Review 1.txt

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nightrider89
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Review 1.txt
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2013-10-02 22:04:30
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biology
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ccsf biology 100b review 1
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  1. 1. What are the core principles of evolution?
    • -All life is linked through common ancestor
    • -populations change with time (evolve)
    • -environment influences this change (natural selection)
    • -advantageous traits are selected over less-advantageous traits
    • -advantageous traits become more common in the population (descent with modification)
  2. 2A. Why was the time "ripe" (for scientific developments) for Darwin to develop his evolutionary theory of the origin of species? 2B. What are the fundamentals of Darwin's theory of natural selection?
    • A. -Observation of fossils (Cuvier)
    • -Lyell's Principles of Geology--evolution of land forms is gradual
    • -Lamarck's ideas about inheritance of acquired characteristics
    • -Russell Wallace's observation in Indonesia
    • -Island Species:
    •       -derived from mainland species
    •       -encounter different environment on islands
    •        -change over time

    • B. too any individuals produced for limited resources
    • -those individuals with traits more suited to environment survive and reproduce
    • -their traits dominate in next generations, changing the set of traits in that population
  3. 3. What are the two basic requirements that must be met for adaption by natural selection to occur?
    • -there must be heritable variation for some trait. i.e. beak size, color pattern, thickness of skin, fleetness
    • -there must be differential survival and reproduction associated with the possession of that trait
    • -adaption cannot occur if both of these are not met.
  4. 4. Describe evidence that has been gained from paleontology, biogeography, anatomical homologies, molecular homologies, embryology and experiments to support the theory of evolution?
    • biogeography
    • -new environments create new niches
    • -stimulated speciation
    • -adaptive radiation

    • anatomical homologies
    • -similarity resulting from common ancestry

    • comparative embryology
    • - reveals additional anatomical homologies not visible in adult organisms
    • experimental observations
    • -differential predation leads to adaptive evolution in guppy populations
  5. 5. what is the smallest unit of evolution? why?
    • -population = smallest unit of evolution
    • -natural selections acts on individuals, but populations evolve
    • -genetic variations in populations lead to evolution
  6. 6. what is the material of evolution and why?
    • genotype
    • genetic makeup of an organism
    • alleles--variant forms of a gene

    • phenotype
    • observable traits of an organism (physics/behavioral) 

    • gene pool
    • collection of all alleles in a population
  7. 7. Describe how changes in gene frequencies can be caused by: gene mutations, sexual recombination, genetic drift, gene flow, non-random mating, and natural selection
    • gene mutations
    • -permanent alterations of organism's DNA
    • -cause new genes and alleles to arise
    • -effect:
    •        none 
    •        harmful
    •        accumulation of beneficial mutations lead to evolution
    • -two types:
    •      -point mutation
    •      -chromosomal mutation i.e. deletion, insertion, duplication

    • -gene duplication
    • -genomes may gain new functions
    • -may increase amount of gene product
    • -gene expression may diverge in different tissues or at different times in development
    • -one copy may accumulate deleterious mutations
    • -one copy retains original function, the other changes and evolves a new function
    • -ie Hox gene in vertebrate evolution

    • -lateral gene gene transfer
    • -movement of individual genes, organelles or genome fragments from one lineage to another
    • -pick up DNA fragments directly from environment
    • -genes transferred to new host in viral genome
    • -hybridization
    • -advantageous by incorporating novel genes

    • -genetic drift
    • -change alteration of allele frequencies
    • -sampling effect--loss of genes by chance
    • -largest effect in small population
    • -genetic drift increased in small population resulting from

    • -founder effect
    • -small population migrates to a new area with new small population with limited gene pool
    • -bottleneck effect
    • -serverity temporary reduction in population size
    • -limits genetic diversity to few surviving individuals in population, reducing gene pool
    • -gene pool usually no longer reflective of original gene pool

    • -gene flow
    • -movement of allele from one population to another
    • -causes a population to gain or lose alleles
    • -increases allele variation within population
    • -reduces differences between populations over time

    • -variation due to chance of event--neutral
    • -geographic variation between population i.e. mice separated by geographic mountain
  8. 8. How do mutations and sexual recombination lead to genetic variation
    • -gene mutations
    • -permanent alterations of organism's DNA
    • -cause new genes and alleles to arise
    • -effect:
    •      -none
    •      -harmful
    •      -accumulation of beneficial mutations lead         to evolution
    • -two types
    •      -point mutation
    •       -chromosomal mutation i.e. deletion,       insertion, duplication

