The many theories on the evolution of secondary sexual characters, are an evolution in their own right. The purpose of this paper is to analyse the evolution of the research and hypotheses on this subject. How did each come about and lead to another, which was proven and find the answer to the question:

How do females benefit from choosing a male with an enhanced morphological feature?

Sexual selection is a corollary of natural selection and the two processes work in the same manner. Natural and sexual selection often create different selection pressures: natural selection results in traits that enhance reproduction and survival, where as sexual selection results in traits that enhance reproductive success, but at the expense of survival (Ghiselin(1969) of Darwin in Birkenhead & Moller 1991).

Sexual selection occurs when the members of one sex mate disproportionately with members of the opposite sex on the basis of seco

Andersson M. & Iwasa Y. (1996) Sexual Selection. TREE vol11 p53.

Jennions. M.D. (1993)Female choice in Birds and the cost of big tails. TREE vol8 p230.

The train is a classic example of sexual selection, as with many species where the male is brightly coloured, it is employed to attract females (Hill 1991). Marion Petrie et al. (1991) undertook many experiments to prove that male peacocks, Pavo cristatus, with longer tails enjoy more successful copulation's in a season. They investigated two hypothesis for the evolution of an extravagant morphological feature i.e. the peacocks train: (1) the train could have evolved because of its importance in competition between males, or (2) females could prefer males with more elaborate trains, either because the train indicates something about the male that is important to the female, or because females have developed an arbitrary preference for males possessing the character. Both hypotheses predict that variance in mating success would be accounted for by variance in train morphology (Petrie et al. 1991). The experiment results showed that there is non-random mating in peafowl, that a large part of the variance in mating success can be attributed to variance in train morphology and that females choose to mate with those males that have the most elaborate trains of those sampled (Petrie et al. 1991).

Brookes M. & Pomiankowski A. (1994) Symmetry is in the eye of the beholder. TREE vol 9 no 6 p201.

Mason,G. (1993) Are birds with long tails sexier? New Scientist v138 (3 April) p17.

Keller L. & Krieger M.J.B. (1996) Mating success of male birds. NATURE vol 380.

Some common words found in the essay are:
Birkenhead Moller, Hamilton Zuk, Asymmetry Fluctuating, Krebs Davies, Marion Petrie, Malte Andersson, Enquist Arak, , Cambridge University, Blamford Thomas, sexual selection, moller 1991, birkenhead moller 1991, birkenhead moller, krebs davies, mating success, krebs davies 1993, davies 1993, male quality, et al, al 1991, female choice, et al 1991, petrie et al, fisher krebs davies,
Approximate Word count = 2954
Approximate Pages = 12 (250 words per page double spaced)