Evolution - review PDF

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Evolution Test Review

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Darwin vs Lamarck Theories Prezygotic or Postzygotic - Different types of isolation (with examples) Micro vs Macroevolution Evidence of Evolution (stations) How mechanisms affect allele population (genetic drift, bottleneck, gene flow etc…) Natural selection types Darwin’s theory of evolution Hardy-Weinberg

20 multiple choice and 5 long answer questions ____________________________________________________________________________ - Natural selection: - environmental conditions favour certain traits over others so organisms with advantageous traits will survive and reproduce, passing traits on to offspring those that do not will die along with their traits - Adaptation: - A process that helps the organism survive and reproduce in a particular environment - Speciation: - Is the evolutionary formation of new species (macroevolution) - Speciation is caused by changes in gene frequencies and phenotypic traits within populations

Microevolution vs Macroevolution Microevolution happens on a small scale (within a single population), while macroevolution happens on a scale that transcends the boundaries of a single species. Despite their differences, evolution at both of these levels relies on the same, established mechanisms of evolutionary change: mutation. ●

Microevolution - caused by changes in gene (allele) frequencies and phenotypic traits within populations ○ Eg: Bottleneck effect - A population of 10 000 with an equal amount of B and R alleles has been reduced to 100, now with 90% B and 10% R alleles. The genetic diversity has been drastically changed. ○ Founder effect ○ Natural Selection ○ Genetic drift

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Macroevolution - with sufficient changes over time, creates a new species (occurs over a long process) ○ Eg: Darwin’s finches ○ Speciation

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Different Types of Isolation ●

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Prezygotic - isolating mechanism that prevents interspecies mating ○ Ecological Isolation: live in different places ■ E.g. the Hoary Marmot lives at elevations in alpine meadows in the Canadian Rockies ○ Temporal Isolation: species breed at different times ■ E.g. the deep purple iris blooms in the summer ○ Behavioural Isolation: differences in courtship behavior ■ E.g. the jumping spider from Arizona has a unique mating dance where they shake their legs and wave their palps ○ Mechanical Isolation: species are isolated by their mechanics ■ E.g. a pink lady’s slipper orchid has uniquely shaped pollen sacs that are not removed by any other flower, only insects ■ Genitalia of the males and females may have different sizes ○ Gametic Isolation: when gametes come into contact, no fertilization occurs ■ E.g. different species of giant clams release sperm and eggs into open water, but each clam’s gametes are only recognized by special markers on each other ○ Reproductive Isolation - factors that prevent different species from reproducing ■ E.g. bowerbirds construct collections of sticks and decorate them with different colors in order to woo females. If two incipient species (new species form that can inter-breed) evolved differences in this mating ritual, it might permanently isolate them and complete the process of speciation. Postzygotic - isolating mechanism that prevents maturation and reproduction in offspring ○ Hybrid Infertility: hybrids are sterile ■ E.g. Donkey and horse produce an offspring, mule, which is infertile

Different Types of Selection ●

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Directional Selection ○ A mode of natural selection in which a single phenotype is favored, causing the allele frequency to constantly shift in one direction Stabilizing Selection

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A mode of natural selection in which an intermediate phenotype is favored over two extreme phenotypes, causing the genetic diversity to decrease as the population stabilizes Disruptive/Diversifying Selection ○ A mode of natural selection in which the extreme phenotypes are favored over the intermediate phenotype

Evidence for Evolution (stations) ● Fossil (paleontology) ○ It's the most direct evidence of macroevolution. Darwin used relative positions of rocks to determine when changes occurred, showing the evolution of organisms and links to their ancestors. ● Biogeography ○ Scientific study of geographic distribution of organisms based on both living species ● Comparative Anatomy ○ Homologous Structures ~ structures that are similar in structure but different in function (Ex: the wing of a bat and a human arm) ○ Vestigial Structures ~ Structures with no apparent function but resembles the structures of ancestors (toes, appendix, wisdom teeth) ■ Evolutionary baggage, were features that ancestors served a useful purpose but has become useless and greatly distorted as species evolve. ○ Analogous Structures ~ Structures with similar functions, but completely different structures (Ex: an insect wing and a bird wing) ■ They have evolved completely, and thus do not share a common ancestor ■ Evidence of convergent evolution due to their adaption to the selective pressures of their environment ● Comparative Embryology ○ Vertebrate embryos provide an extensive glimpse into evolutionary relationships ○ Scientists have found out that vertebrate embryos exhibit homologous structures during early phases of development, but become totally different structures in their adult forms

○ Embryos of existing organisms have characteristics of unrelated organisms, indication a link to a common ancestor ● Comparative Biochemistry/Genetics ○ Some basic types of organic compounds in cells of all organisms (DNA, proteins, amino acids sequences, lipids and carbohydrates) ○ The longer the time period since divergence, the greater the difference in substances ● Parallel Adaptation ○ Different geographical areas exhibit animal and plant species that are similar (converging pathways) ○ Species were isolated when continents split (divergent) but still evolved similarly since their environment were similar Genetic Variation ● Genetic Drift - changes to allele frequency as a result of chance ○ Genetic bottleneck: ■ A drastic, often temporary, reduction in population size, usually resulting in a significant genetic drift as gene variation is now limited ○ Founder effect: ■ Genetic drift that results when a small number of individuals separate from their original population and establish a new population ● Genetic Flow - migration of organisms causing a shift of alleles ● Non-random Mating - probability that two individuals in a population will mate is not the same for all possible pairs ● Mutation - greatest cause of genetic variability - If an advantageous mutation occurred through environmental factors, that gene would be passed on Darwin vs Lamarck: DIFFERENCES: Lamarck

1. This theory states that there is an internal vital force in all organisms. 2. According to this theory if an organ is constantly used

Darwin

1. This theory does not believe in the internal vital force. 2. An organ can develop further or degenerate only due to continuous

it would be better developed whereas disuse of organ results in its degeneration. 3. It does not consider struggle for existence. 4. All the acquired characters are inherited to the next generation. 5. Lamarckism does not believe in survival of the fittest.

variations. 3. Struggle for existence is very important in this theory. 4. Only useful variations are transferred to the next generation. 5. Darwin’s natural selection theory is based on survival of the fittest.

