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2010-10-02 17:34:24
Evolution natural selection

Flashcards for BIO 1 class
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  1. List the properties of life
    • Cellular organization
    • Metabolism
    • Homeostasis
    • Reproduction
    • Growth
    • Heredity
  2. Cellular organization is composed of...
    One or more cells
  3. What is a cell formed out of?
    Large molecules that contain carbon as a major component
  4. What are the 2 cell types?
    Prokaryotic and eukaryotic
  5. Define metabolism
    When a cell obtains and uses energy
  6. What are examples of work a cell does?
    • Building molecules
    • Moving of cell structures
    • Growing of cells
    • Production of new cells
  7. Define homeostasis
    Maintain stable internal conditions within and among cells
  8. Define reproduction
    Produce offspring similar to parents, due to passing of genes from parent to offspring
  9. Define growth
    Increase in size due to increase in number of cells and increase in size of each cell after it is formed
  10. Define heredity
    Posses genetic information in the form of DNA molecules
  11. DNA
    Deoxyribonucleic acid
  12. What is the theory of evolution?
    • Descent w/modification
    • Species arise from a series of ancestors, lead back to a common one
    • Characteristics of new species differ from its ancestors and other descendants
  13. What is natural selection?
    • Process where individuals that have certain heritable characteristics survive and reproduce at higher rates
    • Can increase adaptation of the members of a population to their environment
  14. What were Darwin's observations?
    • Individuals in a population differ in their traits, which are heritable
    • Members of a population produce more offspring than can survive in environment
    • Competition for limited resources occurs among members of population
    • Individuals w/traits best suited to local environment have higher probability to obtain resources
    • Successful competitors survive and reproduce at higher rate
    • Higher proportion of individuals in next generation will have their traits
  15. Evolution occurs when?
    At the unequal reproductive success of individuals
  16. How do you know when natural selection has occurred?
    When the population adapts to its environment
  17. What is phenotypic variation
    Plasticity of characteristics
  18. What is an example of genetic shift being an evolutionary process?
    Smaller fish pass through mesh of gill nets and survive to reproduce, pass on genes for smaller size to their offspring
  19. Example of genetic shift
    Herds of elephants have a high proportion of members lacking tusks. Due to poaching, absence of tusks probably due to specific allele and not plasticity in tusk presence/size
  20. What is human harvesting
    Brings about rapid change in population traits
  21. What was observed in human harvested populations?
    Population traits shifted at rapid rates resulting in younger age/small size of reproduction
  22. Changes may be evolutionary in?
    Genetic changes
  23. Changes may be non-evolutionary in?
    Phenotypic plasticity
  24. Is the environment ever constant?
    No, the rate of change varies over time and place
  25. Members of a population may experience environment change due to?
    • Movement to new environment
    • Shifts within environment
  26. What are some recent shifts within the environment?
    Global warming, human harvesting
  27. What are some past shifts within the environment?
    Continental drift, cold climates of ice age
  28. When the environment first changes, what happens to the members of the population?
    May not be as well adapted
  29. Traits
    • Only inheritable traits can pass from one generation to the next
    • Acquired characteristics aren't inherited
    • Most traits don't possess a natural selective value
    • The favorable/unfavorable value of a trait depends on environment in which it occurs
    • Adaptive value of trait can change if environment changes
  30. How does evolution result from natural selection?
    • Populations w/distinctive traits arise from ancestral populations lacking those traits
    • Over time different and distinctive populations have come and gone
  31. What are some direct observations of evolutionary change?
    • Humans drive natural selection and population evolution
    • Evolution in natural populations
  32. Examples of humans driving natural selection and population evolution
    • Harvested populations
    • Insects to pesticides
    • Bacteria to antibiotics
  33. Examples of evolution in natural populations
    • Plant population adaptation to extreme soils (population adapts to a specific type of soil, produces endemics)
