Courtship, or the process by which an individual selects and fights for his or her partner to reproduce with, is one of the most remarkable processes in the ecological world. Though the trait ranges widely, from performing an eloquent dance by flailing the bluest of feet (Blue-Footed Bobbies) to constructing elaborate nests of seduction (Bowery Bird), males work tirelessly to advertise their strength, overall health, and mating desirability. In many cases, these displays are energetically costly and risky, leading to the depletion of important resources and a risk of predation. Nonetheless, for reproducing animals, the importance of selecting a quality mate, cannot be overstated, for the decision will affect the individual’s percentage of viable offspring and the preservation of his or her genes.
Working under the theory of sexual selection, proposed by Charles Darwin, who stated that certain evolutionary adaptations are solely designed to help individuals outcompete others for mates, scientists have developed several different modes of thinking about the evolution of preference and trait.
The good gene model of sexual selection, states that females tend to choose mates that display honest indicators of the male’s ability to pass on genes that will lead to greater future survival and reproductive success of her offspring. The brightness of a bird’s feathers, for example, may reflect foraging ability, because an increase in the consumption of carotenoids (organic pigments in many fruits and vegetables) leads to a less dull color. Since foraging ability is under genetic control, females that choose a male that is an efficient forager will tend to produce offspring that are also efficient foragers.
The Handicap Hypothesis states that some sexual adornments are harmful to males but have become attractive because they signal to females a male’s ability to cope with them. The bright colors of a bird, for example, make them extremely vulnerable to prey. The bright feathers may therefore be an honest indicator of being able to survive despite the handicap.
Another hypothesis, called Sensory-Bias, states that males have evolved traits that attract the attention of females, through certain colors, sounds, and shapes that are pleasing to a their sensory system. Female guppies, for example, tend to be more attracted to males that sport large orange spots, which may be linked to an innate sensory bias of food detection.
Lastly, Runaway Selection Hypothesis states that the female preference for a trait and the trait itself may be linked overtime – a positive feedback mechanism that results in elaborate structures, like the feathers of a peacock, which may lead males to endure costs that outweigh the benefits.
These hypotheses help us better understand some of the most wondrous behaviors and traits observable in nature and appreciate the exhausting efforts animals take to find a mate.