Meiosis and mutations contribute to genetic variation in Natural Selection.

Describe how meiosis and different types of mutations contribute to genetic
variation and the role of this variation in natural selection.
Meiosis
• Crossing over occurs during prophase I
• Homologous chromosomes / chromatids overlap
• at points called chiasma/ chiasmata
• Genetic material is exchanged
• resulting in new combinations of genetic material


Random arrangement of chromosomes
• occurs during metaphase
• so that they separate in a random/ independent manner
• resulting in new combinations of genetic material


Mutations
• A gene/ (point and frameshift) mutation occurs
• as a result of a change in sequence of nitrogen bases
• in the DNA molecule
• A chromosome mutation occurs as a
• result of a change in the structure of a chromosome/ number of chromosomes
during meiosis
• Mutations that occur in sex cells
• are passed on to the new generations
• creating new characteristics


Role of variation in natural selection
• Organisms of a particular species shows a great deal of variation
• Some individuals may have characteristics that are favourable/ any example
• Others may have characteristics/any example that are unfavourable
• If there is competition/changing environmental conditions/ Selective pressure
by
the environment
• organisms with favourable characteristics survive
• and reproduce
• and pass these favourable characteristics to their offspring
• while organisms with unfavourable characteristics will die out
• Over time the whole population will have this favourable characteristic