has been found in rodents, for example, you may keep the male copulatory activity based on renewed periodically go to females who have access until they are literally exhausted.
rule, reproductive activity involves somatic costs (fewer resources to increase in size) or survival (higher mortality), and this implies that a high current reproductive effort associated with a lower residual reproductive value. The existence of these costs may be the reason why a reduction in reproductive effort with the same partner. But this reduction may also be because the benefits may be derived from successive copulations will be dwindling.
Some have used the "Coolidge effect" to assess to what extent the reduction of reproductive activity in males was due to either of these two factors. It has done so by manipulating the access to females of male guppi (Fish million) and then evaluating its growth rate and reproductive behavior. A recent notice of that assessment. The
guppis or guppies (Poecilia reticulata ) are very well known in the world of aquariums. Males develop
courtship activity outrageous, matching courtship display permanently. The females choose males according to their color patterns and the characteristics of the courtship display. In most cases of male courtship is not successful, so that activity certainly ends up being costly, because the time devoted to it is not engaged in feeding, for example, and carries a significant energy expenditure.
The guppies are ovoviviparous. Females develop eggs inside until they are mature. The eggs hatch within the female and the fry out and fully developed. Males court females from that, three months of age are sexually mature. When a male "copula" or has access to a female, is placed next to adopting an "S" and use the gonopodium to throw packets of sperm. The female, although it has been fertilized and develop inside eggs, sperm can save part of it has launched the male to continue fertilizing her eggs with the sperm.
In the work to which I refer, males spent guppi four times longer time courting females than females known unknown. Made, therefore, greater efforts were renewed player when females had access, and also devoted less effort to feed. As a result, its growth rate was lower and reached the maximum size. Therefore, in guppis not only produces the Coolidge effect, but involves also evident somatic costs.
The reduction of reproductive effort of males to females and "known" can be beneficial for two reasons. On the one hand, if the male has already been rejected earlier by a female, no efforts will be made surely be useless to court again. On the other hand, if the male has recently copulated with a female, each successive copulation will result in a "performance" ("fitness") smaller, it is quite possible that already a number of fertilized oocytes of the female, the latter is consequence of the fact, already noted, the female can retain some of the spermatocytes of the male to fertilize their eggs later.
Thus, at least in this species, males lose interest in mating with females that they are "family" or which have mated and do not seem to be due to the costs incurred by it, but because is becoming less "performance" which is expected to try to obtain the same females. As seen, the renewed interest in courting new females indicates that the issue of costs does not constitute any limitation, because it shows perfectly willing to assume these costs with the new arrivals.
The reproductive biology of fish million has little to do with the human species, of course, but I'm sure many readers will have come down here thinking it may have very different fundamentals, but that the effect also applies Coolidge our species.