Bio 104: EXAM ONE STUDY GUIDE
Bio 104: EXAM ONE STUDY GUIDE Bio 104
Kutztown University of Pennsylvania
Popular in Principles of Biology
verified elite notetaker
Popular in Biology
This 24 page Study Guide was uploaded by Ashlee Notetaker on Monday February 8, 2016. The Study Guide belongs to Bio 104 at Kutztown University of Pennsylvania taught by Dr. Sacchi in Spring 2016. Since its upload, it has received 135 views. For similar materials see Principles of Biology in Biology at Kutztown University of Pennsylvania.
Reviews for Bio 104: EXAM ONE STUDY GUIDE
I had to miss class because of a doctors appointment and these notes were a LIFESAVER
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: 02/08/16
Biology: The scientific study of life Major Groups of Living Organisms: Bacteria – microscopic organisms with a very simple structure. Not visible to the naked eye. Protist – eukaryotic organisms that are unicellular and sometimes colonial or less often multicellular. Larger in size and more complex than bacteria. Not visible to the naked eye. Example: Paramecium Fungi – a diverse group of eukaryotic singlecelled or multinucleate organisms that live by decomposing and absorbing the organic material in which they grow. Digest food externally. Example: Morel Plants – eukaryotic and mostly multicellular, photosynthetic – food from the sun. Example: Sunflower Animals – multicellular organism that ingest their own food. Example: Cat Diversity of life may be defined by several basic characteristics that are shared by all organisms: Organisms are composed of chemical elements. Organisms obey the same laws of chemistry and physics that govern everything within the universe. The characteristics of life: Provide insight into the unique nature of life, and help distinguish living organisms from nonliving things. Life is organized: Atoms: most basic unit of matter. Molecules: atoms combine to form molecules. Cell: molecules combine to form cells, otherwise known as the basic unit of life. o Although a cell is alive, it is made from nonliving molecules. o Some cells clump together to form colonies. Example: Alga volvox o Some cells live independently. Example: singlecell Paramecium Tissues: a group of cells with a common structure and function. o Example: nervous tissue or leaf tissue Organ: composed of tissue functioning together for a specific task. o Example: brain Organ System: composed of several organs working together. o Example: nervous system Organism: an individual; complex individuals contain organ systems. o Example: Elephant Population: organisms of the same species in a particular area. o Example: bunch of elephants Community: interacting populations in a particular area. o Example: elephants and zebras together Ecosystem: a community, plus the physical environment. Biosphere: regions of the earth’s crust, waters and atmosphere inhibited by living organisms. Moving up the hierarchy = More complex Multicellular: living organisms that contain more than one cell. Emergent Properties: unique characteristics that are determined by the interactions between the individual parts. Example: when cells are broken down into bits of membrane and liquids, these parts themselves cannot carry out all the basic characteristics of life. Life Requires Materials and Energy: Without a source of energy and nutrients organisms cannot carry on life activities. o Food provides nutrients, which are used as building blocks or for energy. Energy: capacity to do work, and it takes work to maintain the organization of the cell and organism. Metabolism: when cells use nutrient molecules to make their parts and products, they carry out a sequence of chemical reactions. Thus, metabolism refers to all chemical reactions in a cell. The ultimate source of energy for nearly all life on earth is the sun. o Plants and other certain organisms are able to capture solar energy through the sun by photosynthesis. Photosynthesis: a process by which solar energy is transformed into chemical energy of organic nutrient molecules. All life on earth requires energy by metabolizing nutrient molecules made by photosynthesizes (applies to pants). Within an ecosystem – chemicals cycle and energy flows. o Example: grasses take in solar energy and inorganic nutrients to produce food (organic nutrients) by photosynthesis. o Chemical cycling occurs as chemicals move from one population to another in a food chain, until death and decomposition allow inorganic nutrients to be returned to the producers again. o Energy flows from the sun through plants and the other members of the food chain as they feed on one another. The energy (gradually) dissipates and returns to the atmosphere as heat. Without energy ecosystems could not stay in existence and photosynthetic organisms unable to absorb it. o Energy flow and nutrient cycling in an ecosystem climate largely determine not only where different ecosystems are found in the biosphere but also what communities are found in the ecosystem. Example: deserts exist in areas of minimal rain vs. forests require much rain. Maintaining Homeostasis: biological balance (for life to continue) temperature, moisture level, acidity and other physiological factors must remain within the tolerance range. Maintained by systems that monitor internal conditions and make routine and necessary adjustments. Interact feedback and control mechanisms that require any