Asexual Ants Have Sex

In 2009, researchers reported on an ant species that was completely asexual and propagated exclusively by cloning, not sexual reproduction - the fungus-farming ant Mycocepurus smithii. The research was published in Proceedings of the Royal Society B and the news flew round the world. Now, a new study reports on 4 Mycocepurus smithii populations that do have sex.



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From 2009:

All-Female Ant Species Found
April 17, 2009—Save the males? Too late for Mycocepurus smithii.

This leaf-cutter ant species is all female and thrives without sex of any kind—ever—according to a new study. The ants have evolved to reproduce only when queens clone themselves.

"They appear to have evolved a new mode of reproduction, and the genetic mechanisms have yet to be worked out," said lead study author Anna Himler, a research associate at the University of Arizona.

…No male of the species has ever been found, and "even if a male were theoretically to appear somewhere, we're not sure they could mate any more," she said.

Other ants, such as fire ants, that can reproduce asexually have working sexual organs, just in case.

Ants inhabit 'world without sex'

These ants do not need males

An Amazonian ant has dispensed with sex and developed into an all-female species, researchers have found.

The ants reproduce via cloning - the queen ants copy themselves to produce genetically identical daughters.

This species - the first ever to be shown to reproduce entirely without sex - cultivates a garden of fungus, which also reproduces asexually.

The finding of the ants' "world without sex" is published in the journal Proceedings of the Royal Society B.

WHERE HAVE ALL THE BOYS GONE?

Scientists have recently discovered that a species of fungus-gardening ant is the only ant species in the world known to have dispensed with males entirely.

…scientists have recently discovered that queens of the ant species Mycocepurus smithii reproduce without fertilization and males appear to be totally absent.

Animals that are completely asexual are relatively rare, which makes this is a very interesting ant. Asexual species don’t mix their genes through recombination, so you’d expect harmful mutations to accumulate over time and for the species to go extinct more quickly than others. They don’t generally persist for very long over evolutionary time.

From July 18, 2011, new research published in PNAS, reported by The Scientist:

Asexual Ants Have Sex

Birds do it. Bees do it. But until now, no one thought the fungus farming ant did it. …however, researchers have found evidence that some populations of Mycocepurus smithii actually do have sex…

…the fungus-farming ant is one of the few species that appeared to adopt a purely asexual lifestyle: researchers had never seen a male in the wild, and ants in the lab produced clonal offspring.

But …they found four Amazonian populations in which queens had a different genetic makeup than their offspring, indicating that those offspring were not simply the result of asexual cloning. …

When the researchers dissected the seemingly sexual queens, they found storage organs filled with sperm, a sign that the ants mated at least once.

Unlike sexual reproduction, asexual cloning allows individuals to pass on all their genes, not just half. Moreover, sexless individuals save a lot of time and energy by evading the dating game; they avoid exposure to sexually transmitted diseases, and endure catastrophes better - a single survivor can clone itself and establish a new population.

On paper, asexuality seems like a winning strategy. Sexless creatures pass on all their genes—as opposed to just half—and “you don’t have to spend huge amounts of energy going around and finding a mate and going through courtship and exposing yourself to disease,”…

One advantage of asexuality for colonizing ants is that just one individual, rather than two, can clone itself and establish a new population…

On the other hand, having sex gives any species the ability to adapt quickly, and react to changes in the environment and ecosystem.

Yet species overwhelmingly engage in the messy, costly business of sex because it provides the genetic variation species need to react quickly to environment and ecosystem changes, ...

Seems the fungus-farming ant might have it both ways after all, like fire ants and other species.

The ability to choose between sexual and asexual reproduction seems quite useful - and leads to several questions…

Beyond the most obvious environmental stressors, what else triggers these shifts in ant sexuality?

Are other species flipping back and forth too? Why?

What does it take for a species to develop the ability to reproduce asexually?

How does the asexual ability manifest in its early stages? Is there a loss of distinction in sexual differentiation?

What does it mean?




As an aside, "Ants discovered farming long before we did - they have been cultivating fungus gardens for an estimated 80 million years." …I can't think of ANY human industry that's lasted any significant period of time. I suspect the ants' farming industry survived for 80 million years because it's completely natural and thereby, sustainable.

I read somewhere that there is good evidence that protection against diseases and parasites passed on from parent to child is one of the incentives to develop sexual reproduction. When their genetics differ, it is harder for mothers germs to infect the child.

reply to post by Maslo

I read somewhere that there is good evidence that protection against diseases and parasites passed on from parent to child is one of the incentives to develop sexual reproduction.

True - it's not just fun it's useful too.

When their genetics differ, it is harder for mothers germs to infect the child.

Ahem. Works both ways - and sometimes, inheriting the disease with the resistance/adaptation is how evolution seems to work. Go figure.

...PS. Sorry it took me so long to reply! Still gardening and playing outside.