The role of evolution in mating behavior of lekking species  (Page 4/11)

Support

The manakin

Support for the preference hypothesis as an explanation for lek formation has come from studies on a very diverse array of species, from mammals such as the topi antelope to amphibians such as moor frogs. A study conducted by researchers at the University of Missouri-St. Louis followed blue-crowned manakins ( Lepidothrix coronata ) at a site in Ecuador to monitor the behavior of the organisms and determine patterns between and within leks (Durães et al. 2009). Part of the preference hypothesis proposes that females choose mates based on the size of their lek and that the females strongly prefer mating with males on larger leks. The study established male to female ratio between leks as an accurate indicator of this aspect of the hypothesis for a high ratio of females to males at larger leks would indicate that the females either actively or passively chose to mate with males on larger leks.

Support for the preference hypothesis as an explanation for lek formation has come from studies on a very diverse array of species, from mammals such as the topi antelope to amphibians such as moor frogs. A study conducted by researchers at the University of Missouri-St. Louis followed blue-crowned manakins ( Lepidothrix coronata ) at a site in Ecuador to monitor the behavior of the organisms and determine patterns between and within leks (Durães et al. 2009). Part of the preference hypothesis proposes that females choose mates based on the size of their lek and that the females strongly prefer mating with males on larger leks. The study established male to female ratio between leks as an accurate indicator of this aspect of the hypothesis for a high ratio of females to males at larger leks would indicate that the females either actively or passively chose to mate with males on larger leks.

The study also used relationships within leks to test the hypothesis that females choose mates that will maximize heterozygosity of their offspring. The theory of heterozygosity stems from the fact that sexual reproduction is costly because it carries with it the potential of accumulating in the offspring the parents’ inferior recessive alleles (Brown 1997). If females were able to choose mates to increase heterozygosity, this would decrease the chance of their offspring suffering from recessive homozygosity. Another benefit of heterozygosity is that it diversifies the genes of the offspring, increasing potential for adaptation to the environment, should it change. Thus, studies have shown that heterozygous males tend to have progeny that are more successful than the average in a fluctuating environment. Studies across many species have determined heterozygosity to be advantageous in areas such as pathogen resistance, growth rate, and developmental stability (Brown 1997). Thus, the University of Missouri-St. Louis study also controlled for among-lek variations and looked at mate choices within individual leks to determine whether females chose mates that were able to maximize heterozygosity in progeny. The study used vocal signaling as an indicator of heterozygosity, as it is costly and easily accessible as an honest signal to females (Durães et al. 2009). The quantifiable objective of this party of the study, then, was the correlation between vocal display and fitness in number of offspring, with the predation that more vocal males will produce more offspring because vocalizing is an honest indicator of heterozygosity (Durães et al. 2009).