Gifting Body Parts For Sex: How Nursery Web Spiders Seduce a Mate

The differences in reproductive values of
sperm vs eggs, and the resulting conflicts of interest between males who want more sex,
and females who have had enough, have resulted in the evolution of some pretty extravagant
strategies for males to be reproductively successful. After all, if a female has enough sperm in
her storage organ she is probably not interested in receiving any more. And this is bad news for any guy who has yet
to make his own sperm deposit. So, what can he do to convince a lady that
his sperm might be worth an extra roll in the hay? Presents! Male nursery web spiders bring gifts to females,
the bigger and heavier, the better. These gifts can take diverse forms, from prey
items, to glandular secretions, water, specialized meals – or even parts of his own body! And these aren’t any cheap gifts. They are giving a female an expensive present
in exchange for sex. Well, most of the males. About 30% of the time, male nursery web spiders
provide females with dummy gifts – pieces of garbage, arthropod exoskeletons, or plants. These are made to look like the high-quality
gifts of their rivals. Basically, designer knockoffs. In addition to appearing authentic, they come
in several layers of wrapping. Females must take the time to unwrap them
before discovering their true quality, time in which the male might already have gotten
started. Since the cheating spiders are not spending
any time or energy in actually hunting and killing a ‘nice’ gift they have more time
for a higher number of copulation attempts, but with a lower level of sperm transfer. The good news is that since the cheating males
realize a lower level of sexual success, fewer of their cheating genes will be sustained
in future generations. The males giving legitimate gifts will always
be more reproductively successful, meaning that the balance of power stays with them. This is great news for jilted ladies. Hold out for the high-quality goods – bugs,
secretions, eight-legged back rubs. they will come your way eventually. Want to see more animal videos? Then check out this playlist from our friends
at The Dodo. Don’t forget to subscribe, and keep coming
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