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29ebJCyy | 5 years ago
> Why should an organism devote all its resources to one brood, or one breeding season? Much depends, again, on the risk of death by predation and other external causes—especially on how this risk changes over an animal’s lifetime. Suppose in some animal the juvenile stage is risky, but once you get to be an adult, you can expect to live for a while without being eaten. Then it makes sense for adults to reproduce more than once. That applies to fish and many mammals. If, on the other hand, the adult life stage is very risky, it might make more sense to “go for broke” as soon as you get to a stage where you can breed. Seasons also play a role. There might be a good season for laying eggs, or for hatching. That will determine a timetable within each year; perhaps it makes sense to mate in spring, or in winter. Then the question becomes: During how many years should you try to reproduce? Initially it might seem obvious that there is no harm in leaving it open, at least, that you will be around for another couple of years. You might make it through. Why fall apart in the meantime? But here the Williams argument returns, along with the need to think about these evolutionary questions by considering vast numbers of individuals and many generations. In the abstract, you would like to live and mate forever—at least from an evolutionary point of view. But who will leave more descendants, an organism which spends everything on one mating season, or a rival which spends less now in the hope of reproducing again later? If you spend less now to save something for later, that will do you no good if animals of your kind have little chance of making it to the next breeding season. In that case, it is better to put everything into one mating season, embracing all the options which give you an advantage now, even at the cost of breakdown once the season is done.
alikim|5 years ago