The finding by John M. Logsdon, Jr., assistant professor in the UI College of Liberal Arts and Sciences Department of Biological Sciences and the Roy J. Carver Center for Comparative Genomics, and colleagues from the UI and Roanoke College (Virginia), provides the first clear evidence that meiosis arose very early in eukaryotic evolution, bringing science one step closer to understanding the mystery of sexual evolution.
The paper, "A Phylogenomic Inventory of Meiotic Genes: Evidence for Sex in Giardia and an Early Eukaryotic Origin of Meiosis," describes their work studying eukaryotes (cells having nuclei, including plants, animals and fungi). By looking for genes necessary for sexual reproduction, the researchers uncovered evidence that eukaryotic cells have been capable of sex for a very long time. Recent evolutionary analyses of the genome of Giardia intestinalis, a unicellular protist (microbial eukaryote) parasite that represents an early-branching lineage of eukaryotes, has revealed the presence of numerous genes implicated in meiosis -- the cellular division process that results in gametes (haploid reproductive cells).
Logsdon says: "Most eukaryotes are known to have sexual cycles and meiosis, but such processes are unknown in some single-celled protists (protozoa). Despite over a century of study, Giardia intestinalis was not known to have a sex life. And since Giardia is thought to be a modern representative of one of the earliest diverging eukaryotic lineages, it was suspected to simply have never acquired meiosis. But the inability to observe processes does not necessarily mean that they are not present."