Modelling the evolution of multi-gene families.

A number of biological processes can lead to genes being copied within the genome of some given species. Duplicate genes of this form are called paralogs and such genes share a high degree sequence similarity as well as often having closely related functions. Some genes have become widely duplicated to form multigene families in which the copies are distributed both within the genomes of individual species and across different species. Statistical modelling of gene duplication and the evolution of multi-gene families currently lags behind well-established models of DNA sequence evolution despite an increasing volume of available data, but the analysis of multi-gene families is important as part of a wider effort to understand evolution at the genomic level. This article reviews existing approaches to modelling multi-gene families and presents various challenges and possibilities for this exciting area of research.