Study Emphasis Exam 1
Study Emphasis Exam 1 181
Popular in General Biology
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
Popular in Biology
This 17 page Study Guide was uploaded by powersn.np on Tuesday October 18, 2016. The Study Guide belongs to 181 at North Carolina State University taught by Dr. William Grant in Fall 2016. Since its upload, it has received 4 views. For similar materials see General Biology in Biology at North Carolina State University.
Reviews for Study Emphasis Exam 1
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/18/16
SUPPLEMENTAL STUDY EMPHASIS I, BIO 181001 Exam #1 Wednesday, September 14, 2016 Coverage:Chapter 1, Chapter 20 (pp. 399407 and pp. 410411), Chapter 21, and Chapter 22 (pp. 441453 and pp. 456457) Chapter 1. The Science of Biology Define or Identify: Biology Archaea 1 Domain of life composed on prokaryotes Natural selection occurs when individuals carrying certain alleles leave more offspring than those without the alleles; generally contain considerable amounts of Genetic variation Kingdom Protista under the domain Eukarya; consists of all the unicellular eukaryotes except yeasts (which are fungi), as well as the multicellular algae; very diverse which many scientists think should make this kingdom be divided further Kingdom Plantae under the domain Eukarya; consists of organisms that have cell walls of cellulose and obtain energy by photosynthesis Kingdom Fungi organisms have cell walls of chitin and obtain energy by secreting digestive enzymes and then absorbing the products they release from the external environment. Kingdom Animalia under the domain Eukarya; contains organisms that lack cell walls and obtain energy by first ingesting other organisms and then digesting them internally. Describe the characteristics of living organisms o Cellular organization All organisms consist of one or more cells. Often too tiny to see, cells carry out the basic activities of living. Each cell is bounded by a membrane that separates it from its surroundings. o Ordered complexity All living things are both complex and highly ordered. Your body is composed of many different kinds of cells, each containing many complex molecular structures. Many nonliving things may also be complex, but they do not exhibit this degree of ordered complexity. o Sensitivity All organisms respond to stimuli. Plants grow toward a source of light, and the pupils of your eyes dilate when you walk into a dark room. o Growth, development, and reproduction All organisms are capable of growing and reproducing, and they all possess hereditary molecules that are passed to their offspring, ensuring that the offspring are of the same species. o Energy utilization All organisms take in energy and use it to perform many kinds of work. Every muscle in your body is powered with energy you obtain from your diet. o Homeostasis All organisms maintain relatively constant internal conditions that are different from their environment, a process called homeostasis. EX: body temperature remains stable despite changes in outside temperatures. o Evolutionary adaptation All organisms interact with other organisms and the nonliving environment in ways that influence their survival, and as a consequence, organisms evolve adaptations to their environments. Three Domains of Life o Eukarya (4 kingdoms: Plantae, Fungi, Animalia, Protista), Archaea, Bacteria The domains Bacteria and Archaea are composed of singlecelled organisms (prokaryotes) with little internal structure The domain Eukarya is made up of organisms (eukaryotes) composed of a complex, organized cell or multiple complex cells All animals and plants, as well as most fungi and algae, are multicellular— composed of more than one cell. Describe/discuss the levels of biological organization. CELLULAR LEVEL 1. Atoms the fundamental elements of matter are joined together by molecules 2. Molecules complex biological molecules are assembled into tiny structures called organelles with memberbounded units making up cells 3. Cells the basic unit of life; many independent organisms are composed only of single cells (EX: Bacteria) ORGANISMAL LEVEL 4. Tissues groups of similar cells ath act as a functional unit 5. Organs body structures composed of several different tissues that act as a structural and functional unity (EX: Brain: composed of nerve cells and a variety of associated tissues that form protective covering and contribute blood) 6. Organ systems organs are grouped into organ systems (EX: the nervous system consists of sensory organs, the brain and spinal cord, and neurons that convey signals 7. POPULATION LEVEL 8. Organism 9. Population group of organisms of the same species living in the same place; all populations of a particular kind of organisms together form a species, its members similar in appearance and able to interbreed 10.Community all populations of different species living together in one place 11.Ecosystem populations of organisms interact with each other and their physical environment (EX: mountain meadow interacts with the soil, water, and atmosphere of a mountain ecosystem) 12.Biosphere the entire planet can be thought of as an ecosystem List and discuss steps of the scientific method. 