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Animals are programmed by their genes to act in a manner than most efficiently passes on these genes to subsequent generations, increasing the genes’ chance of survival. Thus, the “paradox of the lek” seemed to defy the very foundations of natural selection and genetics. A lek is a group of males with a very distinct hierarchy who gather together in competitive mating display as a large group. The females of the species almost always choose to mate only with the dominant males in the center of the lek, which should, theoretically, eliminate the diversity of the group and, therefore, the persistence of the act of preference itself. However, this choice is still seen in lekking species. This chapter studies lekking behavior in a variety of animals, such as manakins, the black grouse, antelopes, cichlids, and moor frogs by discussing many of the possible hypotheses for the selection of leks from scientists who have studied this peculiar behavior. Their findings are, to date, inconclusive, but point to such hypotheses lek size, competition among males, female mating bias, territoriality, networking, and environmental factors, as contributing to the persistence of lekking in animals.

Author: Kirby Kempe

Introduction

The wide variety of mating systems and display behaviors in the animal kingdom today represents species’ adaptation and co-adaptation to their environments. Mating behavior is determined both by ecological conditions and by differences in parental care and family organization. Mating behavior can be classified as monogamous or mating multiply, though there are multiple subsets of each broad classification. For example, in a polygynous species, one form of mating multiply, one male can mate with multiple females, whereas in a polyandrous species, one female mates with multiple males ( [link] ). Whenever individuals of one sex can mate with multiple individuals of the other sex, it follows from sex ratio arguments that some to many individuals of the multiple mating sex will not get to mate at all. Species that mate multiply, as opposed to monogamous species, are far more common in the animal kingdom and life-pairs are extremely rare. In fact, the most common system is one in which no bond is formed whatsoever and there is no care by either parent, known as promiscuity. However, even among only multiply-mating species, mating behavior varies widely. Natural selection has worked to favor elaborate courtship rituals and complex mating displays that underline the process of sexual selection , giving rise to species that spend much of their time and energy attracting a mate. Perhaps the most puzzling of these displays, known as a lek, is the large aggregation of displaying males that females interact with solely for the purpose of procreation (Kokko 1996).

Mating systems

Monogamy : Research suggests monogamy occurs when there is no potential for polygamy or for taking advantage of limited polygamy potential. It is estimated that over 90% of avian species are monogamous, but monogamy is very rare among mammals (Emlen et al. 1977). It is hypothesized that monogamy is advantageous when male territories are small and equal and the cost of mating is high, so polygynous females are at a disadvantage, and where male assistance is necessary to raise offspring so the male rears more successful offspring more by assisting one female than by mating multiply (Clutton-Brock 1989).

Polygyny : Polygyny occurs in situations where behavioral and/or environmental conditions cause females to clump together, where males either monopolize them directly or by hoarding resources and mate with the same group multiple times (Emlen et al. 1977, Clutton-Brock 1989). Polygyny is seen in many marsupials, carnivores, and rodents (Clutton-Brock 1989). Polygyny is most common when male home ranges overlap with those of several females as opposed to monogamous ranges overlapping with that of only one female (Clutton-Brock 1989).

Polyandry : Females can monopolize males if resources are congregated and able to monopolize or by defending and directly controlling males (Emlen et al. 1977).

While these are the main systemic classifications, some species alternate between variations of these while some mate in different arrangements altogether.

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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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