https://press.uni-mainz.de/determining-sex-in-ants/
somehow a male ant has one set of chromosomes while the female ant has two sets of chromosomes. So a male ant sperm must contain enough information to make a complete male? Then when they mate with the female of the other species, the females egg actually gets blanked out so to speak, containing none of the females own genetic material. Then the male sperm fertilizes the egg with one set of chromosomes producing a male offspring that is a clone?
Having genetic differences between males and females is mostly a bird and mammal thing, at least among vertebrates.
(It’s possible that this was just a Greek quirk and never made it to Palestine, I suppose.)
This ability of the female to give birth to "multiple species" seems to me best understood as the two "species" not having yet actually become distinct, since the only meaningful definition of speciation is when two sub-populations of a species have genetically drifted so far apart that they can no longer successfully interbreed and produce fertile young.
During the process of speciation (one species splitting into two) there are going to be various messy half-way stages such as lions and tigers still able to interbreed and so not fully speciated (even if well along, and not going to typically interbreed), horses and donkeys still able to interbreed but producing infertile young (mules), and these ants in this strange state where interbreeding apparently only results in males. It would be cool to be able to speed up the evolutionary timescale to see the process happen, but what we have here is like a still frame from a movie.
https://www.sciencedirect.com/science/article/pii/S003257911...
In normal ants, the queen can produce haploid (single set of chromosomes) unfertilized eggs that hatch into males. Normal ant males are haploid. They don't have a father, they can not have sons (but the do have a grandfather, and their daughters will make them grandsons). When the ant queen decides to produce sons, she will make haploid eggs via meiosis as normal, and just won't fertilize them with male sperm.
Ants don't have sex chromosomes. An individual with a single set of chromosomes (haploid) is a male, an individual with double set of chromosomes (diploid) is a female. Ant males are almost like sperm cells that grew into multicellular organisms.
https://en.wikipedia.org/wiki/Haplodiploidy
Now, a Messor ibericus queen can produce eggs with her own genetic material removed, and fertilize these with the single set of chromosomes from a Messor structor male. (It will still have the mitochondria and mitochondrial DNA from the queen.) And because the male only has a single set of chromosomes, the sperm and the resulting offspring has an identical single copy of the father's genetic material (except the mitochondria that came from the mother). So the son is a clone of the father (except for mitochondria).
The queen can also mate with males of her own species, contributing half of her own chromosomes to combine with the full single set of the male chromosomes, to produce to-be-queen female offspring. Here we have the normal genetic recombination (though only on the mother's side) to keep the evolutionary benefits of the variation from sexual reproduction.
Your last sentence correctly points out the frailty of our definition of "species". However, this is not the only time our data has confounded our artificial, if often useful, definition of species boundaries.
I wonder what are the most visually, or structurally, or genetically, different animals that can still interbreed. Things like lions & tigers, polar bears & grizzlies, and zebras & horses, come to mind ... what else ?!
For example, American bison and domesticated cattle can interbreed to produce fertile female beefalos, but the males are sterile. Are domesticated cattle the same species as buffalo?
Then there's ring species: populations of animals where population A can interbreed with populations B and D, but not with C, but C can interbreed with B and D. (often the rings are larger than that). For example, the genus Ensatina salamanders here in California can interbreed with neighboring populations as you go around the mountains, but if you drove one from one side of the central valley to the other it couldn't interbreed. We've mostly decided in that case to call them a bunch of different species, but it's a weird case.
Shit gets even weirder when you leave the animal kingdom. All varieties of pepper will cross pollinate. Bacteria just sort of spread their genetic material to anything that's nearby. Don't even get me started on the absurdity of declaring all the asexually reproducing organisms as being single species individuals.
Basically, a species is a group of animals that has enough of the following characteristics that biologists can agree they're sufficiently different things:
1) They appear distinct from other things
2) They exclusively select mates from their group
3) They exclusively produce fertile offspring with their group
4) They occupy a distinct niche in their ecosystem
5) They are more genetically similar to other members of their group than to other things we consider distinct species
6) Their common ancestor with another group we identify as a species is extinct and considered a different species
7) They really seem like they should be a speciesQueens don't actually mate to produce male offspring.
Females are Diploid: They are created from a fertilized egg. They have two sets of chromosomes - one set from the mother (the queen) and one from the father's sperm, which the queen releases from the spermatheca when she wants a female.
Males are Haploid: They are created from an unfertilized egg. They have only one set of chromosomes from the queen located in the nucleas of the egg. The queen does not release the male's sperm when she wants a male offspring. They have no father. They hatch from an egg that contains only the mother's genetic material, meaning they are essentially a haploid (single chromosome set) version of the queen.
The M. ibiricus queen produces 2 kinds of offspring with the M. structor:
Sterile Female Hybrid Workers: These are produced in the standard way. The queen lays an egg (containing her genes) and fertilizes it with the sperm from the M. structor male. The resulting worker has DNA from both parents. It's a true hybrid. There is no "dominance"; it's a merger of two different species' DNA.
Fertile Male M.structor Clones: This is where things get really bizzare.
Remember that in the normal case:
- The queen does not use a male's sperm to produce male offspring.
- Joining both DNA always results in a female (males do not have two sets of chromosomes)
There can only be one conclusion. The queen creates this special clone from the male's DNA only, probably by somehow purging her DNA from the nucleus of her egg.
https://www.newyorker.com/magazine/2020/05/25/where-do-eels-...