1. Observation see something of interest and ask a question about it 2. Hypothesis formation a possible explanation for an observation; must be tested to confirm its validity; allows for predictions to be made; iterative (a lot of repetition) they are change and refined with new data 3. Prediction If it’s true then ___ should take place; prove a way to validate the hypothesis 4. Experimentation design experiments to test that hypothesis and validate your prediction or make new ones; often includes a control group where the variable is left unaltered 5. Conclusion when you have confidence in your hypothesis based on your experiemnt process you create a theory; Discuss Darwin’s observations and conclusions that were important in development of the theory of evolution by natural selection. Scientific theory is a body of interconnected concepts o Is supported by much experimental evidence and scientific reasoning (expresses ideas of which we are most certain) o Compared to general mean of theory which implies lack of knowledge or guess Darwin and Evolution example of how a scientist develops a hypothesis and a theory gains acceptance o Darwin’s observation: characteristics of similar species varied from place to place o Hypothesis Individuals possessing physical, behavioral, or other attributes that give them an advantage in their environment are more likely to reproduce and survive than those with less advantageous traits “Descent with modification” or natural selection as mechanism for evolution o Prediction Darwin predicted that the fossil record would yield intermediate links between the great groups of organisms (Ex: between reptiles and birds); Predicted that the age of the earth must be very old because he thought the evolution of all living things from one single ancestor would have a great deal more time than what other scientists of his time were suggesting; Darwin predicted some time of inheritance (passing on favorable traits) o Experimentation Fossil Record, Mechanism for heredity (Mendel’s Laws), Comparative anatomy (homologous v analogous structures), Moleuclar evidence (Genome sequencing, Phylogenetic Trees), Earth’s real age o Conclusion Natural Selection is a mechanism for Evolution Describe the relationship between variation and success in the process of natural selection. Give examples to illustrate your response (from class). Sickle Cell trait in areas where malaria is common those with the trait are able to survive longer because sickle cells are are attacked first….. Giraffe neck giraffes with longer necks are able to reach food better and therefore survive longer, passing on the genes for longer necks to their offspring…. Moth industrial Evolution pollution darkened the trees and therefore the melanic moths were able to camouflage themselves better than the light peppered moth and thus able to survive longer…. Fish that have slightly different shaped mouths might be able to feed from parts of a coral reef that other fish are not able to access and therefore are able to survive longer passing on the more favorable trait of the shape of mouth so that the offspring are able to feed more successfully than others List and describe several types of evidence that support the theory of evolution. Fossil Record o Transitional forms have been found at predicted positions in time Earth’s age 4.5 billion years old vs. Darwin’s time when physicists were predicting earth to be only several thousands of years old o Stratification fossils are found in layers of sedimentary rock The age of the layer is directly related to the age of the fossil found in that layer Shows that life is 3.5 billion years old o For vertebrate animals especially, the fossil record is rich and exhibits a graded series of changes in form, with the evolutionary sequence visible for all to see. Mechanism for Hereditary o Mendel’s laws of inheritance were unknown to Darwin but once scientists understood them questions of his theory vanished Showed how favorable traits were passed on Comparative Anatomy evidence of origin from common ancestor o Homologous same evolutionary origin but now differ in structure and function Vertebrate forelimbs all share the same basic array of bones (human, cat, bat, porpoise, horse) o Analogous structures of different origin used for the same purpose/function (butterfly and bird wings) Molecular Evidence o Compare genomes or proteins of different organisms We are able to specify degree of relationships between various groups Ex: humans and rhesus monkeys have fewer differences in the number of amino acids in our hemoglobin than humans do with dogs, birds and frogs suggesting that we are more closely related to the Rhesus Monkey Phylogenetic trees based on tracing origin of particular nucleotide changes to reconstruct an evolutionary history Compare the following paired terms: 1. Prokaryotes and Eukaryotes Prokaryotes simplest organisms o Lack a membrane bound nucleus DNA is present in the nucleoid o Cell wall outside of plasma membrane o Do contain ribosomes (non membranebound organelles) o 2/3 domains are prokaryotes archaea and bacteria Eukaryotes more complex than prokaryotic cells o Possess a membranebound nucleus which encloses the DNA/genetic material o Hallmark is compartmentalization Achieved through use of membranebound organelles and endomembrane system o Possess a cytoskeleton for support and to maintain cellular structure a. Genomes and Proteomes Genome entire set of DNA instructions Proteomes all of proteins that the organism is capable of producing a. Artificial Selection and Natural Selection o Artificial selection a breeder selects for the desired characteristics o Natural selection environmental conditions determine which individuals in a population produce the most offspring o Both are