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Cryptic Female Choice
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. The present understanding of cryptic female choice is largely thanks to the extensive research and analysis done by William G. Eberhard. The term ‘cryptic’ according to Eberhard is meant to describe an internal and thereby hidden choice some female organisms are able to make following insemination with regards to sperm selection. In male species with intromittent organs, during copulation, a male inserts his reproductive organ into that of a female's so as to inseminate her with his genetic material. Through the developmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mate Choice
Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior.Bateson, Paul Patrick Gordon. "Mate Choice." Mate Choice, Cambridge University Press, 1985 In other words, before an animal engages with a potential mate, they first evaluate various aspects of that mate which are indicative of quality—such as the resources or phenotypes they have—and evaluate whether or not those particular trait(s) are somehow beneficial to them. The evaluation will then incur a response of some sort. These mechanisms are a part of evolutionary change because they operate in a way that causes the qualities that are desired in a mate to be more frequently passed on to each generation over time. For example, if female peacocks desire mates who have a colourful plumage, then this trait will increase in frequency over time as male peacocks with a colourful plumage will hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Female Sperm Storage
Female sperm storage is a biological process and often a type of sexual selection in which sperm cells transferred to a female during mating are temporarily retained within a specific part of the reproductive tract before the oocyte, or egg, is fertilized. The site of storage is variable among different animal taxa and ranges from structures that appear to function solely for sperm retention, such as insect spermatheca and bird sperm storage tubules (bird anatomy), to more general regions of the reproductive tract enriched with receptors to which sperm associate before fertilization, such as the caudal portion of the cow oviduct containing sperm-associating annexins. Female sperm storage is an integral stage in the reproductive process for many animals with internal fertilization. It has several documented biological functions including: * Supporting the sperm by: a.) enabling sperm to undergo biochemical transitions, called capacitation and motility hyperactivation, in which they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theropithecus Gelada
The gelada (''Theropithecus gelada'', am, ጭላዳ, translit=č̣əlada), sometimes called the bleeding-heart monkey or the gelada baboon, is a species of Old World monkey found only in the Ethiopian Highlands, living at elevations of above sea level. It is the only living member of the genus '' Theropithecus'', a name derived from the Greek root words for "beast-ape". Like its close relatives in genus ''Papio'', the baboons, it is largely terrestrial, spending much of its time foraging in grasslands, with grasses comprising up to 90% of its diet. It has buff to dark brown hair with a dark face and pale eyelids. Adult males have longer hair on their backs and a conspicuous bright red patch of skin shaped like an hourglass on their chests. Females also have a bare patch of skin but it is less pronounced, except during estrus, when it brightens and exhibits a "necklace" of fluid-filled blisters. Males average and females average in weight. The head-body length is with a tail o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pisaura Mirabilis
The nursery web spider ''Pisaura mirabilis'' is a spider species of the family Pisauridae. Description Striking characteristics of ''Pisaura mirabilis'' are its long legs (the fourth one being the longest) and its slender abdomen ( opisthosoma). The male is between 10 and 13 mm, while the female is 12 to 15 mm. After final ecdysis, the male spiders weigh on average 54 mg and females 68 mg. The prosoma ( cephalothorax) is variable in color, ranging from light to reddish brown and from gray to black. A lighter stripe is visible down the middle of the prosoma. The opisthosoma (abdomen) is long and narrow and tapered towards the rear end. The female spiders has a dark patch ( epigyne) on the underside of her abdomen that includes the copulatory organs. Male genital openings can be found at the same location, but remain inconspicuous. Patterning and coloration varies due to polymorphism. These patterns, which can be caused by hair and pigments, change with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatophore
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. Arthropods Spermatophores are the norm in arachnids and several soil arthropods. In various insects, such as bush crickets, the spermatophore is often surrounded by a proteinaceous spermatophyla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Lizard
The sand lizard (''Lacerta agilis'') is a lacertid lizard distributed across most of Europe from France and across the continent to Lake Baikal in Russia. It does not occur in European Turkey. Its distribution is often patchy. In the sand lizard's northern populations, such as in Great Britain, it is only able to survive along coastal heathlands where the sand is hot enough to incubate their eggs. Males are known for their bright colorations and aggressive behaviors when competing for females. Their mating process is unique because of its relatively short time period and because males are generally more selective with who they mate with than females. Females typically only lay a single clutch in a year. Sand lizards spend most of their time basking, foraging, or under vegetation and prefer to live in diverse habitats. Males have their own home territories that are very wide and often overlap with other males. These males compete with each other while females have smaller home ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cassidinae
The Cassidinae (tortoise and leaf-mining beetles) are a subfamily of the leaf beetles, or Chrysomelidae. The antennae arise close to each other and some members have the pronotal and elytral edges extended to the side and covering the legs so as to give them the common name of tortoise beetles. Some members, such as in the tribe Hispini, are notable for the spiny outgrowths to the pronotum and elytra. Description The "cassidoids" have a rounded outline with the edges of the pronotum and elytra expanded, spreading out to cover the legs and head. They are often colourful and metallic, with ornate sculpturing; a few species have the ability to change the colour due to water movements within the translucent cuticle. All members of the subfamily have the mouthparts reduced into a cavity in the head capsule, the legs have four segmented tarsi. The hispoids have larvae that are leaf miners, while the cassidoids feed on the plant surfaces, sometimes covering their bodies with faecal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Flour Beetle
The red flour beetle (''Tribolium castaneum'') is a species of beetle in the family Tenebrionidae, the darkling beetles. It is a worldwide pest of stored products, particularly food grains, and a model organism for ethological and food safety research. Description Adult beetles are small, around 3-4mm long (1/8 inches), of a uniform rust, brown or black color. Head and pronotum are sometimes darker than rest of body. Ecology The red flour beetle attacks stored grain and other food products including flour, cereals, pasta, biscuits, beans, and nuts, causing loss and damage. The United Nations, in a recent post-harvest compendium, estimated that ''Tribolium castaneum'' and ''Tribolium confusum'', the confused flour beetle, are "the two most common secondary pests of all plant commodities in store throughout the world." Distribution and habitat The red flour beetle is of Indo-Australian origin and less able to survive outdoors than the closely related species ''Tribolium confu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copulatory Plug
A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς ''sphragis'', "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. 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. 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. 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. Composition The mating plug of the ''Bombus terrestris'' was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intromittent Organ
An intromittent organ is any 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. Species with intromittent organs Invertebrates Molluscs Male cephalopods have a specialized arm, the hectocotylus, which is inserted into the female's mantle cavity to deliver a spermatophore during copulation. In some species, the hectocotylus breaks off inside the female's mantle cavity; in others, it can be used repeatedly to copulate with different females. Arachnids In spiders the intromittent organs are the male pedipalps, even though these are not primarily sexual organs, but serve as indirect mating organs; in the male the pedipalps have hollow, clubbed tips, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mating Plug
A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς ''sphragis'', "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. 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. 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. 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. Composition The mating plug of the '' Bombus terrestris'' was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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