    • -sexual recombination
    • -sources of genetic variation:
    •      -crossing over
    •      -independent assortment
    •      -sharing of gametes
    • -does not directly influence allele frequency
    • -in sexually reproducing populations, sexual recombination more important than mutation in producing genetic differences that make adaption possible
  9. 9. What are two types of gene mutation
    • -point mutation
    • -chromosomal mutation (deletion, insertion, duplication)
  10. 10. describe how genetic drift is increased in small populations from the founder effect and the bottleneck effect
    • -genetic drift:
    •      -change alteration of allele frequencies
    •           -sampling effect--loss of genes by     chance
    •      -largest effect in small population
    •      -genetic drift increased in small population resulting from
    • -founder effect
    • -small population migrates to a new area with new small population with limited gene pool
    • -bottleneck effect
    • -serverity temporary reduction in population size
    • -limits genetic diversity to few surviving individuals in population, reducing gene pool
    • -gene pool usually no longer reflective of original gene pool
  11. 11. compare and contrast intrasexual and intersexual selection
    • -intrasexual
    • -direct competition among individuals of one sex for mates of the opposite sex
    • -intersexual
    • -individuals with traits that attract mates favored
  12. 12. Give an example of each of the three types of natural selection (directional, disruptive, stabilizing)
    • -directional
    • -phenotype/genotype moves toward one end of the range
    • -pepped moth, Galapagos finches
    • -disruptive
    • -individuals at extremes of phenotype/genotype ranges favored over intermediates
    • -black bellied seed crackers
    • -stabilizing
    • -favors intermediate variants
    • -reduced variation
    • -maintains predominant phenotypes/genotypes
    • -human birth weight
  13. 13. how does lack of genetic variability limit natural selection?
    • -bottleneck incidents cause loss of some alleles from the gene pool
    • -this reduces individual variation and adaptability
    • -examples: cheetah--genetic variation in wild populations is extremely low
  14. 14. describe how diploidy and balancing selection preserve genetic variation?
    • -diploidly (recessive alleles)
    • -balancing selection (2+ phenotypes selective advantage):
    •      -heterozygote advantage
    •      -frequency-dependent selection
  15. 15. What 5 conditions must be met for a population to be considered "non-evolving"? Is it possible to predict allele frequencies in non-evolving population? How?
    • -Hardy-Weinberg Equilibrium
    •     -extremely large population
    •     -no gene flow
    •     -no mutations
    •     -random mating
    •     -no natural selection
    • -possible to predict approximate genotype frequencies from allele frequencies
    • -help identify mechanisms of evolutionary change
  16. 16. What is binomial nomenclature and in which ways is it still relevant?
    • -18th century, Carolus Linnaeus published a system of taxonomy based on resemblances
    • -binomial: two part scientific name of a species
    •      -first part of the name is Genus
    •      -second part of the name is the species epithet unique for each species in genus
    •      -Genus + species epithet = species
    •      -format:
    •      -first letter of Genus is capitalized
    •      -entire species name is italicized or underlined
    •       -useful because there are two part names for species and hierarchal classification
  17. 17. how does analogies lead to potential misconceptions in constructing phylogeny? how does convergent evolution lead to analogies?
    • -Analogous
    • -Analogy: similarity due to convergent evolution rather than shared ancestry
    • -Homoplasies: analogous structures or molecular sequences that evolved independently
    • -leads to misconception in phylogenies
    • -Convergent evolution
    • -occurs when similar environmental pressures and natural selection
    • -produce similar adaptions in organisms from different evolutionary lineages
  18. 18. describe the difference between a monophyletic, paraphyletic, polyphyletic grouping.
    • -monophyletic
    • -taxon which forms a clade, meaning that it consists of an ancestrall species and all its descendants
    • -paraphyletic
    • -consists of all descendants of the last common ancestor of the group's members minus a small number of monophyletic groups of descendants, typically just one or two such groups
    • -polyphyletic
    • -characterized by one or more homoplasies: appear to be the same but which have not been inherited from common ancestors
  19. 19. to construct the best phylogram/cladogram, systematists use the principles of maximum parsimony and maximum likelihood. Explain how they do this.
    • -fewest evolutionary events like base changes (maximum parsimony)
    • -genes evolves at same rate (maximum likelihood)
  20. 20. What is the molecular clock and how is it used to construct phylogenies?
    • -molecular clock uses the average at which a given gene or protein accumulates changes to gauge the time of divergence for a particular split in the phylogeny
    • -how to construct?

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