important to evolution Student’s Questions Write at least three (3) additional questions that you believe should be included for Chapter 1. o Define emergent properties novel properties arising from the way in which components interact; often cannot be deduced solely from knowledge of the individual components o Deductive vs. inductive reasoning Deductive reasoning: applies general principles to predict specific results (Ex: mammal → hair) Inductive reasoning: uses specific observations to develop generalization that can be tested (Ex: types of dog hair) Reductionism to understand a complex system by reducing it to its working parts Thomas Malthus’s An Essay on the Principle of Population and Darwin Populations of plants and animals increase geometrically Human can only increase their food supply arithmetically Populations of species remain constant because death limits populations numbers Darwin saw that although every organism has the potential to produce more offspring than can survive, only a limited number actually do survive and produce further offspring; individuals possessing physical, behavioral, or other attributes that give them an advantage in their environment are more likely to reproduce and survive than those with less advantageous traits Unifying Themes of Biology Cell Theory All organisms are composed of cells, cells are life/s basic units, all cells come from preexisting cells Molecular basis of inheritance the information that specifies what a cell is like is encoded in deoxyribonucleic acid (DNA), a long, cablelike molecule. Each DNA molecule is formed from two long chains of building blocks, called nucleotides, wound around each other; Four different nucleotides are found in DNA, and the sequence in which they occur encodes the cell’s information. Specific sequences of several hundred to many thousand nucleotides make up a gene, a discrete unit of information.The continuity of life from one generation to the next—heredity—depends on the faithful copying of a cell’s DNA into daughter cells. The entire set of DNA instructions that specifies a cell is called its genome. The sequence of the human genome, 3 billion nucleotides long, was decoded in rough draft form in 2001, a triumph of scientific investigation. The relationship between structure and function Study structure to learn function Know a function and look for that structure in other organisms EX: receptor on human cell for insulin is found on a similar molecule in a worm and thus we might conclude this molecule functions the same in the worm as it does in humans Diversity of life arises by evolutionary change The underlying unity of biochemistry and genetics argues that all life has evolved from the same origin event. The diversity of life arises by evolutionary change leading to the present biodiversity we see 3 domains Evolutionary conservation explains the unity of living systems Biologists agree that all organisms alive today have descended from some simple cellular creature that arose about 3.5 bya. Some of the characteristics of that earliest organism have been preserved. The storage of hereditary information in DNA, for example, is common to all living things. Cells are information processing systems Information in DNA is used to direction cellular components (gene expression leads to activation or deactivation of traits) Cells process environment information and can coordinate with each other (how we maintain our internal constant temperature) Living systems exist in a nonequilibrium state Living systems are open systems which requires a constant supply of energy needed Selforganizing property at different levels (macromolecules combine, flocks of birds) Emergent properties from collections of molecules, cell and individuals The kinds of feedback and feed forward loops that exist between molecules in cells, or neurons in a nervous system, lead to emergent behaviors like human consciousness if we were to look at neurons by themselves we would not deduce consciousness by itself Chapter 20. Genes within Populations (pp. 399407 and pp. 410411 on Heterozygote Advantage) Objectives: Define evolution and population genetics o Evolution how an entity changes through time; can result from any process that causes a change in the genetic composition of a population “Descent with modification” Darwin’s definition of evolution from his book On the Origin of Species o Population genetics the study of the property of genes in a population SNPs (Single Nucleotide Polymorphisms) one of the most useful tools for analyzing populationlevel genetic variation; singlebased differences between individuals that exist in the population are more than 1%. Compare evolution by natural selection and the inheritance of acquired characteristics o In Darwin’s theory, variation is not created by experience (inheritance of acquired characteristics), but is the result of preexisting genetic differences among individuals. Natural Selection explores a mode of evolution that produces evolutionary change when some individuals in a population possess certain inherited characteristics and then produce more surviving offspring than individuals lacking these characteristics Define evolutionary fitness o a phenotype with greater fitness increases frequency; may consist of many components (a combination of survival, mating success, and number of offspring per mating) Define or Identify: Genetic variation differences in alleles of genes found within individuals in a population (natural populations