    • Animal population adaptation to extreme conditions
  34. Define endemic
    Species which is unique to a place
  35. What are fossil records?
    The preserved traces of extinct organisms
  36. What can fossils be used for?
    Trace the origin of a group of organisms and the examination of changes that occur over time
  37. What kind of evidence is provided by fossil records?
    Change of life on earth over history of life
  38. Older fossils
    Least complex
  39. Younger fossils
    Contain more complex structures
  40. Distribution of fossil in the earth layers
    Coincides w/expected evolutionary result of increase in complexity of living organisms over time
  41. Define homology
    • Characteristics shared by a group of organisms which had a common ancestor
    • Basic similarity present but modification in structure reflect altered functions in the various descendants
  42. What does homology represent?
    The theme of descent w/modification
  43. What are the 2 types of homology?
    Structural and molecular homology
  44. What is structural homology?
    Structure has been modified for a variety of functions
  45. What is an example of structural homology?
    • The limbs of vertebrates, especially the forelimbs
    • Terrestrial vertebrates all have the same basic forelimb bones
  46. What is molecular homology?
    Shared molecular structures of genetic material
  47. Where was the genetic code originated?
    The common ancestor of all living organisms
  48. Define genetic code
    The triplet of nucleotide sequences in DNA which code for the amino acids in a protein
  49. Shared genes
    • Some genes are universally shared, retain similar functional properties in all types of cells
    • Some genes have similar molecular structure but different functional properties in different types of organisms
  50. Define biogeography
    Geographic distribution of species
  51. What occurs in biogeography?
    • Organisms move due to their own actions and due to movements of the continents
    • The observed distributions of current and extinct species matched the expected distribution based on evolutionary theory
  52. What is an example of biogeography?
    Species of large flightless birds found in South America, Africa, Australia and New Zealand. These birds are closely related even if they were found on different continents
  53. Define population
    A group of individuals of the same species that live in an area and interbreed and produce fertile offspring
  54. Evolution results from?
    Changes within a population
  55. Natural selection acts on?
    Individuals in a population
  56. How do populations evolve?
    The differential survive and reproduction of its members produces changes in population
  57. Define microevolution
    • Change within a population/species from generation to generation
    • Change in allele gene frequencies in population
    • Adaptation to an environmental factor
  58. Define macroevolution
    Changes of sufficient magnitude to produce new species
  59. Define phenotype
    Observable form of trait in an organism
  60. Define genotype
    • Pair of alleles for specific gene present in an individual
    • Formed of pairs of alleles
  61. One allele of the gene comes from?
    Each parent
  62. Explain heredity
    • A gene determines a trait
    • Alternate alleles of gene produce different forms of trait
  63. Example of heredity:
    Garden pea plant flower color
    • Gene: codes for the trait of flower color
    • Alleles: (P) - purple color, (p) - white color
  64. Define population genetics
    Study of the properties of genes in populations
  65. What happens in a non-evolving population?
    Each allele of a gene occurs at a certain frequency in the population
  66. Example of non-evolving population:
    Mosquito population of Mumbai, India before introduction of DDT
    • Gene: detoxifying
    • Non-resistant allele: 0.98
    • Resistance allele: 0.02
    • These frequencies remained constant through many generations
    • Non-resistance allele is unable to detoxify DDT
    • Resistance allele can detoxify DDT
  67. Define haploid
    1 allele resent in the cell
  68. Define diploid
    2 alleles present in a cell
  69. What is the Hardy-Weinberg Principle?
    Allele frequencies in a population which isn't evolving are unchanging frequencies of alleles and genotypes remain constant from generation to generation
