Mating plug

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A mating plug in a female Richardson's ground squirrel (Spermophilus richardsonii) Mating plug.jpg
A mating plug in a female Richardson's ground squirrel (Spermophilus richardsonii)

A mating plug, also known as a copulation plug, sperm plug, vaginal plug, sement or sphragis (Latin, from Greek σφραγίδα 'sfragida' a seal), is gelatinous secretion used in the mating of some species. It is deposited by a male into a female genital tract, such as the vagina, and later hardens into a plug or glues the tract together. [1] While females can expel the plugs afterwards, the male's sperm still gets a time advantage in getting to the egg, which is often the deciding factor in fertilization.

Contents

The mating plug plays an important role in sperm competition and may serve as an alternative and more advantageous strategy to active mate guarding. In some species, such a passive mate-guarding strategy may reduce selection on large male size. [2] Such a strategy may be advantageous because it would allow a male to increase reproductive success by spending more time pursuing new female mates rather than active mate guarding. [2]

Composition

Sphragis on female of Parnassius apollo Parnassius apollo - sphragis 02 (HS).jpg
Sphragis on female of Parnassius apollo

The mating plug of the Bombus terrestris was chemically analyzed and found to consist of palmitic acid, linoleic acid, oleic acid, stearic acid, and cycloprolylproline. [3] It was found that the acids (without cycloprolylproline) were sufficient by themselves to create the plug. Researchers hypothesize that cycloprolylproline reduces female receptivity to further breeding.

Occurrence in nature

Mating plugs are used by many species, including several primates, [4] [2] [5] kangaroos, [6] [7] [8] bees, [9] reptiles, [10] rats, rodents, [11] scorpions, [12] mice, [13] and spiders. [14]

Use of a mating plug as a strategy for reproductive success can also be seen in a few taxa of Lepidoptera and other insects and is often associated with pupal mating. [15] For example, male variable checkerspot butterflies pass a mating plug into the genital opening of females in order to prevent the females from remating and thus protecting their paternity. [16]

The Heliconius charithonia butterfly uses a mating plug in the form of a spermatophore that provides predatory defense chemicals and protein sources for developing eggs. [17] It also acts as an anaphrodisiac that prevents other males from mating with the female. [18] Similarly in Parnassius smintheus butterflies, the male deposits a waxy genital plug on the tip of the female's abdomen to prevent the female from mating again. [19] It contains sperm and important nutrients for the female, [20] and ensures that the male is the only one to fertilize the female’s eggs. [19]

Most species of stingless bees, like Plebeia remota , are only mated once, and thus make use of mating plugs to store all the sperm they collect for future use. [9]

Another species of insect that uses a copulatory plug is Drosophila mettleri , a Sonoran Desert Fly species from the Diptera family. These plugs serve as a means of male-female control during mating interactions. [21]

A peculiar example of mate plugging occurs in Leucauge mariana . Both male and female participation is required to create a mate plug. The male alone cannot create a functional plug. Female participation in creating a mating plugs, and her presumed benefit from them, have led to multiple studies of sexual selection on the sexual behavior of L. mariana. [22]

See also

Related Research Articles

Behavioral ecology Study of the evolutionary basis for animal behavior due to ecological pressures

Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address when studying animal behaviors: What are the proximate causes, ontogeny, survival value, and phylogeny of a behavior?

Sperm competition

Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring. Sperm competition is an evolutionary pressure on males, and has led to the development of adaptations to increase males' chance of reproductive success. Sperm competition results in a sexual conflict of interest between males and females. Males have evolved several defensive tactics including: mate-guarding, mating plugs, and releasing toxic seminal substances to reduce female re-mating tendencies to cope with sperm competition. Offensive tactics of sperm competition involve direct interference by one male on the reproductive success of another male, for instance by physically removing another male's sperm prior to mating with a female. For an example, see Gryllus bimaculatus.

Spermatophore Packet containing sperm in invertebrate reproduction

A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores may additionally contain nourishment for the female, in which case it is called a nuptial gift, as in the instance of bush crickets. In the case of the toxic moth Utetheisa ornatrix, the spermatophore includes sperm, nutrients, and pyrrolizidine alkaloids which prevent predation because it is poisonous to most organisms. However, in some species such as the Edith's checkerspot butterfly, the "gift" provides little nutrient value. The weight of the spermatophore transferred at mating has little effect on female reproductive output.

Animal sexual behaviour Sexual behavior of non-human animals

Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity. Other sexual behaviour may be reproductively motivated or non-reproductively motivated.

<i>Heliconius charithonia</i> Species of butterfly

Heliconius charithonia, the zebra longwing or zebra heliconian, is a species of butterfly belonging to the subfamily Heliconiinae of the family Nymphalidae. It was first described by Carl Linnaeus in his 1767 12th edition of Systema Naturae. The boldly striped black and white wing pattern is aposematic, warning off predators.

Sexual conflict Term in evolutionary biology

Sexual conflict or sexual antagonism occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly over the mode and frequency of mating, potentially leading to an evolutionary arms race between males and females. In one example, males may benefit from multiple matings, while multiple matings may harm or endanger females, due to the anatomical differences of that species.