contain much variation/ some regions of the genome are more variable than others); provides the raw material on which natural selection can act thereby leading to evolution; EX: human blood groups o Blending inheritance was the original thought before genetic variation; offspring were expected to be phenotypically intermediate relative to their parents; EX: height Population Any group of individuals, usually of a single species, occupying a given area at the same time. HardyWeinberg Principle predicts genotype frequencies; the primary utility of this method is to determine whether some evolutionary process or processes are operating in a population, and if so, to suggest hypotheses about what they may be; can be written as an equation p+2pg+q= 1; the original proportions of the genotypes in a population will remain constant from generation to generation, as long as the following assumptions are met: o No mutation takes place o No genes are transferred to or from other sources (no immigration or emigration takes place) o Mating is random (individuals do not choose mates based on their phenotype or genotype; EX: selffertilization) o The population size is large o No selection occurs What makes populations vary from HardyWeinberg equilibrium? Natural selection might favor homozygotes over heterozygotes Individuals may choose to mate with genetically similar individuals Influx of individuals from other populations Mutation occurring Natural Selection (a mechanism of evolution) produces evolutionary change when some individuals in a population possess certain inherited characteristics and then produce more surviving offspring than individuals lacking these characteristics. As a result, the population gradually comes to include more and more individuals with the advantageous characteristics. In this way, the population evolves and becomes better adapted to its local circumstances. EX: Several giraffes existed with various lengths of necks due to genetic differences. Individuals pass on their traits to the next generation and as several pass, longernecked individuals are more successful, perhaps because they can feed on taller trees, and pass the longneck trait on to their offspring. Inheritance of acquired characteristics (alternative theory of evolution) championed by biologist JeanBaptiste Lamarck; changes that individuals acquired during their lives were passed on to their offspring. EX: Giraffes with short necks tended to stretch their necks to feed on tree leaves, and this extension of the neck was passed on to subsequent generations, leading to the longnecked giraffe. Genetic drift random fluctuation in allele frequencies over time by chance; the smaller the population is the more susceptible it is to a dramatic change in allele frequencies due to genetic drift (causes fixation of an allele or loss of alleles in isolated populations) Gene the basic unit of heredity, a sequence of DNA nucleotides on a chromosome that encodes a protein, tRNA, rRNA molecule, or regulates the transcription of such a sequence Bottleneck effect one example of genetic drift that by chance a small percentage of alleles are passed on (drastic reduction in population) to the next generation causing the frequencies to not represent those of the previous generation; alleles that initially uncommon are particularly vulnerable; results in loss of genetic variability. EX: Northern Elephant Seal hunted to near extinction in 19th century, species lost almost all of its genetic variability and now numbers are in tens of thousands Gene pool all of the alleles for every gene in a given population Founder effect the effect by which rare alleles and combinations of alleles may be enhanced in new populations Allele one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome Evolutionary Fitness a phenotype with greater fitness increases frequency; may consist of many components (a combination of survival, mating success, and number of offspring per mating) Allele/Gene Frequency the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. Specifically, it is the fraction of all chromosomes in the population that carry that allele. Mutation the changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of a single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes Gene flow the movement of alleles into or out of a population Heterozygote Advantage a case in which heterozygotes are favored over homozygotes; works to maintain both alleles in the population o EX: sickle cell anemia Hereditary disease affecting hemoglobin Causes severe anemia Heterozygotes for sickle cell allele are much less susceptible to malaria and therefore why allele is not eliminated \ Homozygotes for sickle cell allele usually die before reproducing (without medical treatment) Compare the following paired terms: 1. Founder Effect and Bottleneck Effect: SIMILARITIES: Both have similar effects in reducing the amount of genetic diversity in a population; both events occur at random vs. natural selection where the genes with the best survival qualities are the ones that get passed on to the next generation; with genetic drift the genes that get passed on are not necessarily any better than the ones that got eliminated (favored by chance) DIFFERENCES: the type of event that caused them to occur; Bottleneck occurs when most of the population is somehow eliminated vs. Founder’s when a small group of individuals is separated and forms a new population 2. Phenotype and Genotype o Phenotype The realized expression of the genotype; the physical appearance or functional expression of a trait. o Genotype The genetic constitution underlying a single trait or set of traits. 