Genomic Perspectives on the Long-Term Absence of Sexual Reproduction in Animals

Abstract

Sexual reproduction, the exchange and recombination of genetic material between different individuals, is commonly viewed as one of the most important sources of genomic diversity in animals. This genomic diversity is subject to natural selection and, consequently, the fittest genomes relative to the environment survive and persist. According to this vision, the absence of sexual reproduction in animals is believed to inexorably lead to an evolutionary dead end as asexual animals become unable to adapt to changing environmental conditions. Yet, several animal lineages suspected to have been reproducing exclusively asexually for millions of years actually survived environmental changes and are not necessarily restricted to specialized ecological niches. The sources of genomic variations that have contributed to the evolutionary success and persistence of these lineages is currently unknown. Here we will review and discuss these known cases of long-term survival of asexually reproducing animal lineages with a focus on recent genomic findings.