Topic 7: evolution of populations Flashcards

• what does natural selection act on

  individuals
• how do populations evolve

  natural selection acting on individuals
• what is the smallest unit of evolutionary change

  population
• what is a population

  group of individuals of the same species that live in the same area and interbreed producing fertile offspring
• what is microevolution

  change in allele frequencies in populations over generations
• what is a genetic locus

  the combination of two alleles
• what are alleles

  different forms of a gene corresponding to different DNA sequences in each different form
• how many alleles per chromosome

  one
• alleles dont blend but when it appears that they did, what is it due to?

  incomplete dominance
• an individual in a population represents what in allele frequencies


  represents different combinations of alleles drawn from the gene pool
• variation in heritable traits is a prerequisite for what

  evolution
• Why is genetic variation advantageous to a population

  because it enables adaptation of the population to the enviornment via natural selection
• genetic diversity is one of the three main components of what


  biodiversity
• genetic variation among individuals is cause by what

  differences in genes or other DNA segments
• what is a phenotype


  product of inherited genotype and environmental influences
• natural selection can only act on variation with a what

  a genetic component
• not all phenotypic variation is what


  heritable
• new genes and alleles arise by what 2 possibilities

  mutation or gene duplication
• What are mutations?

  changes in an individuals DNA sequence
• what are two ways mutations are caused

  -small-scale (point mutation) or chromosomal errors in DNA (insertion/deletion)-structural damage to DNA (radiation)
• what are the only kinds of mutations that can be passed on to the next generation


  mutations in gametes
• mutations create new what


  alleles
• chromosomal mutations that delete, disrupt, or rearrange many loci are typically what

  harmful
• duplication of small DNA pieces increase what

  genome size
• duplication of small DNA pieces are usually less what

  harmful
• whole-genome duplication causes what

  duplication of genes that can take on new functions by further mutation
• most evolutionary change is based on what

  accumulation of many mutations with small individual effects
• how many new mutations are made in humans per generation

  ~60-100
• why do mutation accumulate quickly in prokaryotes

  because they have short generation times
• what have a lower mutation rate: eukaryotes or prokaryotes?

  prokaryotes
• what are the sources of genetic variation

  -mutations-sexual reproduction
• why is sexual reproduction a source of genetic variation

  can shuffle existing alleles into new combinations
• how does sexual reproduction shuffle existing alleles into new combinations (2)

  -random mating between organisms -recombination of homologous chromosomes during meiosis shuffles mutations to create new combinations of alleles
• In sexually reproducing organisms, what is more important in producing genetic differences making adaptation possible

  recombination is more important than mutation
• what are the three major factors that alter allele frequencies and bring about the most evolutionary change in populations

  1. natural selection2. genetic drift3. gene flow
• only natural selection causes what kind of evolution

  adaptive evolution
• what is adaptive evolution

  feature or trait that provides an advantage to an individual possessing it
• what is relative fitness

  the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
• natural selection only acts on what

  existing variation
• differential reproductive success of individuals in a population results in what


  certain alleles passed to the next generation in greater proportions