Linkage

• Autosomal Linkage - when 2 genes are on the same (non sex) chromosome
• In autosomal linkage, there is a lack of variation, with most offspring having their parents genotype. There will be a few offspring with new genotype due to crossing over.
• Sex determination - sex in mammals is determined by two chromosomes, known as the sex chromosomes or heterosomes. The X chromosome is larger and contains about 2000 genes, whereas the Y chromosome contains fewer than 100.
• Sex linkage - Genes that occur on the sex chromosomes are said to be sex linked. In humans, males are heterogametic sex whereas females are homogametic. Most of the X chromosome doesn't have a homologous pair on the Y chromosome and the Y chromosome is effectively empty of genes. This means rhat only a single allele needs to be present on the sex chromosomes of men to be expressed.