conscious activity. o The control mechanisms: one or more tissues or by the nervous system. o In animals, these behaviors are controlled by the nervous system and are usually not consciously controlled. Example: a lizard may raise its internal temperature by basking in the sun, or cool down by moving into the shade. Living organisms respond to their environment: the ability to respond often results in movement; appropriate responses help to ensure the survival of the organism. Example: plants turn toward the sun Singlecelled organisms can respond to their environment. o Example: the snapping of whip like tails moves them toward or away from light or chemicals. Multicellular organisms can manage more complex responses. o Example: a monarch butterfly can sense the approach of fall and begin its flight south while resources are still abundant. Organisms display a variety of behaviors as they maintain homeostasis and search and compete for energy, nutrients, shelter and mates. Living organisms reproduce and develop: All forms of life have the ability to reproduce, or make another organism like itself. Bacteria, protests, and other singlecelled organisms simply split into two. In most multicellular organism sexual reproduction – combination of sperm and egg. When living organisms reproduce their genes, or genetic instructions, are passed down to the next generation. o Combination of sperm and egg, each contain a unique collection of genes – ensure that the offspring has new and different characteristics. Genes are made of DNA (deoxyribonucleic acid) molecules. o DNA provides the blueprint, or instructions, for the organization and metabolism of the particular organism. Not all members of a species are exactly the same – differences are a result of mutations, or inheritable changes in the genetic information. o Mutations provide an important source of variation in the genetic information. Example: eye and hair color o Mutations help create a diversity, even within a group of identical organisms. Sometime organisms inherit characteristics that allow them to be suited to their environment. All cells in a multicellular organism contain the same set of genes, but only certain genes are turned on in each type of specialized cell, creating differences or variations (these differences are mutations). Living organisms have adaptations: adaptations are modifications that make organisms better able to function in a particular environment. Example: penguins have many behavioral adaptations to living in the artic. They slide on their bellies across the snow to conserve energy when moving quickly. Evolution: the way in which population of organisms change over the course of many generations to become more suited to their environments. Evolution and classification of life Organisms share the same basic characteristics: o Composed of cells. o Composed of DNA. o Same metabolic reactions to acquire energy and maintain their organization. The unity of life suggests that they are descended from a common ancestor – decent with modification. Charles Darwin: concluded natural selection is the process that makes modification – that is, adaption possible. Process of natural selection Environment selects which trains are more apt to be passed to the next generation. o Selective agent will either be: Biotic: part of the living environment (deer) Abiotic: part pf the physical environment (altitude) Example: deer eat smooth leaves, rather than hairy. Thus, hairy leaves reproduce more. Smooth leaves are being selected against. Natural selection selects for or against new traits introduced into the population by mutation. Over many generations forces such as competition, predation and the physical environment alter the makeup of a population – favoring those suited to the environment. Mutations fuel natural selection – because they introduce variations among members in a population. Prevention of Reproduction Inability to capture resources o Example: long neck but not short neck giraffes can reach their food sources Organisms with advantage traits can produce more offspring than those that lack them. Natural selection tends to sculpt a species to fit its environment and lifestyle and can create new species from existing ones. Organizing Diversity Evolutionary Tree: traces the ancestry of life on earth to a common ancestor. Evolution = unifying concept of biology. Because life is so diverse. . . Taxonomy: discipline of identifying and grouping organisms according to certain rules. Systematics: study of evolutionary relationships between organisms. o DNA technology used Levels of classification Domain – species placed in different domains are most distantly related. Kingdom Phylum Class Order Family Genus Species – least inclusive category – group of interbreeding individuals. Each category above species contains one more organism than the preceding one. Domains: Bacteria (may have evolved from the first common ancestor soon after life began) Archaea (may have evolved from the first common ancestor soon after life began) Eukarya Domain bacteria and archaea contain the prokaryotes, which lack the membranebound nucleus found in eukaryotes of domain eukarya. Archaea organize their DNA differently than bacteria, and their cell walls and membranes are chemically more similar to eukaryotes. Conclusion = eukarya split off from archaeal line of descent. Prokaryotes are structurally