I've answered a few questions with this process but I wanted to see if I could bounce/refine this off the communities more biologically adept members.

Basically, it goes like so:

As a means of reproduction occurring between 2 completely different species, I theorized that one specie could accomplish this if its means of reproduction consisted of injecting a 'female' (of any species) with retro-viral like structures that could fertilize an egg, pass on traits and potentially alter the female's physiology to support the pregnancy.

[technically I suppose the recipient doesn't even need be female]

For the sake of simplicity, I will refer to these retro-viral like gametes as RVS's

I know this is far fetched, simply because of the wild amount of things that need to go right: (FYI these aren't the post's questions)

  • How would these RVS's differentiate between an egg cell for fertilization vs a functional cell for mutation especially across the diverse spectrum of reproductive mechanics?
  • How would these RVS's know how to mutate cells to support the pregnancy
  • the amount of random chance needed for the inserted DNA not to break something important
  • the chances that the offspring could survive infancy
  • the effectiveness or severity of the immunological response

I postulate that one way this could work is that:

After picking a DNA containing host cell for fertilization, the RVS's release a chemical indicator telling the other RVS's to begin mutating other cells and/or enter an inert state (to be directed over the pregnancies term). The RVS's know what the RVS creature needs to mature and the host creature knows what its infant needs to mature. I assume the dormant RVS's could check for chemical indicators that the offspring's needs are being met (this sort of makes them more biologically like bacteria that produce retroviruses though).

Because this is happening on the bacterial/viral level, I think the possibility exists that there is enough random genetic mutation happening such that if pregnancy fails and the host lives it could try a completely different approach.

I expect the chances of this working to be slim. I expect that this would more likely result in the host dying during and after pregnancy.

I would justify the evolutional advantage of this trait as a means for a creature to be able to rapidly adapt and evolve to environments. Why evolve its own intelligence and oxygen breathing lungs when it can steal yours. Or as a means of ecological subjugation.

The said creature would likely target dominant lifeforms, ones that have advantageously adapted to an environment as they would have the necessary population levels to provide enough chances for successful offspring.

Anyways, my actual question which is semi opinionative, are there aspects I'm not considering? Are there factors that affect the plausibility more severely than I give them credit?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – James
    Commented Nov 10, 2017 at 18:58
  • $\begingroup$ There are egg paricites and brood paricites in real life. $\endgroup$
    – JDługosz
    Commented Nov 12, 2017 at 21:39

3 Answers 3


You describe Wolbachia.

These bacteria can infect many different types of organs, but are most notable for the infections of the testes and ovaries of their hosts. Wolbachia species are ubiquitous in mature eggs, but not mature sperm. Only infected females, therefore, pass the infection on to their offspring. Wolbachia bacteria maximize their spread by significantly altering the reproductive capabilities of their hosts:

  • They infect eggs (of many insect types).
  • The female that grows up from an infected egg will pass along the infection to her own progeny: vertical infection transmission.
  • If the egg is to become a male it dies; W wants females.
  • Some infected female hosts reproduce parthenogenetically because of the infection - no male needed. W wants females.
  • Huge overhaul of the body plan of the infected female is not necessary: finding food / evading predators / making more eggs! needs to stay intact.
  • If an adult male is infected with W it cannot reproduce - except with a female infected with W. Reproductive fitness of uninfected females is hampered. W wants females.
  • W infection can confer disease resistance and other superpowers to the host.
  • $\begingroup$ Fascinating, I had no idea there was a remote precedent. Not saying its spot on but it does parallel a lot of the mechanics. $\endgroup$
    – anon
    Commented Nov 7, 2017 at 19:16
  • $\begingroup$ You came so close with your scheme that the differences really are not significant. $\endgroup$
    – Willk
    Commented Nov 7, 2017 at 19:22
  • $\begingroup$ Well there is the aspect of passing traits from the RVS specie to the host. The biological changes needed to support those changes because its not as simple as a minor manipulation of a gender chromosome. $\endgroup$
    – anon
    Commented Nov 7, 2017 at 19:27
  • $\begingroup$ @anon - traits like virus resistance and insecticide resistance? $\endgroup$
    – Willk
    Commented Nov 8, 2017 at 16:05
  • $\begingroup$ That's a good foundation but its nothing like an extra set of arms or claws or mass. $\endgroup$
    – anon
    Commented Nov 8, 2017 at 17:21

You do not need retroviral activity the fertilize a gametes

The gamete (egg or sperm) has already moved from two copies of chromosomes to one copy. So you need a second copy of the chromosome.

