The role of evolution in mating behavior of lekking species  (Page 5/11)

The evidence of female preference was found in the distance the female manakins traveled in order to mate. If females had no preference of lek, they could be expected to mate at the lek closest to their current location in order to minimize search costs. However, the results of this study found that only 33% of females mated at the nearest lek and most mated at leks located significant distances from the lek nearest to their nest (Durães et al. 2009). This shows that females did, in fact, have a preference for where they mated, and the preference seemed to be based on size of the lek. Females that passed up the nearest lek to mate elsewhere were located close to a lek that was significantly smaller than the one at which they chose to mate. In other words, the lek closest to the female’s nest was very small so the females chose to travel a greater distance in order to mate at a larger lek. However, females that were nesting in close proximity to an average-sized lek were no more likely to visit a larger lek than the one nearest them.

In determining whether heterozygosity was a factor in the mating choices of females, the researchers found that the male manakins increased vocal displaying on larger leks but that the rate of vocalization did not reflect heterozygosity of the male or of his offspring (Durães et al. 2009). However, the males that females chose to mate with did vocalize more than non-siring males on a given lek. This indicates that the investment of vocalization is effective in increase a male’s probability of producing offspring and that male success is limited by the extent to which they are able to increase display (Durães et al. 2009).

The overall conclusion of the study supports a subset of the preference model called the “best-of-n” hypothesis (Durães et al. 2009). The “best-of-n” males is a model describing female mating behavior that describes female behavior as choosing the best of n males she encounters (Janetos 1979). This model is unique in that it requires the assumption that females have a memory capacity, and the capacity may be measured by the size of n . Additionally, in the case of leks, a female might encounter the first of n males on one lek and the last in another lek. If the best of n is in the first lek, the model requires that the female is able to return to the first lek and mate with that organism (Janetos 1979). The results of this study support the best-of- n­ model over strict female preference because while female preference is a main condition for determining which organism is “best,” the females who were able to encounter n males at a nearby lek visited only that lek, whereas females who were nesting close to a lek of smaller size than n were forced to travel until they came upon another lek in which to find the best. Strict female preference, on the other hand, indicates that the act of being at a larger lek benefits males.