simple but metabolically complex. Archaea (“ancient”) are the least evolved forms of life. Bacteria are variously adaptive to living almost anywhere. Doman Archaea: o Prokaryotic o Various shapes o Adapt to extreme environments o Absorb or chemosynthesize food o Unique chemical characteristics Domain Bacteria: o Prokaryotic o Various shapes o Adapt to all environments o Absorb, photosynthesize or chemosynthesize food o Unique chemical characteristics Taxonomists are in the process of deciding how to categorize archaea and bacteria into kingdoms. Domain Eukarya: contain 4 major groups of organisms Protist: comprised of a number of kingdoms, range from singlecelled forms to a few multicellular forms. Some are photosynthesizes, and some must acquire their own food. Common protist: algae, the protozoans and water molds. Thus, plants, fungi and animals most likely evolved from protists. Kingdom Fungi: molds, mushrooms, yeasts and ringworms. Multicellular and complex – absorb food. Kingdom plantae: algae, mosses, ferns, coniferns and flowering plants. Multicellular and complex – photosynthetic. Kingdom Animalia: Sponges, worms, insects, fishes, birds, frogs and mammals. Multicellular and complex – ingest food. Binomial Nomenclature: Assign each living organism a twopart name called a scientific name. First word: genus (capitalize genus only) Second word: specific epithet (species) Used to avoid confusion o Common names tend to overlap Process of Science Life can be studied at a variety of levels o Cytology: study of cells o Anatomy: study of structure o Physiology: study of function o Botany: study of plants o Zoology: study of animals o Genetics: study of heredity o Ecology: study of interrelationships between organisms Scientific method: standard series of steps used in gaining new knowledge that is widely accepted among scientists. Observation: a formal way of seeing “what happens” Hypothesis: an informed statement that can be tested in a manner suited to the processes of science. Inductive reasoning: whenever a person uses creative thinking to combine facts into a cohesive whole. Predictions and experiment: serious of procedures to test a hypothesis. To determine how to test a hypothesis a scientist uses deductive reasoning – “if, then” logic. A scientist may make a prediction, or expected outcome. Experimental Design: manner in which a scientist intends to conduct an experiment. Experimental variable (independent variable): examining the contribution of a specific variable. The result = responding variable (dependent variable). Control group: not exposed to experimental variable. Test group: is exposed to the experimental variable. Scientists use model organisms and model systems to test a hypothesis. o By using a model the researcher is able to control aspects of the experiment. Example: age and genetic background Model systems allow the scientist to control specific variables and environmental conditions (may not be possible in natural environment). Presenting and analyzing the data: the data, or results, from scientific experiments can be presented in a variety of formats, including tables and graphs. Graphs: show relationships between two quantities. Experimental variable: xaxis (horizontal) Results: yaxis (vertical) Standard deviation: variation/standard error Statistical analysis: mathematical tests that allows one to test whether treatment and control groups differ from one another, or if they are too similar to conclude that the groups differ. Scientific publication: peer review Theories: concepts that join together wellsupported and related hypothesis. Example: Cell theory – all organisms are composed of cells, and new cells come from only preexisting cells. Other theories: homeostasis and evolution Principle: theories that are generally accepted by an overwhelming number of scientists (some people prefer the term law rather than principle) Example: Evolution Ulcer example of scientific method – from text Hypothesis: antibiotic B is a better treatment for ulcers than antibiotic A Experiment: three groups treated for ulcers, two groups got two different antibiotics and the third group received no antibiotic – instead, placebo. All three groups thought they were taking the same thing to avoid experimental biased. Control group: received placebo Test group one: antibiotic A Test group two: antibiotic B Collect data: each subject was examined for the presence of ulcers. Results and conclusion: 2 weeks go by and stomach/intestinal linings of each subject is observed to see if ulcers still present (done by endoscopy). Doubleblind theory: neither patience nor the techs are aware of the specific treatment. Conclusion: hypothesis supported Challenges facing science Technology: application of scientific knowledge at the interest of humans. Biodiversity: total number and relative abundance of a species, the variability of their genes, and they different ecosystems in which they live. o 15 million species (estimated) worldwide. 