Sexual cannibalism

Sexual cannibalism is when an animal cannibalizes its mate prior to, or after copulation. It is a trait observed in many arachnid orders and several insect orders. Several hypotheses to explain this seemingly paradoxical behavior have been proposed. The adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis are among the proposed hypotheses to explain how sexual cannibalism evolved. This behavior is believed to have evolved as a manifestation of sexual conflict, occurring when the reproductive interests of males and females differ. In many species that exhibit sexual cannibalism, the female consumes the male upon detection. Females of cannibalistic species are generally hostile and unwilling to mate; thus many males of these species have developed adaptive behaviors to counteract female aggression.

Traumatic insemination Mating practice in invertebrates

Traumatic insemination, also known as hypodermic insemination, is the mating practice in some species of invertebrates in which the male pierces the female's abdomen with his aedeagus and injects his sperm through the wound into her abdominal cavity (hemocoel). The sperm diffuse through the female's hemolymph, reaching the ovaries and resulting in fertilization.

Ediths checkerspot Species of butterfly

Edith's checkerspot is a species of butterfly in the family Nymphalidae. It is a resident species of western North America and among the subspecies, entomologists have long been intrigued by their many phenotypic variations in coloration, wing length, and overall body size. Most populations are monophagous and rely on plants including Plantago erecta and Orthocarpus densiflorus as its host species in developing from eggs through to larvae, pupae, and mature butterflies. Males exhibit polygyny whereas females rarely mate more than once. Males devote most of their attention to mate acquisition, and such mate locating strategies such as hilltopping behavior has developed. Climate change and habitat destruction has impacted certain subspecies. Two subspecies in particular, Euphydryas editha quino and Euphydryas editha bayensis, are currently under protection via the Endangered Species Act.

Reproductive system of gastropods

The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals. Their reproductive strategies also vary greatly, see Mating of gastropods.

An intromittent organ is a general term for an external organ of a male organism that is specialized to deliver sperm during copulation. Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species fertilize their eggs externally, although there are exceptions. For many species in the animal kingdom, the male intromittent organ is a hallmark characteristic of internal fertilization.

<i>Parnassius smintheus</i> Species of butterfly

Parnassius smintheus, the Rocky Mountain parnassian or Rocky Mountain apollo, is a high-altitude butterfly found in the Rocky Mountains throughout the United States and Canada. It is a member of the snow Apollo genus (Parnassius) of the swallowtail family (Papilionidae). The butterfly ranges in color from white to pale yellow-brown, with red and black markings that indicate to predators it is unpalatable.

Sexual antagonistic co-evolution is the relationship between males and females where sexual morphology changes over time to counteract the opposite's sex traits to achieve the maximum reproductive success. This has been compared to an arms race between sexes. In many cases, male mating behavior is detrimental to the female's fitness. For example, when insects reproduce by means of traumatic insemination, it is very disadvantageous to the female's health. During mating, males will try to inseminate as many females as possible, however, the more times a female's abdomen is punctured, the less likely she is to survive. Females that possess traits to avoid multiple matings will be more likely to survive, resulting in a change in morphology. In males, genitalia is relatively simple and more likely to vary among generations compared to female genitalia. This results in a new trait that females have to avoid in order to survive.

Lepidoptera genitalia

The study of the genitalia of Lepidoptera is important for Lepidoptera taxonomy in addition to development, anatomy and natural history. The genitalia are complex and provide the basis for species discrimination in most families and also in family identification. The genitalia are attached onto the tenth or most distal segment of the abdomen. Lepidoptera have some of the most complex genital structures in the insect groups with a wide variety of complex spines, setae, scales and tufts in males, claspers of different shapes and different modifications of the ductus bursae in females.

Female copulatory vocalizations, also called female copulation calls or coital vocalizations, are produced by female primates, including human females, and female non-primates. Copulatory vocalizations usually occur during copulation and are hence related to sexual activity. Vocalizations that occur before intercourse, for the purpose of attracting mates, are known as mating calls.

A nuptial gift is a nutritional gift given by one partner in some animals' sexual reproduction practices.

Sexual selection in mammals

Sexual selection in mammals started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, consisting of male-male competition and mate choice that mold the development of future phenotypes in a population for a given species.

Zorotypus impolitus is a species of insect in the order Zoraptera.

Cryptic female choice is a form of mate choice which occurs both in pre and post copulatory circumstances when females in certain species use physical or chemical mechanisms to control a male's success of fertilizing their ova or ovum; i.e. by selecting whether sperm are successful in fertilizing their eggs or not. It occurs in internally-fertilizing species and involves differential use of sperm by females when sperm are available in the reproductive tract.

<i>Leucauge mariana</i> Species of spider

Leucauge mariana is a long-jawed orb weaver spider, native to Central America and South America. Its web building and sexual behavior have been studied extensively. Males perform several kinds courtship behavior to induce females to copulate and to use their sperm.

References

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