Under which of the following conditions is Semelparous reproduction (where organisms produces all its offspring in a single reproductive event) is most likely to be favoured? (A) Adult survival rate is low. (B) Adult survival rate is high. (C) Breeding is perennial. (D) Breeding is seasonal.

Adult survival rate being low makes the most sense since only would an organism want to reproduce as soon as it could and also all at once. At the same time, seasonal breeding also doesn't seem far off meaning an organism would only produce all its offspring in one particularly favourable season a d in it, it produces all of it.

This is from an entrance test for a research institute. I am confused between A and D. Reading about Semelparous reproduction didn't help. Please help me solve this one.

  • $\begingroup$ Please do not post text as images. It discriminates against blind and partially sighted people who use screen readers. And if you post this sort of homework question we require more evidence of effort than "reading about Semelparous reproduction didn't help". What did you read? Why didn't it help? $\endgroup$
    – David
    Jun 21, 2018 at 19:59
  • $\begingroup$ I feel like you're just out to hound me, David. You have been nothing short of uninviting until now. You told me about the images in my other question and I then wrote the question in the details. You could've just said remove the images as well. About the question, I did say that I was confused between A and D, both of which are almost correct and should tell you that I at least know what I'm talking about and am not just here to get the answer. In any case, I have complied to both your complaints. $\endgroup$
    – Fenil
    Jun 22, 2018 at 1:36
  • $\begingroup$ I know you're just following the rules and that my opinion doesn't matter to you but if you could just be a bit nicer with the tone, it would be more fun. If you see the comments on the first answer you'll even see that I discussed the answer with JayCkat who further cleared it up for me. $\endgroup$
    – Fenil
    Jun 22, 2018 at 1:41
  • $\begingroup$ I commented on this question unaware that the other question I had commented on was also from you. (Easy not to notice on the phone.) Otherwise I would have probably held off. It's not you I have it in for, it's MCQs in general. They are allowed here with certain provisos, but I feel that these must be strictly adhered to, as they are really not biological questions of general interest. $\endgroup$
    – David
    Jun 22, 2018 at 8:59
  • $\begingroup$ Duly noted. I disagree about MCQs though. I think well-formed MCQs are very good fuel for discussion and for checking concepts of school students/undergrads. $\endgroup$
    – Fenil
    Jun 22, 2018 at 9:13

1 Answer 1


All its offspring in a single reproduction event.

All and single are the key words here. Ie this organism produces all its offspring that it will ever have in one event.

When breeding is seasonal- however this does not exclude organisms that can produce several batches of offspring over several seasons. Animals like deer and bears. They reproduce seasonally but are able to live several seasons and thus are able to produce several batches of offspring.

For an organism that only reproduces once, the important factor is survival of the adult animal. If the adult animal does not live long (due to predators, climate), you could expect the animal to reproduce only once and die.

  • $\begingroup$ This was my thinking as well. But don't you think the predation pressure could be present on the younger forms as well, and not only adults? That adds a bit a of a twist. Although, for all intents and purposes, A seems to be the most appropriate answer. Thanks. $\endgroup$
    – Fenil
    Jun 21, 2018 at 2:28
  • $\begingroup$ Not really. Offspring are cheap. If there isn't so much pressure on adult form, the adults can continue to produce offspring. $\endgroup$
    – JayCkat
    Jun 21, 2018 at 4:41

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