A nuptial gift is a material presentation to a recipient by a donor during or in relation to sexual intercourse, other than gametes, which increases the reproductive fitness of the donor. Such a gift will usually improve the fitness of the recipient as well, though they can also be neutral or costly. Males may relinquish body parts, produce glandular secretions, or share prey or other food to gain fitness benefits, a process of natural and sexual selection. The study of nuptial gifting links sexual selection, nutritional ecology, and life history theory.
Different types of gifts Nuptial gifts are usually edible tokens: nutrition for the recipient. Many species of birds, insects, and spiders engage in courtship feeding: the gift of a food item from a male to a female just prior to copulation. Inedible tokens may be items such as a leaf or twig, a seed tuft, or a silk balloon, which may serve as an indicator of male fitness. More generally, in many species of insects, birds and mammals, males acquire and donate food to females either before, during, or after copulation, termed mate provisioning. The source of the gift may be endogenous (produced by the donor) or exogenous (captured, collected or found by the donor). Exogenous gifts are often food items captured or collected by the donor to feed to the recipient. Endogenous gifts often carry great cost to the donor and usually contain hemolymph or body parts. Endogenous oral gifts are secreted by the donor’s glands (salivary, reproductive, etc.), often carrying nutrients or other substances benefiting the recipient or offspring. In the moth Utetheisa ornatrix, the male feeds the female defensive alkaloids to deter predation on their future eggs and larvae. A gift may be received as an oral gift placed into the recipient's digestive system, a genital gift absorbed through the reproductive tract, of a transdermal gift injected into the body wall of the recipient. In some insects such as katydids and ground wētā, a nutritious genital gift is packaged with the sperm as a spermatophore. In some species, mating can include gifts that benefit the donor but not the recipient. In hermaphroditic land snails, both partners to the courtship produce sperm and eggs, and it is in the interest of each to impregnate the other. Each partner attempts to shoot a mucus-covered love dart into the flesh of the other before attempting to give sperm into the other's ovipore. A dart may cause severe injury, but if it penetrates safely, pheromones in the mucus promote sperm retention in the ovipore, leading to fertilization in the recipient.
Occurrence Nuptial gifts are common in insects and other invertebrates, such as butterflies, fruit flies and katydids. They seem less common in spiders, though the spider species Pisaura mirabilis is known for nuptial gift giving. However, this may reflect experimental bias due to the ease of rearing this species in the laboratory, so more research is required to evaluate the scope of nuptial gifts among arachnids. Courtship feeding is particularly common in bird species.
Role reversal Species in which the male presents the nuptial gift to the female are more common, but the reverse does occur. Female Zeus bugs, Phoreticovelia disparata, present the male with a food item before copulation. The male will then ride in a small depression on the back of the female, as she secretes wax from a gland on the back of her head, which he eats for up to a week. After the sperm is deposited and the male leaves, the female can lay fertile eggs for up to two weeks. Although it is difficult to see any advantages to the female in this scenario, some scientists believe that allowing one male to remain deters other males from violent attempts to copulate with her.
Vertebrates
Great grey shrike
The male great grey shrike, a raptor-like passerine bird, gives prey (rodents, birds, lizards, or large insects) to females immediately before copulation. Shrikes are well known for impaling prey on thorns and sharp sprigs. Great grey shrike females select a mate according to the amount of prey impaled, with larders thus serving as an extended phenotype of the males. A large larder may make a mate more attractive as a regular mate and for occasional copulation with other females.
Invertebrates
Arachnids
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