3. Artificial Selection and Natural Selection o Artificial selection a breeder selects for the desired characteristics o Natural selection environmental conditions determine which individuals in a population produce the most offspring 4. Vertical Evolution and Horizontal Gene Transfer (2 mechanisms of evolutionary change) o Vertical evolution progression of changes in a lineage; new species evolve from preexisting species by the accumulation of mutations; natural selection takes advantage of beneficial mutations o Tree of life o Horizontal gene transfer genetic exchange between different species; genes that confer antibiotic resistance are sometimes transferred between different bacteria species o Web of life incorporates both vertical evolution and horizontal gene transfer List and discuss five major agents of evolutionary change. 1. Mutation the ultimate source of genetic variation; occurs at a slow rate so have little effect on the HardyWeinberg proportions of common alleles (ie. other evolutionary processes are usually more important in determining how allele frequencies change); mutations do NOT occur more frequently in situations in which they would be favored by natural selection 2. Gene Flow the movement of alleles from one population to another; powerful agent of change; various ways: animal physically moves into new population, drifting of gametes or immature stages into an area, or mating of individuals from adjacent populations; changes allele frequencies from generation to generation (thus making populations not in Hardy Weinberg equilibrium) only when allele frequencies for both populations reach 0.5 will both populations be in equilibrium (tends to homogenize allele frequencies among populations) 3. Nonrandom Mating individuals with certain genotypes sometimes mate with one another more commonly than would be expected on a random basis 1. Assortative Mating a type of nonrandom mating in which phenotypically similar individuals mate more frequently; does not change the frequency of the individual alleles because it does not change the reproductive success of individuals, but rather changes with whom they mate; because phenotypically similar individuals are likely to be genetically similar and thus are also more likely to produce offspring with two copies of the same allele, assortative mating will increase the proportion of homozygotes in the next generation while also decreasing heterozygotes. 2. Disassortative mating a type of nonrandom mating in which phenotypically different individuals mate more frequently; produces an excess of heterozygotes 4. Genetic Drift random fluctuation in allele frequencies over time by chance;the smaller the population is the more susceptible it is to a dramatic change in allele frequencies due to genetic drift (causes fixation of an allele or loss of alleles in isolated populations); causes big losses in genetic variation for small population. Bottleneck Effect one example of genetic drift that by chance a small percentage of alleles are passed on (drastic reduction in population) to the next generation causing the frequencies to not represent those of the previous generation. Loss of genetic variability EX: Northern Elephant Seal Founder Effect the effect by which rare alleles and combinations of alleles may be enhanced in new populations; EX: Amish populations and Ellisvan Creveld syndrome 5. Selection The process by which some organisms leave more offspring than competing ones, and their genetic traits tend to appear in greater proportions among members of succeeding generations than the traits of those individuals that leave fewer offspring; some individuals leave behind more progeny than others, and the rate at which they do so is affected by phenotype and behavior (artificial vs. natural selection); o 3 conditions for natural selection to occur and to result in evolutionary change Variation must exist among individuals in a population If no variation exists, natural selection cannot operate Variation among individuals must result in differences in the number of offspring surviving the next generation Because of their phenotype or behavior, some individuals are more successful than others in producing offspring; although many traits are phenotypically variable, individuals exhibiting variation do not always differ in survival and reproductive success Variation must be genetically inherited For natural selection to result in evolutionary change, the selected differences must have a genetic basis Compare the list of assumptions for HardyWeinberg equilibrium with the list of five major agents of evolutionary change that you identified in the previous question. 