Fri, Dec 18, 2015
Biting your partner’s nose - a winner for birds, not always for humans.
Some men are naturally handsome, attracting women with little difficulty. But most have to rely on their wits, charm and the occasional bit of clever seduction to find a partner. And things are pretty similar in the animal kingdom.
Males produce millions of sperm so have the potential to father many offspring. But females produce relatively few eggs so have to be choosy about whom they mate with. If a male chooses a dud female there are few repercussions as he can quickly move onto another female, but if a female chooses a dud male it can be disastrous. For example, an elephant has a gap of around five years between offspring due to long gestation and weaning periods. That’s a long time to wait to choose a better mate.
As a result, it’s usually the males who compete over females via an evolutionary process termed sexual selection. For this, individuals produce traits such as ornate plumage that have no survival benefit. They have evolved purely to increase mating success.
Here’s the animal kingdom’s code for attracting members of the opposite sex and upping their game in the sexual selection competition.
Females are commonly attracted to males who have the largest, brightest, and boldest traits. The peacock is the perfect example of everything that is sexy to a peahen. He has bright and bold blue/green colouration combined with a very long tail. But why are traits like this attractive to the females?
The handicap hypothesis suggests that if a male can survive despite having a handicap such as a long tail, which would hinder escape from a predator, he must be a fit male and possess good genes which would be beneficial to any offspring. Indeed, it has been shown that male peacocks with fewer eyespots have lower success with the females, and also have a weaker immune system.
Apart from a visual attraction, females can also be attracted to males acoustically. Again, females generally prefer males with longer, louder and more complex vocalisations, possibly as these advertise the stamina of the males. Typical serenades come from bird or whale song, amphibian vocalisations and invertebrate chirps. But certain fish known as gymnotoids have also been found to attract mates with an electric “song”, and mice have been found to serenade mates with an ultrasonic song: apparently, the males break into song when they sense female urine.
Many organisms build structures to attract members of the opposite sex such as the intricate nests constructed by weaver birds. But, perhaps the best creations are built by bower birds. These ground-dwelling birds build various constructions depending on their specific species. Some build maypole-like structures while others create an avenue or platform on which they strut their stuff.
The bowers are usually highly decorated with ornaments such as rocks, flowers and berries, thought to allow the males to present themselves in the best way. Bowers have even been found decorated with brightly coloured plastic pegs, drinking straws and crisp packets, often stolen from the bowers of other males. The females check out the bowers then choose their mate, usually based on the best structure with the most objects.
Gifts are often seen as a good way of attracting a mate, and flowers, chocolates and jewellery are often replaced in the animal kingdom by nesting material, food items and pond weed, thought to advertise the attentiveness of the males. Some male spiders such as the Paratrechalea ornata offer their females prey wrapped in silk. The females often choose the males based on the size of this nuptial gift. Once the females start feasting, the male starts mating with her. Great crested grebes, meanwhile, form an elaborate courtship dance which culminates in the pair offering each other pond weed to build their nest with.
However, the male praying mantis offers the ultimate gift – himself. In this form of sexual cannibalism, the female devours the male during or after mating, for nourishment. How does this benefit the male? In evolutionary terms, an organism’s aim is to produce offspring and pass on its genes. So usually the the male has done his job once he has copulated with the female. But if he can help the offspring by feeding their mother, this will give them the best possible start in life, ensuring his genes survive.
There are lots of cheating strategies in the animal kingdom and for one species of bird, a method is to pretend to be a member of the opposite sex. The ruff is a bird that forms “leks”, where males aggregate to compete and display to females, rather like a nightclub. Females choose the males for one thing only, so the males provide no parental role.
The males usually strut their stuff for the females, and the most impressive males win. But there are also satellite males who hang around the edge of the “dancefloor” and grab a sneaky mating wherever possible. The most cunning mating strategy comes from the males who look like females and dupe the real females into spending time with them, then grab a sneaky mating whenever they can.
This article does not necessarily reflect the opinion of The African Exponent and its owners. Image Credit: Shutterstock. This article was originally published on The Conversation. Read the original article.
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