  70. What does the Hard-Weinberg Principle require?
    • A large populations w/random mating
    • No input of new alleles
  71. What does the Hardy-Weinberg Principle equation describe?
    • The frequencies of the 3 genotypes formed from a gene w/2 alternate alleles
    • When the allele frequencies are in equilibrium
  72. What is the Hardy-Weinberg Principle equation?
    p2 + 2pq + q2 = 1
  73. What does p2 describe in the Hardy-Weinberg equation?
    Frequency of individuals w/2 copies of the more common allele
  74. What does 2pq describe in the Hardy-Weinberg equation?
    Frequency of individuals w/1 copy of each allele
  75. What does q2 describe in the Hardy-Weinberg equation?
    Frequency of individuals w/2 of the less common allele
  76. What is wrong with the Hardy Weinberg hypothesis?
    • Predicts no difference in the frequencies being measured
    • No factors are acting on the population to change the frequencies of the alleles
    • Some factor(s) are acting on the population to change the frequencies of the alleles
  77. When can the Hardy Weinberg null hypothesis be accepted?
    If from generation to generation the genotype and allele frequencies math those predicted by Hardy-Weinberg and remain unchanged
  78. When can the Hardy Weinberg null hypothesis be accepted?
    If after one or several generation, genotype frequencies don't match those predicted by the Hardy Weinberg equation
  79. The mosquito example
    • Pre-DDT frequencies remained constant for many generations
    • Presence of a DDT resistance gene was unknown because natural selection factor wasn't introduced to the population
    • If environmental conditions didn't change, allele frequencies remained constant
    • DDT was introduced when environment changed, natural selection acted on individuals of population
    • Fittest individuals survived and reproduced (those w/resistance gene)
    • Hardy-Weinberg equilibrium was broken, gene frequencies changed
    • Microevolution occurred in mosquito population
  80. What are the factors affecting the Hardy-Weinberg equilibrium?
    • Variation is produced in the population (mutation and sexual reproduction)
    • Allele frequencies are altered (natural selection, genetic drift, gene flow)
  81. What is a mutation?
    • It's a change in the nucleotide sequence of the DNA
    • In an existing allele, may produce a new type of allele of the gene
    • The change in the nucleotide sequence may alter the way the trait is formed from that new allele of the gene
  82. What is the ultimate source of new alleles?
  83. When must a mutation occur?
    In the potential germ cells (egg/sperm) to be passed to offspring and into the population
  84. What do most mutations produce?
    • Alleles that are neutral (not changing the phenotype)
    • Alleles that are slightly/severely negative (producing a harmful phenotype)
  85. Can mutant alleles be beneficial?
    • Yes, on rare occasions. Its phenotype makes the bearer better suited to the environment and enhances reproductive success
    • Over time and in large populations, alleles can produce favorable traits in their bearers, these are ultimate sources of variation in a population
  86. How many mutations occur in cells?
    1 mutation in every 100,000 cell divisions
  87. How many mutations occur in germ cells?
    Very few mutations
  88. What happens during sexual reproduction?
    • Produces unique combinations of alleles in each individual
    • Formation of egg and sperm shuffles alleles of each parent into a unique set in the gamete
    • Union of egg and sperm produces new combination of allele pairs
  89. What does fertilization bring together?
    Gametes of individuals w/different genetic backgrounds
  90. What provides a great genetic variation?
    Mixing of alleles into new combinations in the individuals of a population
  91. What does mutation and sexual reproduction both produce?
    Genetic and phenotypic variation in the individuals of a population
  92. Natural selection acts on the individuals of a population so that...?
    Those individuals whose traits are best suited to the environment leave a higher proportion of offspring in the next generation
  93. What does the environment determine?
    Which types of individuals are fittest, these are the individuals "selected"