1. Mutation 1.No mutation takes place 2. Gene Flow 2.No genes are transferred to or from other sources (no immigration or emigration takes place) 3. Nonrandom 3. Mating is random (individuals do not choose mates based on their mating phenotype or genotype; EX: selffertilization) 4. Genetic Drift 4. The population size is large 5. Selection 5. No selection occurs Additional Key Resources: Review the lecture notes and powerpoints described in lecture. Study Chapter Review, p. 415. (Sections 20.1 through 20.4 and the portion of Section 20.5 on heterozygote advantage) Review Questions at the end of the chapter. Student’s Questions Write at least three (3) additional questions that you believe should be included for Chapter 20. Define and describe the differences between assortative mating and disassortative mating. o Assortative Mating a type of nonrandom mating in which phenotypically similar individuals mate more frequently; does not change the frequency of the individual alleles because it does not change the reproductive success of individuals, but rather changes with whom they mate; because phenotypically similar individuals are likely to be genetically similar and thus are also more likely to produce offspring with two copies of the same allele, assortative mating will increase the proportion of homozygotes in the next generation while also decreasing heterozygotes. Changes genotype frequencies but does not change allele frequencies o Disassortative mating a type of nonrandom mating in which phenotypically different individuals mate more frequently; produces an excess of heterozygotes o Nonrandom mating individuals with certain genotypes sometimes mate with one another more commonly than would be expected on a random basis Natural selection vs. evolution o Natural selection is a process, whereas evolution is the historical record, or outcome, of change through time; natural selection (the process) can lead to evolution (the outcome), but natural selection is only one of several processes that can result in evolutionary change; moreover, natural selection can occur without producing evolutionary change, only if variation is genetically based will natural selection lead to evolution o Result of evolution driven by natural selection is that populations become better adapted to their environment What 3 conditions have to be met for evolution by natural selection to occur? 1. Phenotypic variation must exist in the population 2. This variation must lead to differences among individuals in lifetime reproductive success 3. Phenotypic variation among individuals must be genetically transmissible to the next generation Chapter 21. The Evidence for Evolution Define or Identify: Artificial Selection change in the genetic structure of a populations due to selective breeding by humans; cattle, pigs, corn and strawberries are different from their wild ancestors because of the generations of human selection for desirable traits such as greater milk production and larger ear size; dog breeding is another example in which we great selection for maximal running ability and therefore we have our greyhound dogs (started from domesticating wolves); it has produced major evolutionary changes Homologous Structures structures with different appearances and functions that all derived from the same body part in a common ancestor Vestigial structures A morphological feature that has no apparent current function and is thought to be an evolutionary relic Convergent evolution the independent development of similar structures in organisms that are not directly related; often found in organisms living in similar environments Explain how climatic variation drives evolutionary change in the medium ground finch (Geospiza fortis). Peter and Rosemary Grant of Princeton University have studied the medium ground finch on the Galapagos Islands since 1973 The Ground Finch feeds on small, tender seeds which are produced in abundance by plants in wet years but resort to larger, drier seeds (which are harder to crush) only when small seeds become depleted during long periods of dry weather Grants found that the beak depth varied a great deal from one ear to the next in a predictable fashion o During droughts the large seeds were the majority of food available which resulted in birds with shorter and deeper beaks to survived better because those types of beaks were more powerful to break up the larger seeds; the next generation would have blunter beaks o When normal rain returns and small seeds are back in abundance, average beak depth and length of the population returned to their original size o During wet years, smaller seeds were in abundance as a result the birds with the long shallow beaks were favored and their beaks of the following generation became pointier Explain the relationship between pollution and color evolution in peppered moths (Biston betularia). Peppered forms of moths were more visible to predators on sooty trees because of their lack of camouflage the soot provided the black forms of moths Industrial melanism phrase used to describe the evolutionary process in which initially light colored organisms become dark as a result of natural selection o In this example, pollution promoted industrial melanism When Clean Air Acts were pasts in the US the frequency of melanic moths significantly reduced because their previous camouflage no longer existed and therefore peppered moths were able to survive at higher rates Discuss the value of fossils in the study of evolution. Fossils are the most direct evidence for evolution; are the preserved remains of onceliving organisms When fossils are arrayed according to their ages, from oldest to youngest, they often provide evidence of successive evolutionary change o They also document the origin of new species/periods of life o Show biological diversity through time such as the periodic mass extinctions that have reduced the number of living species Explain the importance of the discovery of transitional fossils. There are gaps in the fossil record because the low likelihood of fossil preservation and recovery → therefore we have intermediate forms, the oldest known fossil