2 million so far named and identified. Extinction: death of a species or larger classification category. o Losing hundreds of species per day. Thus, 38% of all species may be in danger of extinction before the end of the century. Coral Reef: diverse ecosystem that is vulnerable to the impact of humans. o Tropical rainforest see a threat as well The destruction of healthy ecosystems has many effects; we depend on them for food medicine and various raw materials. Emerging Diseases: Avian Influenza SARS – severe acute respiratory syndrome West nile virus Zika virus Climate Change: changes in the normal cycle of the earth’s climate (may be attributed to human activity). Imbalance of element carbon – normally carbon is cycled and due to human activity more CO2 is being released into the atmosphere, than being removed. By the burning fossil fuels and the destruction of forests more CO2 is released. The amount released is two time the amount that remains in the atmosphere. The increased amount of carbon dioxide (along with other gases) in the atmosphere is causing a rise in temperature called global warming. o These gases allow the sun rays to pass through, but they absorb and radiate heat back to earth, a phenomenon called the greenhouse effect. The field of Taxonomy Taxonomy: the branch of systematic biology that identifies, names and organized biodiversity into related categories. Taxon: a group containing an organism or a group of organisms that exhibit a set of shared traits. Classification: the process of naming and assigning organisms to a taxon. Systematics: study of evolutionary relationships among organisms. Taxonomists: scientists who study taxonomy, strive to classify all life on earth. Aristotle (384322bce) was interested in taxonomy and sorted organisms into groups, such as horses, birds and oaks – based on a set of shared traits. Taxonomists after Aristotle focused on physical traits to classify organisms. o This was problematic – so instead, taxonomists attempt to classify organisms into natural groups (organisms that represent a shared evolutionary history). Done by: Phylogeny – evolutionary family tree. Advances in DNA technology allow modern systematic biologist to compare traits other than external features to classify organisms. o Example: phylogeny of different animals constructed from DNA sequences clearly shows that on various different animals (beetles, birds and bats) all have wings that evolved at different times in the history of life. This means they do not share a common ancestor with wings – rather, wings originated three times independently, on three different branches on the tree of life. This is a result of convergent evolution; organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments. Linnaean Taxonomy: Name: Carolus Linnaeus – creator of classification hierarchy. The father of modern taxonomy (to organize biodiversity). Developed binomial nomenclature. o Each species receives a two part Latin name (Genus, specific epithet). o Use Latin because it is a universal language – avoiding confusion. o Binomial nomenclature classifies species as follows: species, genus, family, order, class, phylum, and kingdom – most recent higher taxonomic category = domain. o Organisms that fill a particular classification category are distinguishable from other organisms because of their shared traits. Example: organisms in the same domain have general traits in common, where organisms in the same species have specific traits in common (species is the most exclusive). Binomial nomenclature does not represent any special relationship among organisms in nature. Should be views as the best working hypothesis of evolutionary relationships. DNA Barcoding: compares short fragments of DNA sequence of an unknown organism to a large data base of sequences from known organisms. Helps to determine which taxonomic group the organism likely belongs to or if it is something new to science. Criticized for being too simplistic. 3 Domain system Aristotle’s time only recognized two kingdoms: o Plantae (plant) o Animalia (animals) 1880’s, Ernest Haeckle proposed adding a third domain. o Protista (protist) – singlecelled microscopic organism 1969, R.H Whittaker expanded the system to a five kingdom system: monera, protista, fungi, plantae and Animalia. o Kingdom Monera: singlecelled bacteria – containing all prokaryotes (lack membrane bound nucleus). o Other kingdoms = eukaryotes Organisms placed in these kingdoms based on type of cell (prokaryotic vs. eukaryotic), complexity (singlecelled vs. multicellular), and type of nutrition. Defining domains: Late 1970’s Carl Woese compared the nucleotide sequences of ribosomal RNA (rRNA) among prokaryotes. o Found: prokaryotes at high temperatures or produced methane are quite different from all of the other prokaryotes and eukaryotes. o Proposed two groups of prokaryotes rather than one. o Further found that the prokaryotes were so fundamentally different from each other they should be assigned separate domains. Domain Bacteria (prokaryotic) Domain Archaea (prokaryotic) Domain Eukarya (eukaryotic) Data suggest: Bacteria and archaea evolved early in history of life from the last universal common ancestor. Later – eukarya diverged from archaea. Thus, bacteria (oldest linage) and eukarya (youngest). Domain Bacteria: Found in large numbers in nearly every environment. Archaea are structurally similar to bacteria but differ because of biochemical differences. Cyanobacteria (photosynthetic prokaryotes) belong to an ancient lineage of bacteria – may have been the first organism to contribute oxygen. Heterotrophic (use organic compounds as a source of energy and carbon). o Beneficial because they break down organic remains. Along with fungi, keep chemical cycling going, so plants always have a source