  94. What does a gene flow do?
    Transfers alleles into/out of a population
  95. What is the result of a gene flow?
    Change in allele frequencies of the population
  96. What might a gene flow result from?
    • Migrations of individuals between populations
    • Movement of gametes
  97. What happens when allele frequencies of a source population differ from a population to which the individual moves?
    Frequencies of the receiving population may be changed
  98. Example of gene flow in the mosquito, Culex pipiens
    • Insecticide: organophosphate (not DDT) was used for 30 years
    • In Europe, a mutation producing a resistance allele occurred in mosquitoes
    • The resistance allele spread rapidly due to long distance migration of mosquitoes (wind)
    • Each area became resistance, mosquitoes w/allele kept being blown to new areas
    • Much of the world's mosquitoes became resistance after introduction of resistance allele
  99. Define genetic drift
    Random change in allele frequencies in a population
  100. What is the cause of genetic drift?
    Chance events
  101. Where does genetic drift occur most often?
    In small populations where events affecting a few individuals may have a large effect on the population
  102. Example of genetic drift: founder effect
    • Few individuals are isolated from a larger population and establish a new population
    • Type and frequency of alleles in new population are a subset of the source population, may differ depending on allele combination occurring in the founders
    • Rare alleles and combinations of alleles may be present in new population
  103. What are species?
    • A group of populations whose members are capable of interbreeding
    • Offspring are vigorous and fertile (healthy surviving offspring)
    • Reproductively isolated, can't produce fertile offspring w/individuals from different types of population (one kind of species can't reproduce w/another group)
  104. All populations of the species are united by what?
    Gene flow, this maintains their gene pool (individuals move from one population to another)
  105. Explain the gene pool populations of a species
    • Consists of all the alleles for genes in all individuals of the population
    • The frequency of any combination of alleles depends on the frequency of each allele in the population
  106. What happens if only one allele exists for a particular gene?
    That allele is fixed in the gene pool, all individuals have 2 copies of that allele
  107. What happens if two or more alleles exist for a particular gene?
    Each individual may have any possible combination of these alleles
  108. What is the biological species concept?
    An effective way of understanding the existence of different types of species population in nature
  109. What are some problems with the biological species concept?
    • Successful interbreeding can exist between different types of populations
    • Difficult to apply to populations which don't occur together
    • Many types of organisms are asexual, reproductive isolation doesn't apply
  110. Why is it difficult to establish criteria for defining species?
    There isn't a definite set of factors that maintain the identity of species in nature
  111. What factors promote reproductive isolation?
    • Reproductive isolating mechanisms
    • Prezygotic isolating mechanisms
    • Separated in space, fertile at different times, incompatible behaviors, structural differences (doesn't get to zygote stage)
    • Postzygotic isolating mechanisms
    • Genetic incompatibility of the gene sets of the parents
    • Hybrids developing to some extent, but die as embyros/juveniles (no further development than zygote)
    • Hybrid adults are weak, vigorous, and sterile
  112. What are prezygotic isolating mechanisms?
    Factors preventing mating and fertilization (zygote --> fertilized egg, single cell, individual)
  113. What are postzygotic isolating mechanisms?
    Factors interfering w/proper development and reproduction of the offspring
  114. What is speciation?
    • The formation of new species
    • 2 populations of a single species diverge
    • Reproductive isolation forms w/each of the 2 new species
    • Population gene flow is altered and slowed, interrupted
  115. What is allopatric speciation?
    • Populations become geographically isolated
    • Gene flow is restricted (cut off one species in population)
    • Gene pool of each population receives new alleles from mutation events
    • Genetic drift is small, isolated population may alter gene frequencies
  116. What happens as the separated populations evolve?
    Similarities decrease and reproductive barriers form
  117. Where does speciation occur in sympatric speciation?
    In populations that live in the same geographic area
  118. What happens during sympatric speciation?
    • Gene flow is reduced between separating populations while their members remain in contact
    • Reproductive barrier develops and separates the 2 populations
  119. What is an event that promotes sympatric speciation?
  120. What happens in polyploidy?
    • Accidents in gamete formation in offspring w/increased number of sets of chromosomes (2+ sets of chromosomes)
    • Such offspring may be reproductively isolated from parental population
  121. Where is it most common to find polyploidy to occur?
    In plants, and sometimes animals
  122. What is habitat differentiation?
    A subpopulation is enabled to utilize a resource or habitat not used by the parental population