being a bird, Archaeopteryx o Clearly intermediate between bird and dinosaur possessing some ancestral traits and some traits of present day birds o Other examples include fourlegged aquatic mammal (important link in the evolution of whales and dolphins from landdwelling, hoofed ancestors), oysters, fossil snake with legs Transitional fossils shows that traits evolve at different rates and different times; expecting an intermediate form to be intermediate in every trait would be incorrect Evolutionary change is not constant for uniform Rates of evolution are varied widely with long periods of little observable change and come periods of great change Describe/discuss the evolutionary trends revealed by study of horse evolution. First horse Hyracotherium o Small with short legs, forest habitats Modern horse o Large, toe reduction and added hoof, changes in tooth size and shape, grassland habitats Adaptations to climate change o Grasslands became more widespread and contained food with more grit and hard substances Rates of evolution have varied widely; diversity was much great in the past than it is today Describe how anatomical evidence and embryonic development can be important in the study of evolution. Homologous structures structures with different appearances and functions that all derived from the same body part in a common ancestor o Different functions, same ancestor structure o Ex: the bones in the forelimb of mammals Early embryonic development o strongest anatomical evidence supporting evolution comes from comparisons of how organism develop o Ex: embryos of different types of vertebrates are often similar early on but become more different as they develop Early vertebrate embryos possess pharyngeal pouches that develop into In humans: glands and ducts In fish: gill slits Structure imperfectly used natural selection uses whatever material ias available to make future generations better o Giraffes only have 7 neck vertebrae vs other animals that have triple because mammals don’t have a wide variety available o Our eye has photoreceptors have to have to go backward to go forwards and transmit information to our brains about what we are seeing vs. other animals have a straight shot of information Vestigial structures can explain as holdovers from the past o A morphological feature that has no apparent current function and is thought to be an evolutionary relic Ex: humans possess a complete set of muscles for wiggling their ears which other mammals use to move their ears to pinpoint sounds such as the movements or growl of a predator Ex: humans appendix Pseudogenes fossil genes hemoglobin gene in the icefish Discuss how the study of biogeography is pertinent to the study of evolution. The study of the geographic distribution of species, reveals that different geographical areas sometimes exhibit groups of plants and animals of strikingly similar appearance, even though the organisms may only be distantly related Convergent evolution the independent development of similar structures in organisms that are not directly related; often found in organisms living in similar environments; natural selection appears to have favored parallel evolutionary adaptations in similar environments; because selection in these instances has tended to favor changes that made the two groups more alike, their phenotypes have converged o Marsupials and placentals Young are born immature and held in a pouch until they are ready to emerge vs placentals where offspring are not born until they are safely survive in the external environment Australian marsupials resemble placental mammals on other continents First mammals arose ~200 mya when australia was still connected to other continents Placental mammals arose much later, after continental drift had separated australia from other continents Australia has no large, terrestrial placental mammals Anteaters; nocturnal mice o Fastmoving marine predators Hydrodynamics of moving through water require a streamlined body shape to minimize friction Sharks, tuna, dolphins Plate tectonics helps show where organism's ancestors may have come into contact with each other Additional Key Resources: Review the lecture notes and powerpoints described in lecture. Study Chapter Review at the end of the chapter. Review Questions at the end of the chapter. Student’s Questions Write at least three (3) additional questions that you believe should be included for Chapter 21. o Relative dating (by position) v. isotopic dating (absolute dating) o The lower strata are generally older because young rocks form on top of older ones o Isotopic decay tells us how many years an organism has been around Ex: K (potassium) isotope 40 has 1.25 billion half life; it takes 1.25 billion years for the amount of K to decrease by 50% o How are traits produced by convergent evolution different from homologies? o Traits produced by convergent evolution have not evolved from a common ancestral trait, while homologies have Chapter 22, The Origin of Species. (pp. 441453 and pp. 456457) Define or Identify: Speciation how one species becomes another; 2 part process where 1) initially identical populations must diverge and 2) reproductive isolation must evolve to maintain these differences o Homogenizing Effect of gene flow erases differences o Speciation more likely in geographically isolated populations (allopatric) but can occur other ways (sympatric) via polyploidy individuals that have more than two sets of chromosomes via 1)autoploidy when all