Also: the configuration and function of sex chromosomes is not consistent even within mammals. There are a number of species - primarily rodents - with unusual sex-determining systems, like species with XX/X0 (i.e. where males have an unpaired X chromosome) or even X0/X0.
I hadn't really considered the definition of asexually reproducing species - it seems that things are much more clear cut for ones that sexually reproduce since then we can use the more clear cut "point of no return" definition.
I suppose in cases like beefalos and mules, or these ring species, this "point of no return" comes down to is there any path for to the DNA of these divergent animals to recombine, so a fertile female beefalo (or the occasional fertile female mule) still provides that chance.
It seems that in general it's rare for widely divergent animals like zebras and horses to interbreed in the wild, but apparently western wolf-coyote hybrids are not that uncommon, so it's more than just a theoretical possibility. Who knows, maybe global warming will force polar bears to adapt to warmer climates and increasingly interbreed with grizzlies.
The interesting part is whether M. ibericus queens do actively remove their own genetic from eggs fertilized with builder sperm. Why would they do this?
M. ibericus queens produce ibericus×structor hybrids as infertile female worker ants.
M. ibericus queens produce structor males, so future queens can keep producing the hybrid worker ants.
My guess is, maybe there is some benefit having the workers to be hybrids and not pure ibericus ("hybrid vigor" [1]). So it's worth the effort of keeping the structor males along, to be able to produce the hybrid workers. But I think the pure ibericus genes in the line of queens are in control.
In reality, we first categorized life into species because they either looked different or we found them exclusively in different places, and only centuries later did we attempt to figure out exactly why and how this was the case and reverse engineer some sensible definition onto the pre-existing categories, but it turns out there is no single definition that works universally and has zero exceptions. It's frustrating if you're a language pedant who likes clarity, but a lot of categories and definitions are like this.
Evolution seems more like building a tree where mostly all you can do is ascend the tree and add finer detail, leaving the trunk and branches (our evolutionary history) in place. It seems unlikely that, say, vertebrates are in the future going to "undo" the major evolutionary developments of the past and lose their skeleton, body symmetry, number of limbs, lungs, alimentary canal, nervous system, brain, etc. We see things like these developing in the evolutionary tree and mostly staying in place once created. Sure some fins turned to limbs, some gills to ears, but once things like that happened they seem to stay in place.
I wonder what evolution would look like if we could see it sped up from the origin of life to billions of years into the future? A building up of complexity to begin with, but those major branches of the evolutionary tree remaining pretty stable it would seem. Continual ongoing change, but of smaller and smaller scope, perhaps - building on what came before.
This confuses me too.
Did the queen once mate with one of these males and save the sperm for two years? Or are the queens somehow born with a copy of the genetic material.
Or does the old queen produce one, which mates with the new queen, and then dies off. And the new queen is able to hold onto that sperm for years (forever?). And they only produce a handful of males for this purpose?
Also why is it so difficult to have males in lab conditions?
Basically, your sex drive is the main search optimization :p
Edit: This is essentially how genetic algorithms in computer science work. They’re often remarkably effective at finding good solutions without needing brute force.
There's lots of processes that favor certain patterns over others, only considering the biochemistry of the cell, not even the fitness of the animal.
I didn't know this. I suspect this evolved because some amino acids are more useful than others, and increasing the probability of encoding for them was beneficial.
Try looking at whale skeletons over time. What isn't beneficial gets undone.
https://en.wikipedia.org/wiki/Recurrent_laryngeal_nerve#Evid...
In some though not all such species, there are no known male examples _at all_ (though in reptiles some forms of parthenogenesis can produce males).
Any early branch can infinitely on that confined branch. It means the billions of other possible branches may never be explored even given infinite time.
Counter would be the evolutionary fill theory where any branch can become any other branch given an environment.
https://www.biblegateway.com/passage/?search=Leviticus%2011:...
Similarly, beneficial and complex traits, like eyes, can "regress" if nothing selects against that trait. Plenty of species have lost their sight, making them less generally fit for many environments, because in a certain place and time those species could reproduce even without perfect vision, or just as the result of genetic drift.
Just wanted to add this, i see where the formulation is useful as a figure of speech.
In sexual reproduction the offspring has 50% of its genetic material from both parents. In sperm parasitism the offspring is 100% related to the male and the female’s genetic material has been destroyed.
These inbericus females are allowing the messor male line to reproduce by sperm parisitism to maintain a domesticated messor line that they can then later sexually reproduce with to create hybrid worker ants.
And there's junk DNA where mutations can accumulate over time without being subject to selection before getting enabled at random to see if they give you an advantage.
I think both the amount of junk DNA and the mutation rate are themselves subject to evolution for the best trade-off.
This isn’t even the only weird idea that people used to have about reproduction; there’s also stuff like https://en.wikipedia.org/wiki/Barnacle_goose_myth
(From the above: “Bible Gateway is currently unavailable to consumers in the United Kingdom and European Union due to technical issues.” I am now very curious just which EU regulation the bible website was worried about.)
Climate change produces a changed environment. It actually drives more evolution to adapt to that changed environment.
Even very sudden changes such as some that caused mass extinctions, it just changed the direction of evolution. The only species that stopped evolving were those that went extinct. No more dinosaurs (bar birds) but lots more mammals.
I find it interesting that this has not led to all the clones knocked out by diseases, as happens to eg our banana plantations.
Who is doing the removing at fertilization is interesting mostly in a mechanical sense. The mechanisms that worked against it are being suppressed or selected out entirely.
It sure is an interesting case that one ant species is having another species promote their males if one looks at it from a gene perspective. A very weird case of symbiosis.