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The 1948 experiments inferred reproductive success based on the number of adults living by the end of the trial. In reality, many factors were left out of the equation when calculating reproductive success as a function of the number of mates, which had the ability to completely dislodge the accuracy behind Bateman's results.
[36] [page needed] The two-fold reproductive disadvantage assumes that males contribute only genes to their offspring and sexual females spend half their reproductive potential on sons. [ 35 ] [ page needed ] Thus, in this formulation, the principal cost of sex is that males and females must successfully copulate , which almost always involves ...
Louise Joy Brown (born 25 July 1978) is an English woman who was the first human to have been born after conception by in vitro fertilisation experiment (IVF). Her birth, following a procedure pioneered in Britain, has been lauded among "the most remarkable medical breakthroughs of the 20th Century". [1] [2] [3] [4]
Human reproductive ecology is a subfield in evolutionary biology that is concerned with human reproductive processes and responses to ecological variables. [1] It is based in the natural and social sciences , and is based on theory and models deriving from human and animal biology, evolutionary theory , and ecology .
Ernst Mayr recognised the key importance of reproductive isolation for speciation in his Systematics and the Origin of Species (1942). [44] W. D. Hamilton conceived of kin selection in 1964. [45] This synthesis cemented natural selection as the foundation of evolutionary theory, where it remains today.
Sexual selection creates colourful differences between sexes in Goldie's bird-of-paradise.Male above; female below. Painting by John Gerrard Keulemans.. Sexual selection is a mechanism of evolution in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
Pheromones play an important role in the sexual isolation of insect species. [13] These compounds serve to identify individuals of the same species and of the same or different sex. Evaporated molecules of volatile pheromones can serve as a wide-reaching chemical signal. In other cases, pheromones may be detected only at a short distance or by ...
Eventually, if reproductive isolation is achieved, it may lead to a separate species. However, reproductive isolation between hybrids and their parents is particularly difficult to achieve and thus hybrid speciation is considered an extremely rare event. The Mariana mallard is thought to have arisen from hybrid speciation. [citation needed]