chromosomes arise from a single species but an error in cell division occurs where they cannot produce fertile offspring or when 2)allopolyploidy two species hybridize resulting in offspring have one copy of the chromosomes from each species and they are infertile (become fertile if chromosomes spontaneously doubled polyploidy) Gene Pool all the alleles present in a species Biological Species Concept Ernst Mayr (1942): the concept that defines species as groups of populations that have the potential to interbreed and that are reproductively isolated from other groups o the biological species concept says that a species is composed of populations whose members mate with each other and produce fertile offspring—or would do so if they came into contact. Conversely, populations whose members do not mate with each other or who cannot produce fertile offspring are said to be reproductively isolated and, therefore, are members of different species Reproductive Isolating Mechanisms any barrier that prevents genetic exchange between species Polyploidy Individuals that have more than two sets of chromosomes Adaptive Radiation closely related species that have recently evolved from a common ancestor and have adapted to many different parts of the environment o Occurs: In an environment with few other species and many resources Hawaiian and galapagos islands Catastrophic event leading to extinction of other species Discuss/describe: List and discuss/describe several examples of prezygotic isolating mechanisms. PREZYGOTIC ISOLATING MECHANISMS Ecological isolation Species occur in the same area, but they occupy different habitats and rarely encounter each other. o Ex: Lions and Tigers occur in same environment but have no record of overlap for over 150 years Behavioral isolation Species differ in their mating rituals. (visual signals, sensory signals particular wavelengths of sounds) o Ex:Galapagos Blue footed boobies have elaborate courtship display Temporal isolation Species reproduce in different seasons or at different times of the day. o Ex: 1 flower blooming in the spring while the other blooms in the summer Mechanical isolation Structural differences between species prevent mating. o Ex: sexual organs don’t fit Prevention of gamete fusion Gametes of one species function poorly with the gametes of another species or within the reproductive tract of another species. o Ex: those that shed gametes into the water have a low possibility that they come into contact with each other POSTZYGOTIC ISOLATING MECHANISMS Hybrid inviability or infertility Hybrid embryos do not develop properly, hybrid adults do not survive in nature, or hybrid adults are sterile or have reduced fertility. Describe the effect of mass extinctions on species diversity. Compare the following paired terms: prezygotic reproductive isolating mechanisms and postzygotic reproductive isolating mechanisms o Prezygotic Mechanisms that prevent formation of a zygote include ecological or environmental isolation, behavioral isolation, temporal isolation, mechanical isolation, and prevention of gamete fusion o Postzygotic All of the factors we have discussed so far tend to prevent hybridization. If hybrid matings do occur and zygotes are produced, many factors may still prevent those zygotes from developing into normally functioning, fertile individuals. allopatric speciation and sympatric speciation o Sympatric speciation: the differentiation of populations within a common geographic area into species; EX: birds a bird feeder Phenotypically different, utilize different parts of the habitat, behave separately One species splits into two at a single locality, without the two new species ever having been geographically separated One type occurs commonly as the result of polyploidy – Individuals that have more than two sets of chromosomes o Allopatric speciation : takes place when populations are geographically isolated Appear much more likely to have evolved substantial differences leading to speciation Student’s Questions A. Write at least three (3) additional questions that you believe should be included for Chapter 22. Natural selection may favor the evolution of increased prezygotic reproductive isolation between sympatric populations when postzygotic isolation initially exists and prezygotic isolation is only partial. This phenomenon is termed reinforcement, and it may lead to populations becoming completely reproductively isolated. In contrast, however, genetic exchange between populations may decrease genetic differences among populations, thus preventing speciation from occurring. o Selection may reinforce isolating mechanisms Formation of species a continuous process 2 populations may be only partially reproductively isolated Reinforcement initially incomplete isolating mechanisms are reinforced by natural selection until they are completely effective Which of the following situations will result in homogenization of two populations? o Interbreeding between two populations that are incompletely reproductively isolated Character displacement natural selection in each species favors those individuals that use resources not used by the other species greater fitness, trait differences in resource use will increase in frequency over time, species will diverge o Individuals in each species that are most different from the other species will be favored by natural selection, because they will not have to compete with the other species
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'