Biological Research

Better Sex For Good Gifts

This is true for spiders, Danish and German researches find out

26.11.2013 | A male spider that gives its favoured female a nuptial gift is allowed to mate with her for a longer period of time and provide more sperm than a male without a gift.
If a male spider goes to the trouble of finding a good gift, wraps it up nicely in spider silk and offers it to a female he would like to mate, he has far better chances of fathering her offspring than if he skipped the present. This is shown in new research from Aarhus University's Spiderlab, where researchers studied what it means for female spiders to receive gifts. The male's nuptial gift consists of something delicious and edible, such as a fly, which he wraps up nicely in white silk prior to offering it to the female. He can then transfer sperm while she is eating the gift.
A male nursery web spider
Bild vergrößern
(© Gabriele Uhl)


A male nursery web spider | (Pisaura mirabilis) approaches a female spider with a gift.

If he remembers to bring a gift, he is allowed to provide her with more sperm, and the duration of the copulation is longer. Furthermore, the male has silky threads going to the gift from the silk glands at the rear of its abdomen. This enables the male to remain attached to the gift until it is eaten up.

When a male has mated with a female spider, the sperm is stored in a special organ under the rear part of the female's body, from which it can be released when the female has eggs that need to be fertilised. The researchers discovered that the female stores more sperm in this organ if the male has brought a gift, and he is therefore more likely to be the father of her offspring. It can thus be demonstrated that the female is capable of regulating how much sperm she stores, enabling her to favour males that provide her with culinary gifts.

The female presumably prefers sperm from the gift bearer because it shows that he is resourceful and good at hunting and catching food. If these are good hereditary traits, the female can transfer the qualities to her offspring by favouring the male. The female spider thus selects sperm from the males she prefers, and has the benefit of passing on their good characteristics to her male offspring.

The study was made on the Pisaura mirabilis species, or nursery web spider. Responsible for the research are Maria J. Albo and Trine Bilde, Department of Bioscience at Aarhus University, and Prof. Gabriele Uhl, University of Greifswald.   (© Aarhus University, AcademiaNet)
Anne-Mette Siem

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