SIMILARITIES: - They both believed that species change over time - Both believed that creation was not created perfect by God Unlike most other people at the time, Charles Darwin (1809-1882) and Jean-Baptiste de Lamarck (1744-1829) both thought that life had changed gradually over time and was still changing, that living things change to be better suited and adapted to their environments, and that all organisms are related. Darwin and Lamarck also agreed that life evolved from fewer, simpler organisms into many, more complex organisms. THEORIES: Lamarck's Theory ● Species underwent changes in response to changes in their environment. One notable example quoted by him was the case as it might exist with respect to Giraffes. As trees began to grow taller, giraffes responded to the change by growing longer necks so that they could continue to feed. This newly developed gene would be passed on. ● This change was permanent for as long as the new environmental conditions continued to apply. Nature chose the best possible solution and, organisms (species), responded accordingly. Darwin's Theory ● Natural selection and survival of the fittest. As the environment underwent changes, the species affected by these changes underwent changes in response to changes in the environment. ● Mutation happened that caused a giraffe's ancestors to grow longer necks, and because those ancestors had better access to food than ones with shorter necks, they reproduced more, outnumbering and eventually replacing the short-neck ones.

Hardy-Weinberg -

States: In large population in which only random chance is at work allele frequencies will remain consistent from generation to generation

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5 conditions: - No natural selection: - All individuals have an equal chance of reproductive success - No mutations - No migration occurs: - No immigration or emigration - Random mating only - Population must be very large

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If these conditions are met, the population is at equilibrium - This means that there is no change or no evolution Any factor that causes the allele frequency to change leads to evolution: - Natural selection - Mutations - Migration - Non random mating - Small population

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Importance: - It provides equations that predicts the frequencies different genotypes in a stable gene pool - If the proportions of genotypes in a population match those predicted by the equations, then: - That population’s gene pool is stable - Locus in question us not under selective pressure - If the proportions are different, then the gene pool is under pressure - Since the conditions are rarely met, genetic equilibrium does not exist for long Formula:

p+q = 1 p2 + 2pq + q2 = 1 -

p = gene frequency of the dominant allele q = gene frequency of the recessive allele

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p2 = proportion of individuals in a population that are homozygous dominant 2pq = proportion of individuals in a population that are heterozygous dominant q2 proportion of individuals in a population that are homozygous recessive

Vocabulary: -

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Mutations create new genetic information and add genetic diversity to species Lamarck - was the first scientist to recognise that species evolved in response to their environment - Although his hypothesis of how species evolved has been proven wrong Darwin went around the world on the HMS Beagle, a  ship: - He visited Galapagos Islands - He observed that there is a link between finches with different beaks and the habitat in which they live in Artificial selection : - Process in which individuals with particular favoured traits in each generation are chosen as the breeding stock for the next generation - Over several generations, it can produce dramatic changes in the traits of a population - Although it is limited by the genetic variability within the initial breeding population - It reduces the overall genetic diversity of the population and therefore contribute to the loss of biodiversity Fossils: - the preserved remains or traces of animals, plants, and other organisms from the remote past - fossils are the most direct evidence of macroevolution Population: - All members of the same species living in the same region Species: - A group of populations whose individuals have the potential to interbreed and produce viable offspring Gene pool: - the total frequency of each allele within a population at any one time Gene: - The basic unit of heredity transmitted from generation to generation Allele: - A particular form of a gene; many genes have 2 or more alleles Microevolution: - A change in a population’s gene pool over several generations - Provide compelling evidence of evolution - Show that organisms have become more and more complex over time Homologous features:

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- features that are similar in structure but different in function Analogous features: - Features that are similar in function but different in structure Vestigial Features: - Remnants of organs or structures that had a function in an early ancestor Competition within populations: - All species produce more offspring than can survive to reproduce - Resulting in competition for resources between members of the same species Pseudogene: - A vestigial gene that no longer codes for a functioning protein Plate tectonics / paleontology: - The scientific theory that describes the large-scale movements and features of earth’s crust - Helped by fossils found in different continents Neutral mutation: - A mutation that does not result in any selective advantage or disadvantage Harmful mutation: - Any mutation that reduces the reproductive success of an individual Beneficial mutation: - Any mutation that increases the reproductive success of an organism Immutable: - Unable to change Catastrophism: - The theory that the pattern of fossils could be accounted for by a series of global catastrophes that wiped out most species on earth Uniformitarianism: - The theory that geological changes are slow and gradual Biogeography: - The scientific study of the geographic distribution of organisms based on both living species and fossils Radioisotope: - An atom that is unstable and that can decay Gene pool: - The complete set of all alleles contained within a species or population Genetic drift: - Changes to allele frequency as a result of chance Genetic bottleneck: - A dramatic, often temporary, reduction in population size, usually resulting in a significant genetic drift Founder effect:

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Genetic drift that results when a small number of individuals separate from their original population and establish a new population Speciation: - The formation of new species in the course of evolution (macroevolution)

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