Related Experiment Video
Updated: May 18, 2026
07:47
Microscopy of Fission Yeast Sexual Lifecycle
Published on: March 9, 2016
Have sex or not? Lessons from bacteria
1Université de Rennes 1, Campus de Beaulieu, Rennes, France. thierry.lode@univ-rennes1.fr
Summary
Meiotic sex in eukaryotes may have evolved to manage large DNA amounts during early cell formation, not primarily for reproductive advantage. It likely arose from a series of weak benefits from recombination and other reproductive events.
Area of Science:
- Evolutionary biology
- Molecular biology
- Genetics
Background:
- The evolutionary origins of sexual reproduction remain a significant puzzle in biology.
- Asexual reproduction in bacteria results in clonal populations, unlike the genetic variation seen in eukaryotes.
- Meiosis, a hallmark of eukaryotic sex, involves complex genetic processes not present in prokaryotes.
Purpose of the Study:
- To explore the potential origins of meiotic sex in proto-eukaryotes.
- To propose an alternative hypothesis for the evolution of sex, focusing on DNA management rather than direct reproductive benefits.
Main Methods:
- Conceptual analysis of evolutionary processes.
- Comparative genomics of prokaryotic and eukaryotic reproduction.
- Hypothetical reconstruction of early cellular events.
Main Results:
- Meiotic sex may have evolved to address challenges associated with large DNA quantities during proto-cell formation and genetic exchange.
- The evolution of sex could be a secondary consequence of primitive metabolic reactions and signaling pathways.
- Individual components of sexual reproduction (recombination, meiosis, gametogenesis, syngamy) may have offered weak, cumulative benefits.
Conclusions:
- Sex in eukaryotes might be an adaptation to manage genetic material rather than a direct driver of reproductive success.
- The evolution of sex is viewed as a stepwise process integrating various genetic and cellular mechanisms.
- Understanding sex's origins requires considering early cellular evolution and DNA management strategies.
Related Concept Videos
01:26Binary Fission
Binary fission is the primary mode of asexual reproduction in prokaryotes, such as bacteria. It results in the production of two genetically identical daughter cells. This highly efficient process ensures the rapid propagation of bacterial populations under favorable conditions and involves coordinated cellular and molecular events.DNA Replication and SeparationThe process begins with the replication of the bacterial chromosome. The circular DNA molecule unwinds at a specific origin of...
01:20Binary Fission
Fission is the division of a single entity into two or more parts, which regenerate into separate entities that resemble the original. Organisms in the Archaea and Bacteria domains reproduce using binary fission, in which a parent cell splits into two parts that can each grow to the size of the original parent cell. This asexual method of reproduction produces cells that are all genetically identical.
01:30Bacterial Signaling
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
01:33Bacterial Transformation
In 1928, bacteriologist Frederick Griffith worked on a vaccine for pneumonia, which is caused by Streptococcus pneumoniae bacteria. Griffith studied two pneumonia strains in mice: one pathogenic and one non-pathogenic. Only the pathogenic strain killed host mice.
Griffith made an unexpected discovery when he killed the pathogenic strain and mixed its remains with the live, non-pathogenic strain. Not only did the mixture kill host mice, but it also contained living pathogenic bacteria that...
Griffith made an unexpected discovery when he killed the pathogenic strain and mixed its remains with the live, non-pathogenic strain. Not only did the mixture kill host mice, but it also contained living pathogenic bacteria that...
01:28Yeast Signaling
Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes (cells with a nucleus). Cell signaling in yeast is similar to signaling in other eukaryotic cells. A ligand, such as a protein or a small molecule released from a yeast cell, attaches to a receptor on the cell surface. The binding stimulates second-messenger kinases to activate or inactivate transcription factors that further regulate gene expression. Many of the yeast intracellular signaling cascades have similar...
01:19Conjugation
Conjugation is a form of horizontal gene transfer that primarily occurs in bacteria and some archaea, promoting genetic diversity and adaptation. Bacteria can acquire resistance genes through conjugative plasmids, allowing them to survive antibiotic treatments that would otherwise be lethal. This process involves direct contact between cells through specialized structures such as the sex pilus and is mediated by conjugative plasmids, including the F (fertility) factor.Conjugation requires...