Sperm competition story

These delicate creatures have evolved extreme features to help manipulate the opposite sex. Female green-veined white butterflies Pieris napi are polyandrous, they mate with many males. A male green-veined white butterfly is able to sense whether a female has already mated or whether she is a virgin. This overload of sperm helps ensure that she does not find another mate too quickly. It has a downside though, as it takes a male a lot of energy to produce such a large deposit.

Sperm competition , a special form of mating competition that occurs in sexual species when females accept multiple mating partners over a relatively short period of time. The potential for overlap between the sperm of different males within the female has resulted in a diversity of behavioral adaptations and bizarre strategies for maximizing paternity. Sperm competition is thought to be the primary reason why males offer nuptial gifts such as food to females or allow females to cannibalize them. Such nuptial gifts are best thought of as mating effort that is, effort directed at increasing the number of offspring a male sires , because they are usually not available at the time of birth or hatching to benefit the offspring sired by the male presenting the gift. Sperm competition favours the evolution of paternity guards or mechanisms that reduce the impact of the mating efforts of competitors. In many animals , sperm competition results in mate-guarding behaviour, whereby males remain near the female following mating.

Sperm gets ejected from the penis, enters the vagina, and swims up the reproductive tract until they reach the egg to fertilize it. Barely years ago, it was considered a major scientific breakthrough when scientists came up with the idea that a fully formed, tiny human inhabited the head of each sperm — totally debunked and untrue. Fortunately, as the human body has evolved over thousands of years to maximize fertility potential, so has our scientific understanding about sperm. But many of us still believe some pretty unscientific, long-standing sperm myths. Here are twelve of the most common ones.

This week, I want to look at recent discoveries in one of my favorite subjects — sex. Discoveries that reveal surprising male subtlety. Discoveries that could, perhaps, have implications for how we approach in vitro fertilization I.