Nuptial gift
[1] Nuptial gifting is at the intersection of sexual selection, nutritional ecology, and life history theory, creating a link between the three.
In many species of animals, including birds, insects, and spiders, this takes the form of a food item that is transferred from a male to a female just prior to copulation.
[1] They often carry nutrients that are severely lacking in the body of the recipient, these include types of macronutrients, micronutrients, water and defensive chemicals.
If shot in the incorrect place, the dart could puncture vital organs of the receiver resulting in permanent reproductive ability damage or death.
These extra nutrients in the sperm are assimilated by the female and are thought to enhance the fitness of the offspring produced, thus increasing the probability that a male passes on its genes.
In many species of insects, birds and mammals, males acquire and donate food to females either before, during, or after copulation (termed mate provisioning, courtship feeding, nuptial gift giving, or meat-for-sex).
Males may relinquish body parts, produce glandular secretions, or share prey or other food to gain fitness benefits via natural and sexual selection.
Great grey shrike females select a mate according to the size of prey impaled, with larders thus serving as an extended phenotype of a male.
[20] In spiders, nuptial gifts in the form of prey are restricted to a few species from two families belonging to the superfamily Lycosoidea: Pisauridae and Trechaleidae.
In Paratrechalea ornata, males were observed wrapping prey carrion and occasionally inedible items such as plant seeds.
[9] In decorated crickets, Gryllodes sigillatus (Orthoptera: Gryllidae), the nuptial food gift is a spermatophylax (a large, gelatinous, sperm-free mass) that surrounds a smaller, sperm-containing ampulla.
Together, the spermatophylax and the ampulla constitute the male's spermatophore, which is transferred to the female during copulation and remains attached outside her body at the base of her ovipositor.
[27] It may be possible the females are using age and gift quality as a proxy for mates with good genes as their offspring are likely to have high relative fitness.
[28] During mating in the ornate moth (Utetheisa ornatrix), males provide the female with a spermatophore containing nutrients, sperm and alkaloids that serve as chemical defense from predators.
[29] Females receive spermatophores from several males and direct a postcopulatory selection process in which they decide what sperm will fertilize their eggs.
Older males thus tend to produce larger spermatophores with more nuptial gift content since there are less future reproductive episodes possible for them.
Females are able to recognize and preferentially mate with males reared on higher-quality host plants as larvae, because they are able to provide superior nuptial gifts with higher protein and spermatophore content.
[33] Nuptial gifts are widespread in insects such as the six-spot burnet (Zygaena filipendulae), and comprise food items or glandular products offered as paternal investment in offspring and/or to promote mating.
Males in poor condition with a limited supply of saliva may deliberately delay initiating copulations to decrease the probability that their costly gift is rejected and, thus, wasted.
[36] Individuals of both sexes of the Sonoran Desert fly, Drosophila mettleri, exchange a mixture of yeast and bacteria that is placed on the nesting site and used as a means of exposing larvae to natural florae needed for greater lifetime fitness and for nutrition.
[37] The prevention of nutritional gift production and exchange has been shown to decrease both male mating success and female egg count.
[10] In fruit flies, katydids, and scorpionflies, nuptial gifts contain substances that reduce a female's receptivity to additional matings.
While nuptial gifts also may boost female fecundity, from a male's perspective, such investment will only be beneficial if it increases the number of his own offspring.
Research has suggested that the gifts presented by males temporarily obstruct the female's capacity to manage the copulation event.
Albo and Costa conducted an experiment with Paratrechala ornata spiders to determine the function of the nuptial gift.
Nuptial gifts would allow males to control copulation duration and to accelerate female oviposition, improving sperm supply and paternity, and minimizing possible costs of remating with polyandrous individuals.
[44] This effect demonstrates sexual selection's ability to make one sex more discriminatory than the other, since females may negatively impact their output of offspring by refusing mating events with males that do not offer gifts.
It has been shown that female fireflies will route spermatophore (contain sperm and are produced by the accessory gland) nutrients throughout their body from a few hours up to a few days.
[47] This allows the “cheating” organism to have a chance at copulating without incurring the costs associated with creating a real nuptial gift for their mate.
[48] Female Pisaura mirabilis spiders have been shown to pick up nuptial gifts more quickly if they more closely resembled their egg sac.