Better Plan is to use retrovirus against one gamete and then introduce this to the other gamete.

Inerserting genetic information into a genome randomely is going to create problems (well with genetics on earth anyway. All bets are on alien system)

First you can destroy important information second if you insert more than a small amount of information the chromosomes will not longer match up and the organism will just die.

Finally. Really mixing genomes really doesn't work well in really life. this is mostly a science fiction thing. but you might want to look into the concept of instantaneous speciation through polyplody, though please avoid the sites that say this discredits evolution.

Also https://en.wikipedia.org/wiki/Bacterial_conjugation the transfer of dna between bacteria might be of interest to you

  • 1
    $\begingroup$ So what you are saying is it would be more successful if it hijacked a gamete and then waited for natural copulation with that gametes opposite? $\endgroup$
    – anon
    Commented Nov 7, 2017 at 19:22
  • 1
    $\begingroup$ That would be a better way of doing it. The bacteria @Will describes are mostly doing that. The ones that induce parthenogeneisis found a way around it. (P.S. your comment may be better than my answer) BTW imagine a bacteria // virus that infects both sexes and creates a new species ... there are issues but there are biological precidents $\endgroup$
    – P Chapman
    Commented Nov 7, 2017 at 19:24
  • $\begingroup$ This makes for an interesting inlet to tri gendered reproduction $\endgroup$
    – anon
    Commented Nov 7, 2017 at 19:29
  • $\begingroup$ So are you talking about paracites male, female, host (joking a bit). You might be interested in wheat which contains the complete genomes of several different grasses news.nationalgeographic.com/news/2014/07/… $\endgroup$
    – P Chapman
    Commented Nov 7, 2017 at 19:36
  • $\begingroup$ The tri-gender comment was a tangent towards other questions which have asked about more than 2 partners. For the purposes of this topic its purely bisexual (probably the most correct usage of that word). $\endgroup$
    – anon
    Commented Nov 7, 2017 at 19:47

The DNA and protein synthesis systems in a living cell are basically a chemical computer and storage medium. The only flaw I see is that the processing components are missing from a virus and it relies on its target cell having a certain set that it can hijack and use. As such, if you want this reproductive method to be completely universal it will need to be more like a bacterium than a virus, at least initially. That way it's guaranteed to have what it needs to run. Once established though it may well start creating viruses to hijack particular host cells and bend them to its will.

With that caveat, there's no reason you couldn't have a (very large probably) DNA segment that codes for a process that will grab the host's DNA, analyze it, figure out how their reproductive system works, and hijack it to produce whatever kind of offspring it sees fit (or, you know, build a reproductive system that's more to its own liking if the host's isn't suitable.) The only issue is that DNA processing is, at a wild guess, probably no faster than a 4KHz computer. Think 1950s monstrosity reading punched paper tape. You can make it massively parallel, but that only helps with certain kinds of problems. As such, an interesting twist would be for it to analyze the host's metabolism first so it can build itself a mass of neurons to do its processing at higher speeds.

Whether that mass of neurons would have sufficient programming to analyse the host nervous system (if any) and encourage it to feed and protect the spawn that are being created is up to you.

Do note that something this complex is rather unlikely to arise in nature as inter-species competition makes finding sufficient resources to develop such a system exceedingly difficult. Most likely it would be the result of genetic experimentation in a lab somewhere that managed to escape into the wild, or a hyper-advanced species that has been doing genetic engineering for so long that they have merged it into their regular bodily functions.


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