of inorganic nutrients. Domain Archaea: Prokaryotic singlecelled organisms. Reproduce Asexually. Don’t look much different than bacteria from under the microscope. Live in extreme conditions (can live in environment without oxygen). Distinguishable from bacteria in the difference of rRNA nucleotide sequences and by unique plasma membrane (diverse lipids very different from bacteria) and cell wall (which help to live in harsh environments) chemistry. Domain Eukarya: Singlecelled and multicellular organism. Have membrane bound nucleus. Various organelles. o Some of which arose through endosymbiosis of other single celled organisms. Sexual reproduction common. Various types of life cycles seen. Eukarya has various kingdoms. o Fungi Eukaryotes, form spores (allow fungi to reproduce), lack flagella (whip like structure that allow cells to move), cells walls (contain chitin – protective layer), multicellular with few exceptions, saprotrophic (they secrete digestive enzymes and then absorb the nutrient from decaying organic matter). Examples: mushrooms, molds, yeast. o Plants Photosynthetic, multicellular, adapted to land environments, share a common ancestor (aquatic photosynthetic protist), land plants have true tissues and organ system level of classification. Examples: cacti, ferns and cypress trees. o Animals Motile, eukaryotes, multicellular, evolved from a heterotrophic (thus, they are heterotrophic) protist, true tissues and organ system level of classification. Examples: worms, whales and insects. Charles Darwin December 1831, at age 22 Darwin set sail aboard the British naval vessel HMSBeagle. His mission was to serve as the ships naturalist – collecting geological and biological diversity. When Darwin set sail – widely believed species had remained unchanged since the time of creation. Forged from religious beliefs, not experiment and observation of the natural world. His voyage led him to propose species arise and change. This process – evolution. Evolution proposed that genetic change occurs in species over time, which leads to their genetic and phenotype differences. o Due to natural, not super nature forces. Gradually gained credibility as result of scientific and intellectual revolution in Europe in the late 1800’s. Eighteenth and nineteenth centuries were a time of exploration and discovery. Darwin’s theory took root and grew. MidEighteenth Century Influences Beliefs of the eighteenth century (JudeoChristian teachings about creation) can be traced back to Greek philosophers Plato and Aristotle. Plato: believed every species on earth has a perfect or “essential” form – and species variation is imperfection of this essential form. Aristotle: believed organisms vary in complexity and can be arranged based on their order of increasing complexity. GeorgesLouis Leclerc (Count Buffin): Naturalist Worked most of his life writing a 44 volume natural history series that described all plants and animals. Provided evidence of evolution. o Proposed various causes such as, environmental influence and the struggle of existence. Believed special creation and fixity of species. Carolus Linnaeus: Chief of taxonomists Developed binomial nomenclature. o As well as, classification system for living organisms. Believed in the fixity of species (or that each species had an “ideal form”) Believed in the Scala naturae (“ladder”) – simplest beings occupy the lowers rungs and spiritual beings occupy the two highest (angels, humans and God). Biologist of this time used comparative anatomy – the evolution of similar structures in a variety of species, to classify organism into groups. By the late 18 century fossils were discovered and scientists knew that they were plant and animal remains from the past. Explorers who traveled the world brought back newly discovered extant (still in existence) and fossil organisms to be compared to known living species. o First scientists thought each fossil had a living descendent, wrong because eventually some fossils didn’t match well with known species. Baron Georges Cuvier: the first to suggest that some known species known only from the fossil record had become extinct. Erasmus Darwin (Charles Darwin Gdad): physician and naturalist His botany and zoology notes suggest possibility of evolution. Basing his conclusions on animals during development, animal breeding by humans (artificial selection), and the presence of vestigial structures. o Vestigial structures: anatomical structures that functioned in an ancestor but since lost most or all of their function in a descendent. Like Buffon, Erasmus Darwin thought species might evolve, but offered no mechanism by which this change might occur. Late Eighteenth Century, Early Nineteenth Century Influences Baron Georges Cuvier: a distinguished zoologist, used comparative anatomy to develop classification system. Cuvier founded paleontology; study of fossils. Studies revealed assembly of fossils changes suddenly between different layers of sediment or strata (layers of sedimentary rock) result from slow disposition of silt, volcanic ash and other materials, within a geographic region. Proposed sudden changes of fossil variation could be explained by a series of local catastrophes, or mass extinctions, followed by repopulation by species from surrounding areas – known as catastrophism. JeanBaptiste de Lamarck: st 1 biologist to propose a testable hypothesis to explain