 Yet another approach to microbial species uses genetic data to determine phylogenetic relations and assigns organisms to species according to those relations. Microbiologists use various types of genetic data for recognizing microbial species, such as 16S rRNA genes, DNA:DNA hybridization, ANI or average nucleotide identity, and core or house-keeping genes. Using such genetic data to classify microbes into species is complicated by the existence of lateral gene transfer. Lateral gene transfer occurs when microbes share genetic material with microbes near them. Lateral gene transfer is not the transfer of genetic material due to reproduction, but a different way microbes share genes. Lateral gene transfer is frequent in microbes. (See O’Malley 2014 for an explanation of lateral gene transfer.) Given the frequent occurrence of lateral gene transfer among microbes, different parts of a microbe’s genome will have different evolutionary histories. Microbiologists use different genes when classifying microbes into species. As a result, they obtain different classifications of species.