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Zoology: Is interspecific sex common in wild life?

  1. Jul 21, 2017 #1


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    I have seen some examples of interspecies sex,



    So, my question is: is there any explanation to the interspecies sex in wild life?

    Thank you for your time.

  2. jcsd
  3. Jul 21, 2017 #2

    jim mcnamara

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    Some of the mating pheromones or displays animals give are similar. Actual reproductive isolation of many species is at the genetic level. Example: horse x jackass gives infertile mules. Birds are more likely to have varying displays and calls.

    In terms of individual fitness and survival of the species it is almost always not adaptive to mate outside a species. There are lots of hybrid plants and animals that can reproduce asexually. Exception: Wikipedia on parthenogensis:
    This thread is almost guaranteed to go way off topic. When it does that is the end of it.
    Last edited: Jul 21, 2017
  4. Jul 21, 2017 #3


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    I think the explanation would be that the male sex drive is strong (its usually the males forcing the issue in these cases I would expect) and not always restricted to conspecifics (members of the same species). Or more concisely, amped-up and mis-directed sex drive.
    I think @jim mcnamara has correctly pointed out that in some species displays and other signals could provide a restriction of sexual activity to the same species.

    I had an ecology prof. once whose wife studied animal homosexuality.
    This is similarly not reproductive and not adaptive, but it occurs.
    Her interpretation of it was that it was like practice for the real thing (however, I don't recall if it was more common among young animals or not).
  5. Jul 21, 2017 #4

    jim mcnamara

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    @BillTre - There are fish species that change sex as they age; I do not know where they fit -- in this kind of discussion.
  6. Jul 21, 2017 #5


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    Here's an interesting article about cute (?) otters:

    I don't think that pheromones alone can be pointed out as the main or single reason. Testosterone probably plays a similar, if not more important role. Some animals like elephants or deer have a really high level at times. And why should animal behavior in general be any different than the behavior of a single species? The question "is it common" is rather vague. What is common? It occurs. And even our cats and dogs show sometimes signs of it. Common is already a non-scientific assessment.
  7. Jul 21, 2017 #6


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    @jim mcnamara, thats an interesting question.
    Some fish change sex based on some schedule, some when the social opportunity (the alpha male place) opens up for them locally.

    Alpha males in some territorial cichlid species will often keep beta males repressed through territorial aggression (affects certain GnRH containing hypothalamic brain regions, which in turn affect pituitary, sexual organs, and behavior, which can affect the brain and hypothalamus).
    Something like this may be going on during other sex change, but I don't know.
    I have no idea how this fits in with animal reproductive events described above, but reproductive behaviors will probably involves some of the same elements.

    WRT @fresh_42's post, when it comes to reproduction within species there is a lot of common behavior that is not up to (nice) human standards.
    Many invertebrates impregnate the female (or hermaphordite) by jamming its penis (or whatever it might be called) through the female/hemaphrodites body wall to get the sperm in rather than using the apparently more pleasant vaginal entry site.

    When I was a kid we had a pond in our back yard and in the spring I often saw male American toads clutching dead females underwater in their mating embrace. I don't think this is uncommon behavior.

    I guess, in the long run, if a set of behaviors result in reproduction and numerous offspring, it is adaptive, though not always pleasant.
    If the physiological mechanisms underlying those behaviors lead to mating with the "wrong" species or "wrong" sex occasionally, but still result in reproduction in other cases, those mechanisms will still be adaptive.
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