Evolution

    Cards (75)

    • definition of evolution
      the change over time in the proportion of individuals in a population differing in one or more inherited traits
    • what are the 2 random processes in evolution?
      natural selection and sexual selection
    • what is the name of the random process in evolution?
      genetic drift
    • what do the random and non random processes of evolution cause?
      changes in allele frequency
    • how does natural selection work?
      acts on genetic variation in populations
    • what happens when a population produces more offspring than the environment can support?

      individuals with better suited variations to the environment survive for longer to produce more offspring, this passes on the alleles that conferred an advantage
    • what does natural selection result in?
      the non random increase in frequency of advantageous alleles and non random decrease in frequency of deleterious alleles
    • what arises as a result of mutation?

      variation
    • what is the original source of new sequences of DNA?
      mutations
    • what type of alleles come from the new sequences of DNA?
      novel alleles
    • what are the most common types of mutation?
      harmful or neutral
    • what benefits the fitness of an individual?
      a beneficial mutation
    • what type of process is sexual selection?
      non random
    • a selection of alleles that increases the individual's chances of mating and producing offspring is...
      sexual selection
    • what is an important factor in reproduction?
      mutual attraction
    • what makes an individual more attractive to the opposite sex?
      traits
    • examples of conspicuous physical traits
      pronounced colouration, increased size, striking adornments and elaborate courtship
    • what effect do conspicuous physical traits have on an animal's survival?
      decrease survival chances but increase success of obtaining mates
    • what does "higher fitness" mean?
      greater success in obtaining mates
    • what can sexual selection lead to?
      sexual dimorphism
    • what is sexual dimorphism?
      physical differences between males and females of the same species
    • examples of sexual dimorphism
      size, (males often are large than females) colouration, (female is inconspicuous and cryptically coloured to remain camouflaged on the nest. Males are conspicuously coloured for courtship and territorial behaviour) additional body parts (males have adornments e.g. antlers)
    • what 2 things determine reproductive success?
      male-male rivalry and female choice
    • examples of male-male rivalry strategies
      superior size an weaponry
    • how do females choose a mate?
      assess the fitness of males
    • what does an impressive courtship display or good appearance indicate?
      healthy male, low parasite burden and presence of advantageous genes
    • how does genetic drift occur?
      chance
    • when does genetic drift occur?
      when chance effects cause unpredictable fluctuations in allele frequency from one generation to the next
    • what type of traits don't have selection pressures?
      neutral traits
    • why is genetic drift more important in small populations?
      alleles are more likely to be lost from the gene pool
    • what are the names of the 2 types of genetic drift?
      bottleneck effect and founder effect
    • when does the bottleneck effect occur?
      when a population size is reduced for at least 1 generation
    • what might cause a bottleneck effect?
      a natural disaster which reduces the population so that it rarely represents the actual genetic makeup of the initial population
    • what does the bottleneck effect result in?
      leaves smaller variation among surviving individuals
    • how does the founder effect occur?
      through the isolation of a few members of a population so the new gene pool isn't representative of the original gene pool
    • how does genetic drift affect a gene pool?
      certain alleles may be under-represented or over-represented as allele frequency changes
    • how do selection pressures affect the rate of evolution?
      strong selection pressures make the rate of evolution rapid
    • what are selection pressures?
      the environmental factors that influence which individuals in a population pass on their alleles
    • examples of biotic selection pressures
      competition, predation, parasitism and disease
    • examples of abiotic selection pressures
      temperature, light, humidity, pH and salinity
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