The pattern and process of gene family evolution

TL;DR

This paper reviews models and methods for understanding gene family evolution across all domains of life, emphasizing birth-death processes, probabilistic reconciliation, and the role of gene transfer, with data from the HOGENOM database.

Contribution

It introduces advanced models combining gene birth-death processes with phylogenetic reconciliation to analyze gene family evolution across diverse species.

Findings

Gene family size distributions are similar across domains of life.

Gene loss rates exceed duplication and transfer rates.

Gene transfer is the predominant birth event in prokaryotes.

Abstract

Large scale databases are available that contain homologous gene families constructed from hundreds of complete genome sequences from across the three domains of Life. Here we discuss approches of increasing complexity aimed at extracting information on the pattern and process of gene family evolution from such datasets. In particular, we consider models that invoke processes of gene birth (duplication and transfer) and death (loss) to explain the evolution of gene families. First, we review birth-and-death models of family size evolution and their implications in light of the universal features of family size distribution observed across different species and the three domains of life. Subsequently, we proceed to recent developments on models capable of more completely considering information in the sequences of homologous gene families through the probabilistic reconciliation of the phylogenetic histories of individual genes with the phylogenetic history of the genomes in which they have resided. To illustrate the methods and results presented, we use data from the HOGENOM database, demonstrating that the distribution of homologous gene family sizes in the genomes of the Eukaryota, Archaea and Bacteria exhibit remarkably similar shapes. We shown that these distributions are best described by models of gene family size evolution where for individual genes the death (loss) rate is larger than the birth (duplication and transfer) rate, but new families are continually supplied to the genome by a process of origination. Finally, we use probabilistic reconciliation methods to take into consideration additional information from gene phylogenies, and find that, for prokaryotes, the majority of birth events are the result of transfer.