how evolution occurs via adaptation. Entirely different ideas on decent than those of Cuvier. Lamarck studied fossilized life forms in the earth’s strata. o Proposed: more complex organisms are descended from less complex organisms. Mistakenly concluded the increasing complexity is a result of a natural motivating force (a striving for perfection). To explain the process of adaptation to the environment – Lamarck proposed the idea of inheritance of acquired characteristics (the environment can produce physical change in an organism during its lifetime that are inheritable). o His example: Giraffes stretched their necks to reach their food in tall trees, the longer neck would be passed to offspring. His hypothesis of inheritance of acquired characteristics has never been supported by experimentation. o Molecular mechanism of inheritance explains why phenotypic changes acquired during an organism’s lifetime do not result in genetic changes that can be passed down. James Hutton: Proposed a theory of slow, uniformal geological change. Charles Lyell: geologist of Darwin’s time. Made Hutton’s ideas popular in book principles of geology, pub. In 1830. Hutton explained earth is subject to slow but continues cycles of rock formation and erosion. o Not shapes by sudden catastrophes. o Proposed erosion produces rock and dirt debris that is washed into rivers, transported into oceans, and deposited into thick layers, over time converted into sedimentary rock (often contain fossils that are uplifted from below sea level to form land during geological upheavals). o Lyell went to propose the theory of uniformitarianism; natural processes of today are the same as those which occurred in the past. o Hutton’s ideas still accepted – although rate of change does not stay consistent through history. Thus, the earth must be very old. Darwin’s Theory of Evolution Darwin was sent to med school at 16. Didn’t work out – went to school to become a clergyman – ended up studying bio/geo. During this time became friends with botanist John Henslow, who gave him skills on identification and collection of plants. Darwin conducted field work with Adam Sedgewick, one of the founders of modern geology (summer 1831). Darwin explored southern hemisphere after being awarded BA. o A naturalist aboard the HMS Beagle. o 2 years – ended up being 5. o Encountered many difference species. o Darwin gathered evidence that organisms are related through descent with modification from a common ancestor, and the adaption to various environments leads to diversity. o Began contemplating the origin of new species. Darwin’s Observations over Time Observed massive geological changes. o Explored raised beaches (which is now Argentina). o Many raised beaches had exposed layers of sediment that contained a variety of fossilized shells and bones of extinct mammals. o Darwin collected fossil remains of an armadillolike animal (glyptodon) as well as a giant sloth (Mylodon darwinii). o Observed marine shells in Andes Mountains – suggest to him the earth is very old. Thus, enough time for decent with modification to occur. Therefore, living organisms could be descended from extinct forms known only from the fossil record. Species not fixed, instead change over time. Biogeographical observations: Biogeography: study of geographical distribution of organisms throughout the world. Providing hints about past geological events: o Movement of continents. o Formation of volcanic islands. o Ecological change (glaciation and river formation). Compared animals of South Africa to those with which he was familiar. o South Africa vs. Europe: although different animals, similar environments on each continent had similar looking animals. Example: Rabbits (Europe) and Patagonian Cavy (South Africa). Patagonian cavy have long legs and ears with the face of a Ginny pig. Both animals ate grass, hid in bushes and moved rapidly using long hind legs. Darwin saw how similar species replaced one another – therefore, related species could be modified accords to environmental differences (northern vs. southern latitudes). Exploring the Galapagos Islands provided Darwin with more evidence. o Too far from mainland for most terrestrial animals and plants to colonize, yet life is present. o Species of plants and animals he found there varied from island to island and were different from the mainland. Example: long neck vs short neck tortoise. o Darwin’s most famous study from the Galapagos Islands were his study of finches. Darwin did not initially recognize that the birds were finches (used to what he saw in England). 13 species of finches – each have a beak adapted to a particular way of life. Darwin speculated whether the different finches could have descended from a mainland finch species (common ancestor). Perhaps new species arise because of geographical distance between the island isolated populations of birds. Long enough for them to evolve independently. Perhaps modern day species has resulted from accumulated changes occurring within each of these isolated populations. Upon Returning back in England… Darwin fully developed his idea of natural selection as a mechanism for evolutionary change in 1842. In 1858 Alfred Wallace spent an essay to Darwin proposing a similar concept. o 8 years of collecting data in the Malay Archipelago helped Wallace develop his theory. Idea of natural selection presented to the Linnean