Criteria For Reproductive Success
The success of an organism is not only measured by the number of offspring left behind, but by the quality or probable fitness of the offspring: their reproductive fitness. Sexual selection increases the ability of organisms to differentiate one another at the species level: interspecies selection.
| “ | The grossest blunder in sexual preference, which we can conceive of an animal making, would be to mate with a species different from its own and with which hybrids are either infertile or, through the mixture of instincts and other attributes appropriate to different courses of life, at so serious a disadvantage as to leave no descendants. ... it is no conjecture that a discriminative mechanism exists, variations in which will be capable of giving rise to a similar discrimination within its own species, should such a discrimination become at any time advantageous. —Ronald Fisher, 1930 | ” |
The expansion of interspecies selection and intraspecies selection is a driving force behind species fission: the separation of a single contiguous species into multiple non-contiguous variants. Sexual preference creates a tendency towards assortative mating or homogamy, providing a system by which a group otherwise invaded by diverse genes is able to suppress their effects and diverge genetically.
| “ | Individuals in each region most readily attracted to or excited by mates of the type there favored, in contrast to possible mates of the opposite type, will, in fact, be the better represented in future generations, and both the discrimination and the preference will thereby be enhanced. It appears certainly possible that an evolution of sexual preference due to this cause would establish an effective isolation between two differentiated parts of a species, even when geographical and other factors were least favorable to such separation. —Ronald Fisher, 1930 | ” |
The general conditions of sexual discrimination appear to be (1) the acceptance of one mate precludes the effective acceptance of alternative mates, and (2) the rejection of an offer will be followed by other offers, either certainly, or at such high chance that the risk of non-occurrence will be smaller than the chance advantage to be gained by selecting a mate.
Read more about this topic: Sexual Selection
Famous quotes containing the words criteria, reproductive and/or success:
“There are ... two minimum conditions necessary and sufficient for the existence of a legal system. On the one hand those rules of behavior which are valid according to the system’s ultimate criteria of validity must be generally obeyed, and on the other hand, its rules of recognition specifying the criteria of legal validity and its rules of change and adjudication must be effectively accepted as common public standards of official behavior by its officials.”
—H.L.A. (Herbert Lionel Adolphus)
“In the nineteenth century ... explanations of who and what women were focused primarily on reproductive events—marriage, children, the empty nest, menopause. You could explain what was happening in a woman’s life, it was believed, if you knew where she was in this reproductive cycle.”
—Grace Baruch (20th century)
“The common idea that success spoils people by making them vain, egotistic, and self-complacent is erroneous; on the contrary, it makes them, for the most part, humble, tolerant, and kind. Failure makes people cruel and bitter.”
—W. Somerset Maugham (1874–1965)