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Draft:Argiope keyserlingi

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Mating behaviour

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Mate choice

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In Argiope keyserlingi, mate choice dynamics differ between males and females, influenced by factors such as prior mating experiences and food availability. Virgin males tend to prefer virgin females[1], while mated males display no discernible preference[1]. Female aggression towards courting males can vary based on the female's level of food satiation, with better-fed females showing more aggression[1].

Sex pheromones

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Female spiders embed contact pheromones into their web silk[1]. Males detect these pheromones through physical contact with the silk[1] to determine if the female has been mated already[1] and gain other information such as species identity and sexual receptivity[1][2]. A. keyserlingi is also known to use airborne pheromones, possibly to signal the female's location to males[3], but the role of these in male mate choice is not known[1].

Courtship

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Courtship in A. keyserlingi takes place on the female's web and mating takes place on a mating thread[4]. Male courtship behaviours are characterized by a series of vibratory signals from the male, including shudders, abdominal wags, and mating thread dances[5].

Below is a full breakdown of the courtship process leading into copulation:

  1. The male approaches the female by crawling along the frame threads surrounding the web.
  2. Once in the web, the male slowly makes his way to the web hub (the centre of the web), where the female is located.
  3. At the hub, the male ‘tastes’ the female by touching her legs and abdomen with his legs, then passing his legs through his mouth. This may last several minutes to over an hour, occurring in intervals with periods of rest.
  4. The male cuts a small section of the web above the female and constructs a mating thread, possibly reinforcing it with additional lines of silk.
  5. Hanging from the mating thread, the male produces vibrations by plucking and bouncing on the thread.
  6. The female moves onto the mating thread and exposes her genital opening (the epigynum).
  7. The male 'waggles' and begins copulation.

Shudders have been shown to have a strong influence on the female's time to enter a copulatory position[5]. Higher rates of shuddering correspond to greater female reluctance (higher delay)[5], as high shudder rates compromise the duration and quality of the shudder[5]. However, there is evidence that this reduces their risk of post-copulatory cannibalism[5], increasing the male's chance of a second mating attempt.

Females may also display "aggressive pumping" during courtship[5]. Males adjust their courtship behavior based on these signals, with higher rates of female pumping leading to higher delays in the male building the mating thread for copulation[5].

Courtship behaviour is affected by the age of both the male and female[6]. Males display longer shudders when courting older females[6] and older males take longer to approach females and perform more shudders[6].

Sexual cannibalism

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Further information: Sexual cannibalism

Argiope keyserlingi is a sexually cannibalistic species, with females potentially consuming the male after copulation. This results in a phenomenon where males never mate more than twice, with about 50% surviving their first mating, but none surviving a second attempt[1][7]. Research also indicates that each pedipalp cannot be used more than once[7], suggesting males are also physiologically limited to two copulations. Levi suggests that the embolus, found on the pedipalp and involved in sperm transfer[8], may become damaged during copulation, preventing further mating[9].

Cannibalism in A. keyserlingi does not seem to be influenced by the female’s physical condition[10] or serve as a strategy to gain nutrients for egg production.[10][11]. It may function as a form of cryptic female choice[10], allowing females to control sperm transfer and fertilization outcomes. Females can adjust the timing of cannibalism to limit the copulation duration[10] (and therefore amount of sperm transferred), favoring males with a smaller size[10].

Despite no direct link to fecundity, females who consumed the male produce eggs with higher nutrient density[11], however post-copulatory feeding is not what enables this (different nutrient compositions and the male is too small)[11], but the female's somatic reserves[11]. Blamires suggests that protein uptake acts as a trigger to draw out this energy[11].


[1] [10] [5] [7] [11] [2] [12]


Distribution and habitat

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The St Andrew's cross spider can be found mostly in rainforest margins, open forests, and heathlands of eastern Australia.[13] They can also be found in the northern segment of the Northern Territory, in the northern segment of Tasmania, in the western segment of Western Australia, near Tedi River of Papua New Guinea, in the Malakula island of Vanuatu, in all areas of Lord Howe Island.[citation needed] They construct medium-sized webs on low, shrubby vegetation.[13]

Habitat selection

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Individuals tend to prefer closed habitats, with preferences being determined by foilage density, prey abundance, plant height and predator density[12]. They avoid placing their webs within or between trees when there is bird presence[12].

Open habitats tend to only be inhabitated by subadult and adult individuals, with juveniles only being observed in closed habitats.[12].


References

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  1. ^ a b c d e f g h i j Gaskett, A., Herberstein, M., Downes, B., & Elgar, M. (2004). Changes in male mate choice in a sexually cannibalistic orb-web spider (Araneae: Araneidae). Behaviour, 141(10), 1197-1210. https://www.jstor.org/stable/4536195
  2. ^ a b Jason, Q. D., & Mark, A. (2017). Variation in the web-based chemical cues of Argiope keyserlingi. Journal of insect physiology. https://www.sciencedirect.com/science/article/pii/S0022191017300914
  3. ^ Krafft, B. (1982). The significance and complexity of communication in spiders. - In: Spider communication: Mechanisms and ecological significance (P.N. Witt & J.S
  4. ^ https://www.jstor.org/stable/4602073
  5. ^ a b c d e f g h Wignall, A. E., & Herberstein, M. E. (1878). The influence of vibratory courtship on female mating behaviour in orb-web spiders. Argiope keyserlingi. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0053057
  6. ^ a b c https://link.springer.com/article/10.1007/s00114-017-1527-8#Sec5
  7. ^ a b c Herberstein, M. E., Gaskett, A. C., Schneider, J. M., Vella, N. G. F., & Elgar, M. A. (2005). Limits to male copulation frequency: sexual cannibalism and sterility in St Andrew's Cross spiders (Araneae, Araneidae). Ethology, 111(11), 1050-1061. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1439-0310.2005.01114.x
  8. ^ Foellmer, Matthias W. "Broken genitals function as mating plugs and affect sex ratios in the orb-web spider Argiope aurantia." (2008). https://www.researchgate.net/figure/A-Ventral-view-of-male-pedipalps-The-embolus-cap-of-the-male-s-left-palp-right-in_fig1_279901752
  9. ^ Levi, H. W. (1975). Mating behavior and presence of embolus cap in male Araneidae. In Proceedings of the 6th International Arachnological Congress (Vol. 1974, pp. 49-50). Amsterdam.
  10. ^ a b c d e f Elgar, M. A., Schneider, J. M., & Herberstein, M. E. (2000). Female control of paternity in the sexually cannibalistic spider Argiope keyserlingi. Proceedings of the Royal Society of London. Series B: Biological Sciences, 267(1460), 2439-2443. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690835/
  11. ^ a b c d e f Blamires, S. J. (2011). Nutritional implications for sexual cannibalism in a sexually dimorphic orb web spider. Austral Ecology, 36(4), 389-394. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1442-9993.2010.02161.x
  12. ^ a b c d Blamires, S. J., Thompson, M. B., & Hochuli, D. F. (2007). Habitat selection and web plasticity by the orb spider Argiope keyserlingi (Argiopidae): do they compromise foraging success for predator avoidance?. Austral Ecology, 32(5), 551-563. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1442-9993.2007.01727.x
  13. ^ a b Cite error: The named reference :0 was invoked but never defined (see the help page).
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