society (London) in 1858 as a pair of essays by Darwin and Wallace. Natural Selection Organisms exhibit variation that can be passed from one generation to the next (heritable). Organisms compete for available resources. Individuals within a population differ in terms of their reproductive success. Organism’s become adapted to conditions as their environment changes. Organisms have Heritable Variation Darwin emphasized that the members of a population vary in their function, physical and behavioral characteristics. o Before Darwin these were not views as important because they were not descriptive to fixed species. Suspected evidence of inheritance existence but did not have evidence we have today. Genes are unit of heredity and along with environment determine the phenotype of an organism. Random mutations have been shown to be the source of new genetic variation in a population. Genetic variation can be harmful, helpful and neutral to survival and reproduction. Genetic variation arises by chance and for no particular purpose. o Harmful variation is eliminated from population by natural selection, because individuals with such mutation often do not survive and reproduce. o Beneficial/neutral variation can be maintain in a population. Natural selection ignores neutral variation. Beneficial mutation increase = higher reproductive success. Natural Selection operates on heritable variation already present in a population gene pool, and that selection process is random with no goal of improvement. Organisms Compete for Resources If all offspring born to a population were to survive, insufficient resources would be available to support the growing population. This overproduction potential of a species is often referred to as the geometric ratio of increase. Organisms Differ in Reproductive Success Some individuals have favorable traits that enable them to better compete for limited resources. o Thus, acquire more resources than the individuals with less favorable traits and can devote more energy to reproduction. Darwin called the ability to have more offspring differential reproductive success. o Fitness: reproduce success of an individual relative to other members of a population. Most fit individuals acquire more resources and convert these resources into a larger number of viable offspring. Factors that influence fitness vary from population to population. Natural selection occurs because certain members of a population happen to have a variation that allows them to survive and reproduce to a greater extent than do other members. Organisms Become Adaptive An adaption is an evolved trait that helps an organism be more suited to its environment. Recognizable when unrelated organisms living in a particular environment display similar characteristics. Adaptation to environment result from natural selection. Differential reproduction generate after generation can cause adaptive traits to increase in frequency in each succeeding generation. Natural selection is the only process that results in environment adaptation. We can observe Selection at Work Artificial Selection: human – controlled breeding to increase the frequency of desired traits. Possible because original population exhibits a variety of characteristics, allowing humans to select traits that they prefer. Example: dog breeding and artificial selected plants Darwin described artificial selection as a model by which to understand natural selection. With natural selection however the environment – not human selection – proves the selective force. Peter and Rosemary Grant of Princeton University Began studying finches in 1973. Found that beak sixe varies from wet years to dry years (weather affects seeds). Research demonstrates evolutionary change can sometimes be observed within the timeframe of a human lifespan, rather than over thousands of years. Advantages in biotechnology have produced a set of new and revolutionary tools to document phenotype evolution at the level of a gene. New traits can evolve as a result of only a few changes in the DNA code that regulate a gene. Industrial Melanism: prevalence of darkcolored varieties of animals in industrial areas where they are better camouflaged against predators than paler forms. Example: peppered moth, resistance to antibiotics by bacteria, resistance to pesticides by insects change in viruses. Evidence of Evolution Fossil Evidence: remains and traces of past life or any other direct evidence of past life. Traces: tails, footprints, burrows, worm casts, preserved droppings When an organism dies, the soft parts are either consumed by savages or decomposed by bacteria. Occasionally the organism is buried in such a way that decomposition is never completed or is completed so slowly that the soft parts left an imprint of their structure. Most fossils consist of hard parts: not consumed or destroyed. o Shells, bone, teeth Transitional Fossils: bear a resemblance to two groups that in the very present are classified separately. Represent an intermediate evolutionary form of life in transition from one form to another. Transitional fossils allow us to retrace the evolution of organisms over relatively long period of time. Example: “fishapod” – transitional form between a fish and a four legged animal, the tetrapod. Fossils have been discovered that support the hypothesis that whales had terrestrial ancestors o Ambulocetus natans – “the