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Thursday, December 20, 2007

leks in animal world.


"Each organism takes birth on this earth to leave back its genes for a noble cause".
For this noble cause, the cost benefit ratio counts a lot. Mating systems, which describe the way in which individuals of both sexes obtain mates, vary widely in nature. Different animals follow different reproductive strategies out of which lekking is one eminent ethological approach.

(Courtship Lek,Sage Grouse)*

Lekking is a curious variation on promiscuous mating. "Lekking" is derived from Swedish origin, that describes a pattern of mating behavior seen only in a small number of birds around the world. In North America its chief practitioners are Greater and Lesser Prairie-Chickens, Sharp-tailed Grouse, Sage Grouse, and Buff-breasted Sandpipers. although this ethological pattern is very common in birds,its also seen in animals esp some lizards,iguanas, black bucks and deers.

(Buff-breasted sandpiper show off)*

During the mating season, the males of lekking species birds gather into small clusters of territories, called leks, or arenas. Each male defends a territory within the lek although the area may only be a few yards across. Thirty or more males can even gather at a large lek. They display with frantic intensity, sometimes oblivious to everything around them (though their intensity increases when females are present). The display varies from colour display of feathers, dancing patterns , singing(mating calls) to aggressive fights at times.

(Great Snipe lekking)*

(Growth of the horns in fallow deer males, display for lek)*

"Conflict and co-operation in competition over mates" forms the basis of lekking systems, which offers several examples of situations where males share common interests while competing for mates; lower ranking males will, e.g., all benefit from the top male not being able to monopolize matings. Also, kin selection could potentially affect optimal male behaviors and distributions.

(Lekking black buck males beginning a fight)*

(Lekking iguana male)*

Females visit the lek and wander among the displaying males as if comparing their virtues. Eventually a female accepts the advances of a particular male and mates with it. Usually only a few males out of all those present on the lek ever successfully mate. The female then lays its eggs in a nest that may be distant from the lek and that will never be visited by the chosen male.

(A Prairie Chicken in its lek with the display; bigger size:better display)*

The evolution of lekking is as interesting as the phenomenon itself. Factors determining degree of male clustering are still not well explained. A large number of different hypotheses have been suggested for explaining the distribution of males in lekking species. Some of the models involved in proposing the evolution of lekking are the female preference model, the hotspot model and the hotshot model.There may be social as well as ecological factors involved in determining male and female distribution patterns and hence the lekking patterns seen in the animal kingdom. Whatever may be the fact, but the evolution of lekking is to ensure the transfer of better, healthy and well competent genes to the next generation so that the "clan" continues in the future.

(* All pictures are uploaded from net in reference to the article.)

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