Evolution of two gene families controlling the fundamental processes of eukaryotic development: MADS-box gene family and homeobox gene family

MADS-box and homeobox genes form two large gene families of transcription factors that control fundamental processes of eukaryotic development. Therefore, studies of evolution of these gene families are expected to give some insights into the evolution of morphological characters. With this in mind, the following four related studies were conducted. (1) The origin and diversification of MADS-box genes controlling flowering in plants were studied. (2) The patterns of duplication and loss of MADS-box genes in the genomes of Arabidopsis and rice were studied. (3) A simple statistical method for predicting the gene regions that are functionally differentiated between duplicate genes was developed. (4) The pattern of duplication and loss of homeobox genes in the 11 species of bilateral animals was studied. Three general conclusions learned from the above four studies are as follows. (1) The duplication events of different lineages of MADS-box genes and homeobox genes often predate the origin of their related morphological characters. (2) These gene families have experienced frequent gene duplication events and losses. (3) Both gain and loss of these genes might have been important for the evolution of morphological characters.