walking whale that swims” o Anatomical transitions: hind limbs of tetrapod terrestrial ancestor; nasal opening from nose to the top of the head. Biogeography – diversification of marsupials in Australia, each adapted to a different way of life. All the marsupials in Australia presumably evolved from a common ancestor. Were free to diversify because few placental mammals were present in Australia. o Placental mammal: young complete their developmental inside the mother’s uterus, nourished by the placenta. Where placental mammals are abundant, marsupials are not as abundance due to competition. Placental mammals eventually were able to migrate into South America. o Result: marsupial mammals were out competed by placental mammals, and the diversity of marsupials in South America declined greatly. Biogeographical differences provides evidence that variability in a single, ancestral population can lead to adaption to different environments through the forces of natural selection. o Competition for resources appears to provide some of the pressure that leads to diversification. Anatomical Evidence: decent from a common ancestor can explain anatomical similarities among organisms. o All vertebrate forelimbs contain the same sets of bones organized in similar ways, despites their dissimilar functions. o Plausible explanation: basic forelimb plan was present in a common ancestor. This plan was modified independently in all descendants as each continued along its own evolutionary pathway. Homologous: Anatomically similar Analogous: same function but originated independently in different groups of organisms that do not share a common ancestor. Example: wings of birds and insects Vestigial Structures: anatomical features that are fully developed in one group of organisms but are reduced and may have no function in related groups. Occur because organisms inherit their anatomy from their ancestors, and therefore their anatomy carries traces of their evolutionary history. Example: bird’s wings used for flight, while some species have greatly reduced wings and do not fly. Similarly, tail bone and wisdom teeth are examples of human structures that have no apparent function in our species. The homology shared by vertebrates is observable during the embryological developments. o Sometime during development all vertebrates have: Post anal tail Paired pharyngeal (throat) pouches Notochord Biochemical Evidence: compare structure of important macromolecules. All living organisms use the same basic biochemical molecules: o DNA deoxyribonucleic acid o RNA – Ribonucleic acid o ATP – Adenosine triphosphate Organisms use a triplet nucleicacid code in their DNA to encode for one of the twenty amino acids that will form their proteins. o Universal genetic code (all organisms) The sequence of amino acids in cytochrome c (a protein essential to cellular respiration) is very similar to that of yeast. o Number of differences in the amino acid sequence in humans and other organisms increases as the distance in time since they shared a common ancestor increases. Evidence from Developmental Biology Developmental genes are shared among all animals. Life’s diversity has come about by a set of regulatory genes that control the activity of other genes involved in development. o Simple changes of how genes are controlled can have profound effects on the phenotype of organisms. Criticism of Evolution Evolution is a theory about how life originated. There are no transitional fossils. Evolution proposed that life can change as a result of random events; clearly traits are too complex to have originated by chance. Evolution is not testable or observable; thus, it is not science. How population Evolve Evolution is about a change in a trait within a population. In other words, populations, not individuals, evolve. Population: A group of organisms of a single species living together in the same geographic area. Genes interact with the environment to determine traits. The diversity of a population is linked to the genetic diversity of individuals within that population. Thus, evolution is the change in allele frequency over time. Microevolution: pertains to evolutionary change within populations. Population Genetics: field of biology that studies the diversity of populations at the level of a gene. Interests in how genetic diversity in populations changes over generations, as well as forces that cause a population to evolve. Study microevolution by measuring the diversity of a population in terms of allele and genotype frequencies. Pepper Moth Example: a single gene for body color has two alleles: D – Dark colored (dominate to d) d – Light colored Within two alleles there are three possible genotypes o DD (homozygous dominant) – dark o Dd (heterozygous) – dark o dd (homozygous recessive) – light Allele Frequencies Gene pool: the alleles of all genes in all individuals in a population. Allele frequency: percentage of each allele in a population’s gene pool. HardyWeinberg Equilibrium: allele frequencies do not change overtime in a population. A mathematical model to estimate genotype frequencies of a population that is in genetic equilibrium. P^2 + 2pq + q^2 The HardyWeinberg principle is only met if: No mutation No migration Large gene pool: the population is very large Random mating No selection Kinds of Natural Selection:
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'