Maratus volans

Maratus volans
Maratus volans
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Courtship rituals in M. volans.
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Order:	Araneae
Suborder:	Araneomorphae
Family:	Salticidae
Subfamily:	Euophryinae
Genus:	Maratus
Species:	M. volans
Binomial name
Maratus volans (O. P-Cambridge, 1874)
Synonyms
Saitis volans Maratus amoenus

Maratus volans is a species in the jumping spider family, belonging to the peacock spider genus.

Description

Octavius Pickard-Cambridge, who is credited with the first formal biological description and hence is noted as the person assigning it its binomial name (he originally named it Salticus volans; its name was changed to Maratus volans by Marek Zabka in 1991), wrote in his first description of it that "it is difficult to describe adequately the great beauty of the colouring of this spider".

The red, blue and black colored males have flap-like extensions of the abdomen with white hairs that can be folded down. They are used for display during mating: the male raises his abdomen, then expands and raises the flaps so that the abdomen forms a white-fringed, circular field of color. The species, and indeed the whole genus Maratus have been compared to peacocks in this respect. The third pair of legs is also raised for display, showing a brush of black hairs and white tips. These legs are also used in a clapping motion to further attract a female's attention. While approaching the female, the male will vibrate his abdomen while waving raised legs and tail, and dance from side to side.

Both sexes reach about 5 mm in body length. Females and immatures of both sexes are brown but have colour patterns by which they can be distinguished from related species.

Though a female may witness a male's dance, she could already be carrying eggs or simply not be impressed. If the male continues his dance when the female is not interested, she will attempt to attack, kill, and feed on him (Evans, 1990). If the male is quick enough he uses his ability to jump long distances to escape her, if he is not quick enough he is eaten by the perturbed female. This may also happen even if the female is interested and allows the male to mate with her. The behavior of the female M. volans suggests why the males have developed unique sexual dimorphic features and courtship behavior (Thornhill, 1984). It is important to note that M. volans not only use their inherited colorful opisthosomal flaps to lure the attention of the female but much of the mating ritual consist of waving and vibrating the third legs. This calls to question, why peacock spiders do not stick with just one signal in order to lure a female? The M. volans mating ritual can last anywhere between four and fifty-minutes (Girard, 2011). That is a lot of time and energy invested into a female that may not even mate with that particular male. This multi-modal approach to mating has been studied by Jakob Bro-Jergensen. In his published work, he states "When both sexes are allowed to respond optimally by introducing adaptive dynamics to a standard runaway model of condition dependent signaling, multiple signals can coexist even if the signal preferences entail significant costs"(Bro-Jorgensen, 2009). He goes on to explain that the potential sexual success outweighs the relatively low costs of the mating ritual. The mating rituals of M. volans is one example of intersexual selection. Intersexual selection is characterized by the competition of a male species with its female species, in which the female will decide which male she will mate with depending on certain phenotypic traits and relative fitness. It has been stated that M. volans males may have evolved to have such unique traits because of this sexual selection (Prum, 2010). The female spiders have been selecting for the most unique and elaborate dances, therefore, the female is selecting for good genes. If the female decides to mate with a male that has the brightest colors and unique dancing patterns, it is likely that her offspring will have similarly unique courting advantages and succeed sexually as well (Thornhill, 1984). In contrast, if a female were to mate with a male that has a dull color pattern and does not dance appropriately, her offspring will likely have the same coloring pattern and may not succeed sexually, ultimately putting the species existence in danger. What was just described is an example of runaway sexual selection model. In the runaway sexual selection model, it is to be assumed that "If the genetic correlation between trait and preference is extremely high, this system can "run away" in a positive feedback loop, like a snowball rolling down a snowy mountain and accelerating as it becomes larger and larger."(Bergstrom, 2012) An effect of this would be that across many generations, male coloration would become more and more elaborate because the male gene for color and the female gene for preference are linked. It should be noted that the runaway sexual selection model and good genes model of intersexual selection are difficult to distinguish from one another. One distinguishing characteristic of the runaway sexual selection model is that the evolution of the selected gene can be detrimental to either the male or female. Because the male risks death in attempting to mate, the runaway sexual selection model is used to describe M. volans.

This species of spider poses no threat to humans.

Distribution

M. volans is confined to specific parts of Australia (Queensland, New South Wales, Australian Capital Territory, Western Australia and Tasmania).

Name

The species name—volans—means "flying" in Latin, because in his description of them O.P-Cambridge indicated that the person who sent him the specimens from New South Wales had told him that he had seen the spiders "actually using [the flaps] as wings or supporters to sustain the length of their leaps." This belief has been debunked by the Australasian Arachnological Society. Nevertheless, the designation "volans" remains.

References

• Ed Nieuwenhuys: Peacock spider
• Platnick, Norman I. (2009): The world spider catalog, version 9.5. American Museum of Natural History.
• David Edwin Hill 2009: "Euophryine jumping spiders that extend their third legs during courtship (Araneaee: Salticidia: Euophryinae: Maratus, Saitis)". Peckhamia 74(1): 1-27.
• Jurgen C Otto and David E Hill 2011: "An illustrated review of the known peacock spiders of the genus Maratus from Australia, with description of a new species (Araneae: Salticidae: Euophryinae)." Peckhamia 96.1: 1-27.
• Thornhill, R., Alcock, J., (1984).The Evolution of Insect Mating Systems, Science Ne Series, 223(4638), 808-809

External links

• Images of M. volans, including courtship dance
• Diagnostic drawings of M. volans
• YouTube: Footage of M. volans mating dance
• Info on different species of peacock spider, including M. volans