genetic variation

• random fertilisation further increases genetic variation
• there are (2^n)^2 (with random fertilisation) possible chromosome combinations in gametes as it is random which egg and sperm will fertilise so variation is increased
• chromosome mutations are mutations in the number of chromosomes that can arise spontaneously by chromosome non-disjunction during meiosis
• non disjunction is when chromosomes or chromatids do not split equally during anaphase
• polyploidy is changes a whole set of chromosomes that occur when organisms have three or more sets of chromosomes than the usual two
• in polyploidy all chromosomes fail to split equally
• aneuploidy is changes in the number of individual chromosomes
• sometimes just individual homologous pairs fail to separate during meiosis
• aneuploidy usually results in a gamete having one more/fewer chromosome (downs syndrome)