In a groundbreaking study of the yellow crazy ant, also known as Anoplolepis gracilipes, international scientists discovered that the male ants of this species are genuine chimeras, carrying two distinct genomes from different parent cells within their bodies. This unparalleled reproductive process starts from a single fertilized egg that undergoes separate maternal and paternal nuclear division, contradicting the fundamental principle of biological inheritance which proposes that an individual’s cells should all have the same genome. Photo courtesy of Hugo Darras.
Male yellow crazy ants manifest a unique trait of harboring two separate genomes, each held within different cellular clusters.
The yellow crazy ant, formally called Anoplolepis gracilipes, is infamous for being a damaging invasive species worldwide. However, the international research team’s focus is not on the ant’s destructive tendencies, but on its peculiar reproductive process. This is because the male ants of this species have been a source of intrigue for the scientific world.
“Prior genetic examinations of the yellow crazy ant indicated that the males of this species possess two duplicates of each chromosome. This was an astonishing finding, given that males typically develop from unfertilized eggs in ants, bees, and wasps, thereby having only one maternal copy of each chromosome,” clarified Dr. Hugo Darras, Assistant Professor at Johannes Gutenberg University Mainz (JGU), and lead author of the related article recently featured in Science.
“In light of this, we elected to delve deeper into this intriguing phenomenon with further experiments.”
Two male yellow crazy ants (Anoplolepis gracilipes). Photo courtesy of Hugo Darras
Two distinct genomes in separate cellular clusters
The team’s findings were remarkable. There was a general presumption that male yellow crazy ants carried the same pair of chromosome sets in every cell of their bodies. The researchers, however, established that this hypothesis was far from the truth.
“What we found was that the male ants have maternal and paternal genomes located in different cells of their bodies, making them actual chimeras. In other words, while all males have two genomes, each cell in their bodies contains just one of the two genomes,” Darras explained.
Typically, in any multicellular organism, be it a human, dog, or bat, all cells carry identical genetic material.
A cross-sectional view of the brain of a chimeric male yellow crazy ant with maternal (pink) and paternal (blue) genomes in situ hybridization: The male tissue comprises large cell clusters carrying only maternal or paternal genomes. Photo credit: Hugo Darras
The research group concluded that male yellow crazy ants are genuine chimeras: they originate from fertilized eggs where the two parental gametes do not combine. Instead, the maternal and paternal nuclei split separately within the same egg, resulting in adult males having both parental DNA sequences but in different body cells.
When the gametes do merge, either a queen or a worker ant develops from the egg, based on the genetic information the sperm carries. The mechanisms dictating whether or not parental gametes fuse remain unknown.
Chimerism in yellow crazy ants: A previously unknown reproductive method
Chimeras are organisms whose cells contain varied genetic materials. Such organisms naturally occur in specific species like corals and angler fish, where distinct individuals can amalgamate into one. Chimerism can also be observed in humans and other placental mammals, where a minor number of cells can be exchanged between the mother and the fetus during gestation, resulting in the offspring having a few cells identical to the mother’s genetic material. Similar small-scale exchanges can occur between twins in utero.
A male yellow crazy ant (Anoplolepis gracilipes). Photo credit: Hugo Darras
“Contrary to these familiar cases, chimerism in the yellow crazy ant does not result from the fusion of two separate individuals or a cellular exchange between them. Rather, this process originates from a single fertilized egg. This is truly unique,” Darras concluded.
Therefore, the evolution of the male yellow crazy ant seems to violate one of the core laws of biological inheritance, which stipulates that all cells of an individual should contain the same genome.
Reference: “Obligate chimerism in male yellow crazy ants” by H. Darras, C. Berney, S. Hasin, J. Drescher, H. Feldhaar and L. Keller, published on April 6, 2023, in Science. DOI: 10.1126/science.adf0419
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Table of Contents
Frequently Asked Questions (FAQs) about Yellow Crazy Ant Chimerism
What are chimeras in biology?
Chimeras in biology are organisms whose cells contain different genetic materials. They can occur naturally in certain species where separate individuals merge to become one. Chimerism can also be found in humans and other placental mammals, where a small number of cells can be exchanged between the mother and fetus during gestation.
How do male yellow crazy ants defy the laws of biology?
Male yellow crazy ants defy the laws of biology by exhibiting chimerism. Unlike typical males in other ant species, which develop from unfertilized eggs and have only one maternal copy of each chromosome, male yellow crazy ants have two copies of each chromosome. They possess maternal and paternal genomes in different cells of their bodies, making them chimeras.
What is the significance of the discovery of male yellow crazy ant chimerism?
The discovery of chimerism in male yellow crazy ants challenges the fundamental principle of biological inheritance, which states that all cells of an individual should contain the same genome. This unique reproductive process, originating from a single fertilized egg with separate maternal and paternal nuclear division, provides valuable insights into the diversity of reproductive strategies in nature.
Are chimeras common in the animal kingdom?
Chimeras are relatively rare occurrences in the animal kingdom. While they can be found in certain species like corals, angler fish, and some placental mammals, chimerism originating from a single fertilized egg, as observed in male yellow crazy ants, is a unique phenomenon. It adds to the diversity of reproductive mechanisms found in nature.
Can chimerism have any implications or effects on the yellow crazy ant population?
The implications of chimerism in the yellow crazy ant population are still being investigated. Understanding the mechanisms that determine whether the fusion of parental gametes occurs or not could shed light on the factors influencing the development of different castes (queens or workers) within the species. Further research may help uncover the potential impact of chimerism on the ants’ biology, behavior, and invasive capabilities.
More about Yellow Crazy Ant Chimerism
- Science: “Obligate chimerism in male yellow crazy ants” (DOI: 10.1126/science.adf0419) – Link
- Johannes Gutenberg University Mainz (JGU) – Link
- Yellow Crazy Ants – Link
- Genetic Inheritance – Link
- Chimeras in Biology – Link
- Reproductive Strategies in Nature – Link
