Press release: Male yellow crazy ants are real-life chimeras

No. 64 - 27.04.2023

International research team identify novel reproduction system in animals

The Yellow Crazy Ant Anoplolepis gracilipes, is named after its erratic movements when disturbed. It is one of the worst invasive animals in the world, threatening populations of the Red Land Crab on Christmas Island, or forming supercolonies tens of kilometres across in northern Australia. But it turns out there is another reason why these insects stand out from the rest of the animal kingdom. As discovered by an international research team from Switzerland, Thailand and Germany, including the University of Göttingen, bodies of male Yellow Crazy Ants are composed of a mosaic of cells from two different, genetic lineages. The research was published in Science.

This finding is extremely unusual, and thus far not identified in any other living creature. In most animals including humans, each cell contains the genetic information from both the male and the female lineage at the same time, forming diploid cells with a double set of chromosomes. This is also true for queens and workers of social insects. In contrast, males of social insects develop from unfertilized eggs, forming bodies made of haploid cells with one set of chromosomes. Here in the Yellow Crazy Ant, however, males consist of cells with either one or the other set of chromosomes, making them real-life, genetic chimeras.

While chimerism is extremely rare in animals, it is the norm in the Yellow Crazy Ant. Dr Jochen Drescher, now a postdoctoral researcher at the University of Göttingen, carried out initial experiments as part of his PhD research at the University of Würzburg. Drescher says: “Even from my preliminary breeding experiments, where I genotyped queens, the sperm they were carrying as well as their offspring, it was clear that the Yellow Crazy Ant have an unusual reproductive mode, and it showed particularly in the males.” Subsequent research using new markers and additional analyses finally established that males of this species are indeed genetic chimeras. “Many questions remain unanswered,” explains Drescher. “No-one knows whether other organisms show this type of reproductive system where male and female lineages compete with one another, or how it contributes to YCA’s success as an invader, for instance, by bypassing negative effects of inbreeding.”

Original publication: H. Darras et al., Obligate chimerism in male yellow crazy ants, Science 380: 6640, 55-58, Science 2023, DOI: 10.1126/science.adf0419

Contact:

Dr Jochen Drescher

University of Göttingen

Faculty of Biology and Psychology

JFB-Institute of Zoology & Anthropology

Animal Ecology Group, SFB990-EFForTS

Untere Karspüle 2, 37073 Göttingen, Germany

Tel: +49 (0) 551 39 25800

Email: jdresch@gwdg.de