Animals that have no spinal column.

The relationships of groups of organisms as reflected by their genetic makeup.

The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.

DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.

Two identical genes showing the same phenotypic action but localized in different regions of a chromosome or on different chromosomes. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)

The genetic complement of an organism, including all of its GENES, as represented in its DNA, or in some cases, its RNA.

Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.