Nuptial Gifts Flashcards
What are nuptial gifts?
Common in human courtship
Natural gifts seem to come and less interesting ornamentation or weaponry
However, it played an important role in the mating system
What non-gametic materials are typically transferred from males to females during courtship?
Lipids carbohydrates, proteins, peptides, amino acids, uric acid, minerals, water, antipredator defence compounds and a chemical that induce a physiological response
Sperm competition
Thought to be the primary reason while males of a natural gifts to females and allow females to cannibalism
Nuptial gifts as mating effort
The males paternity and the number of sperm he transfers often correlates with the size of the gift
Forms of animal nuptial gifts
Food offerings, various male body parts (all the whole male), hemolymph, salivary gland secretions, seminal fluid, spermatophores and ’love darts’
Net fitness benefit on males
The collection and manufacture of nuptial gifts is costly for males
The gift given males must able to sire a more offspring than other males in the same population
Seven episodes of selection for male gifts.
- Mate attraction
- Copulation
- Insemination
- Sperm transferred
- Sperm storage
- Paternity share
- Female fecundity
- Egg and offspring survival
Exogenous oral gifts
This consists of food items that males capture all collected, so generally contain nutritive material- these gifts are protected to deliver net fitness to benefit the females
Three ways these gifts are generally predicted to increase male fitness
- They can be assessed visually prior to meeting, exogenous oral gifts should affect a mates ability to attract females
- Females remain stationary while feeding, food gives make it easier for males to initiate population
- Females feed on these gifts while copulating, these gifts are expected to increase both copulation duration and quality of sperm transferred
Endogenous oral gifts
These are secretions made by the males salivary, reproductive and other glands, as well as other parts of the male body
How do these gifts help males increase fitness?
They can be inspected by the females, they could resemble exogenous gifts
Males may be selected to incorporate phagostimulants the increase the gifts gustatory appeal and also to alter gift composition to slow female consumption rates
Cricket example
In some ground crickets, females imbibe hemolymph from a specialised spur located on the mates hindlegs
Cockroaches example
In cockroaches, males augment their spermatophores to be important nitrogen source for females and their eggs
Mantids and orb-weaving spiders example
These engage in sexual cannibalism were females kill and consume males either before or after insemination
Endogenous genital gifts
These are materials that are produced by the secretory tissue in the male reproductive tract, transferred in seminal fluid, or spermatophores and absorbed through the female genital tract
Like orally-ingested glandular gifts, these products of male reproductive glands can also supply nutrients that absenct or limited within females diets
Endogenous genital gifts and defensive compounds
These can contain defensive compounds that protects the female or her eggs against predators or microbial attack
Endogenous genital gifts and female fitness
These may reduce female fitness
In some species, male gifts contain anti-aphrodisiacs into reduce a females likelihood of remating
Selection on males to reduce sperm competition risk favour inclusion of such substances, butanti-aphrodisiacs can lower female net fitness it they overly depress remating rates
What are endogenous transdermal gifts?
Male seminal and glandular products that are transferred and absorbed outside the females digestive or reproductive systems
This happens during extragenital insemination in bedbugs
Selection on transdermal gifts may favour the inclusion of compounds that benefit males but may be detrimental to female fitness
What is a love dart?
A sharp, calcareous or chitinous dart that some hermaphroditic land snails and slugs create
The love dart is not a penial stylet- the exchange of sperm between the snails is a completely separate part of the mating progression
The dart can strongly favour the reproductive outcome for the snail that is able to lodge a dart in its partners - the mucus on the dart introduces a hormone-like substance that allowsfar more of its sperm to survive
Gift giving- heteropteran Zeus bugs
Males feed upon glandular secretions provided by the female
A male Zeus bug clings to the back of a female. The nuptial gift to him is a place to stay while they mate, complete with snacks
Evolution of worthless gifts
The evolution of worthless gift-giving is potentially favoured when the male may reduce the cost of gift production by eating the prey before offering it to females or by offering inedible items
Males seem to hold the upper hand in this co-evolutionary cycle, unless females counteract the deception via some postcopulatory process
