuals capable of interbreeding and produce fertile offspring ● if there are two or more alleles for a locus diploid individuals may be either homozygous or heterozygous ● the frequency of an allele in a population can be calculated ● by convention if there are two alleles at a locus, p and q are used to represent their frequencies ● the frequency of all alleles in a population will add up to 1 ○ p + q = 1 ● Ex: ○ 320 red (CrCr) ○ 160 pink (CrCw) ○ 20 whites (CwCw) ● calculate the number of copies ○ p = freq Cr = 800 / (800 + 200) = 0.8 ○ q = freq Cw = 200 / (800+200) = 0.2 ● sum of alleles is always 1 ○ 0.8 + 0.2 = 1 ● HardyWeinberg Equation describes the genetic makeup we expect for a population that is not evolving at a particular locus ● in a population where gametes contribute to the next gen. randomly and Mendelian inheritance occurs allele and genotype freq. … (slide before fig. 23.7) ● Hardy weinberg equilibrium (genotype freq.) p^2 + 2pq +q^2 = 1 ● genotype frequencies = Hardyweinberg equilibrium (on the test: ALLELE freq. or GENOTYPE freq. READ THE QUESTION) ● 5 conditions for nonevolving populations are rarely met in nature ○ no mutations ○ random mating ○ no natural selection ○ extremely large population size ○ no gene flow ● natural populations can evolve at some loci but not at others ● we can assume the locus that causes PKU is in Hardyweinberg equilibrium given that ○ PKU gene mutation rate is low ○ mate selection is random with respect to whether or not an individual is a carrier for the PKU allele ○ natural selection can only act on rare homozygous individuals who do not follow dietary restrictions ○ the population is large ○ migration has no effect as many other populations have similar allele freq. ● occur. of PKU is 1 per 10,000 births ○ q^2 = 0.0001 ○ q = 0.01 ● the freq. of normal alleles is ○ p =1 q = 1 0.01 = 0.99 ● the freq of carriers is ○ 2pq = 2 x 0.99 x 0.01 = 0.0198 ○ or approx. 2% of the US population ● 3 major factors alter allele frequencies and bring about most evolutionary change ○ natural selection ○ genetic drift ○ gene flow ● adaptive evolution (organisms adapting to their environment) is caused by natural selection ● the smaller sample, the greater the chance of random deviation from a predictive result ● genetic drift affects small populations ● the founder effect occurs when a few individuals become isolated from a larger population ● allele freq. in the small founder population can be different from those in the larger parent population ● the bottleneck effect is a sudden reduction … (slide before fig. 23.1013) ● understanding the bottleneck effect can increase understanding… (slide after fig. 23.10 13) ● effects of genetic drift ○ significant in small populations ○ cause allele freq. to change at random ○ can lead to a loss of genetic variation within population ○ can cause harmful alleles to become fixed ● gene flow consists of alleles among pop. ● alleles can be transferred through the movement of fertile individuals or gametes ● gene flow tends to reduce variation among pop. over time ● gene flow can decrease the fitness of a pop. ● ex: great tits (Parus major) on the Dutch island of Vlieland ○ mating causes gene flow between central and eastern pop. ○ immigration from the mainland ● important in evolutionary change in modern human pop. ○ we are more mixed than we ever have been ● natural selection is the only mechanism that consistently (ON THE TEST) ● struggle for existence and survival of the fittest are misleading ● reproductive success is generally more subtle and depends on many factors 2/1 ● speciation: the origin of new species. the part of evolutionary theory must explain how new species originate and how populations evolve to form new species ● Species and species concepts: ○ very tricky issue in biology ■ thousands of papers published ○ functionally, different among taxa ○ theoretically, many species concepts emerge ● reproductive isolation is the existence of biological factors (barriers) that impede ● prezygotic barriers are anything that prevents making a fertile zygote ● habitat isolation: two species encounter each other rarely or not at all because they occupy different habitats even though not isolated by physical barriers ● temporal isolation: species that breed at different times of the day, different seasons, or different years cannot mix their gametes ● behavioral isolation: courtship rituals and other behaviors unique to a species are effective barriers to mating ● mechanical isolation: morphological differences can prevent successful completion of mating ● gametic isolation: sperm of one species may not be able to fertilize eggs of another species ● problems with ESC: doesn't give you criteria; untestable ● phylogenetic species concept: ● allopatric/sympatric speciation ● allopatric: gets separated ● sympatric: together 2/ 3 ● Sympatric speciation takes place in geographically overlapping populations ● Sympatric speciation can occur if gene flow is reduced by factors including ○ Polyploidy ○ Sexual selection ○ Habitat differentiation ● Polyploidy is the presence of extra sets of chromosomes due to accidents during cell division ● Much more common in plants than animals ● Can produce new biological species ● Autopolyploid ● Allopolyploid ● 5 new plant species since 1850 ○ Oats, cotton, potatoes ● Gray treefrogs sympatric speciation(s.s.) chromosome based ○ Offspring can no longer reproduce with parent species ○ If sufficient numbers exist can form a self sustaining population ● Sexual selection can drive s.s. ● A hybrid zone can occur in a single band ● Hybrids have reduced fitness compared to parent species ● 3 possible outcomes of closely related species come back together in a hybrid zone ○ Reinforcement ○ Fusion ○ Stability ● A female is more likely to choose the other species of the two species are allopatric than if the species are sympatric ● Speciation can occur rapidly or slowly ● Patterns in fossil record ○ Niles Eldredge and Stephen Jay Goulds ● Punctuated pattern and evidence from lab studies suggest that speciation can occur rapidly ● 4,000 to 40 million years for speciation to occur ● How many genes change ● Ch 25 the history of life on earth ○ Past