Income Exclusion Rule. DEFINITION of 'Income Exclusion Rule'. A rule that sets aside certain types of income as nontaxable. There are many types of income that qualify under this rule, such as life insurance death benefit proceeds, child support, welfare and municipal bond income. Income that is excluded is not reported anywhere on Form 1040.
Ancestral vs derived alleles. An ancestral allele or an ancestral trait (depending on whether you look at the phenotype or a t the genotype) is the trait/allele that was carried by the common ancestor of the taxon you consider.
From Wikipedia, the free encyclopedia. Allelic exclusion is a process by which only one allele of a gene is expressed while the other allele is silenced. For autosomal genes, diploid organisms inherit one copy from each parent.At least two distinct selection events can lead to allelic exclusion.On one hand, one allele of the gene can be transcriptionally silent, which would result in the expression of only the second allele.or autosomal genes, diploid organisms inherit one copy from each parent. At least two distinct selection events can lead to allelic exclusion. On one hand, one allele of the gene can be transcriptionally silent, which would result in the expression of only the second allele.