Relationships between gene diversity and organismal evolution

动物进化出多种基因家族，通过基因复制和结构域改组参与细胞间的通讯和发育控制。每个科包括几个具有不同结构和功能的亚型或亚科，这些亚型或亚科在寄生虫和真生动物分化之前通过基因复制和结构域改组而分化。自从与原口动物分离以来，脊椎动物在鱼类与四足动物分离之前的早期进化中，通过进一步的基因复制，扩大了同一亚科成员（同种异构体）的多样性。为了更准确地了解异构体重复的时间，我们对文文鱼belcherbranchiostoma， an amphioxus, burgeri Eptatretus， a hagfsh和Lampetra reissneri的蛋白酪氨酸激酶家族的4个不同亚型、蛋白酪氨酸磷酸酶家族的5个亚型和其他3个基因家族进行了分离和测序。根据最大似然（ML）方法推导出的各亚科的系统发育树，以及基于ML方法的自举分析，我们发现同种异构体重复经常发生在脊椎动物的早期进化中，在环口动物和颌口动物分化前后或之前，通过基因重复和可能的染色体重复发生。

Animals evolved a variety of gene families involved in cell-cell communication and developmental control by gene duplication and domain shuffling. Each family comprises several subtypes or subfamilies with distinct structures and functions which diverged by gene duplications and domain shuffling before the divergence of parazoans and eumetazoans. Since the separation from protostomes, vertebrates expanded the multiplicity of members (isoforms) in the same subfamily by further gene duplications in their early evolution before the fish-tetrapod split. To know the dates of isoform duplications more closely, we have conducted isolation and sequencing of genes belonging to four different subtypes of the protein tyrosine kinase family, five subtypes of protein tyrosine phosphatase family, and other three gene families from Branchiostoma belcheri, an amphioxus, Eptatretus burgeri, a hagfsh and Lampetra reissneri, a lamprey. From a phylogenetic tree of each subfamily inferred from a maximum likelihood (ML) method, together with a bootstrap analysis based on the ML method, we have shown that the isoform duplications frequently occurred in the early evolution of vertebrates around or just before the divergence of cyclostomes and gnathostomes by gene dupli-cations and possibly chromosomal duplications.