organisms were very different from those now alive ○ The fossil record shows macroevolutionary changes over large time scales ● Chem and phys processes in early earth may have produced very simple cells through a sequence of stages ○ Abiotic synthesis ○ Form macromolecules ○ Packaging molecules into a membrane (protocells) ○ B ● Earth formed 4.6 billion years ago with the rest of the solar system ● Jupiter keeps earth from getting blasted by asteroids and comets ● Pluto is a giant comet ● 1920’s Haldane and Oparin early atmosphere was reducing environment ● Rna monomers have been produced spontaneously from simple molecules ● Protocells ○ Formed from fluidfilled vesicles with a membranelike structure 2/5 ● the first genetic material was probably RNA, not DNA ● RNA molecules called ribozymes have been found to catalyze ● natural selection has produced selfreplicating RNA molecules ● RNA molecules that were more stable or replicated faster would have left the most descendant RNA molecules ● the early genetic material might have formed an “RNA world” ● vesicles containing RNA capable of replication would have been protocells ● RNA could have provided the template for DNA, a more stable genetic material ● The fossil record reveals changes in the history of life on Earth ● Sedimentary rocks are deposited into layers called strata ● few individuals have fossilized and even fewer have been discovered ● the fossil record is biased in favor of species that: ○ existed for a long time ○ were abundant and widespread ○ had hard parts ○ died in places with low oxygen levels ● radiometric dating ○ c14 → c13 → c12 ● geologic record ● 1st single celled organisms; stromatolites ● most O i2 of biological origin ● O produced by oxygenic photosynthesis reacted with dissolved iron and precipitated out 2 to form banded iron formations ● oldest fossils date back 1.8 billion years 2/8 ● the evolution of eukaryotic cells allowed for a greater range of unicellular forms ● a second wave of diversification occurred when multicellularity evolved and gave rise to algae, plants, fungi, and animals ● the oldest fossils of algae (etc…) are about 1.2 billion years old ● older fossils dating to 1.8 billion years may also be small, multicellular eukaryotes ● cambrian explosion refers to the sudden appearance of fossils that resemble modern animal phyla in the cambrian period ● human lineage of tetrapods evolved around 67 million years ago and modern humans originated only 195,000 years ago ● there are a lot of extinct lineages ● according to the theory of plate tectonics, Earth’s crust is composed of plates floating on the mantle ● tectonic plates move slowly through the process of continental drift ● oceanic and continental plates collide, separate, or slide past each other ● interactions between the plates cause the formation of mountains and islands and earthquakes ● Formation of the supercontinent Pangea about 250 million years ago had many effects ○ a deepening of ocean basins ○ reduction in shallow water habitat ○ a colder and drier climate inland ● continental drift has many effects on living organisms ○ a continents climate can change as it moves north of south ○ separation of land masses can lead to allopatric speciation ● the distribution of fossils and living groups reflects the historic movement of continents ● most species that have ever lived are now extinct ● extinction can be caused by changes to a species’ environment ● at times, the rate of extinction has increased dramatically and caused a mass extinction ● the big 5 ● 6th mass extinction caused by humans? ● 100 million years to recover from a mass extinction ● adaptive radiation is the rapid evolution of diversely adapted species from a common ancestor ● adaptive radiations may follow ○ mass extinction ○ evolution of novel characteristics ○ colonization of new regions ● extinction of dinosaurs paved the way for mammals ● adaptive radiations can occur when organisms colonize new environments with little competition ● hawaiian islands ● studying genetic mechanisms of change can provide insight into largescale evolutionary change ● EXAM 1: MONDAY 15 FEB 16 ● study ch 2226 ● mock exam up on wednesday 20 questions ● 50 questions; 50 mins; go with your first instinct 2/10 ● changes in spatial pattern ● homeotic genes determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged ● substantial evolutionary change can also result from alterations in genes that control the placement and organization of body parts ● hox genes are a class of homeotic genes ● evolution is not goal oriented more like tinkering ● CH 26 ● phylogeny is an evolutionary history of a species or a group of species ● the discipline of systematics classifies organisms and determines their evolutionary relationships ● taxonomy is the scientific discipline concerned with classifying and naming organisms ● Binomial Nomenclature ● The twopart scientific name of a species is called a binomial ● The first part of the name is the genus ● The second part, called the specific epithet, is unique for each species within the genus ● The first letter of the genus is capitalized, and the entire species name is italicized ● Both parts together name the species (not the specific epithet alone) ● domain, kingdom, phylum, class, order, family ● the evolutionary history of a group of organisms can be represented in a branching phylogeny tree ● branch point represents the divergence of two species ● sister taxa are groups that share an immediate common ancestor ● humans have no sister taxon ● phylogenetic trees show patterns of descent, not phenotypic similarity 2/12 ● monophyletic group (clade) ● paraphyletic group (same common ancestor, not all species) ● polyphyletic (different common ancestor) ● shared ancestral character is a character that originated in an ancestor of the taxon ● shared derived character is an evolutionary novelty unique to a particular clade ● a character can be both ancestral and derived depending on the context ● outgroup is the first species on the phylogenetic tree ● parsimony fewest evolutionary events is the most likely ● likelihood genes don't evolve at the same rate ●
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