Sperm storage organs change with female age and mating history in the Golden Silk spider Trichonephila clavipes (Araneae: Araneidae)

• Published in: Journal of zoology (1987) 2024-05, Vol.323 (1), p.19-28
• Main Authors: Land, H., Christenson, T. E., Uhl, G.
• Format: Article
• Language: English
• Subjects: Araneidae; Arthropods; Body organs; Epithelium; Females; Genitalia; histology; Males; mating; Mating behavior; Molting; Moulting; Reproductive behaviour; Sclerotization; Secretion; sexual selection; Silk; Sperm; Sperm competition; sperm priority pattern; sperm storage; Spermatheca; spermathecae; Spermatozoa; Storage organs; Trichonephila clavipes
• ISSN: 0952-8369; 1469-7998
• DOI: 10.1111/jzo.13155

Female sperm storage organs in arthropods are used as taxonomic characters since it is assumed that they do not change after maturation. However, in the Golden Silk spider, Trichonephila clavipes, the shape and sclerotization of the spermathecae change with a mating event. Moreover, mating in T. clavipes consists of several hundred copulations, but the male transfers all sperm during the first insertion of each pedipalp. Given this puzzling mating behaviour, we hypothesize that multiple copulations serve purposes other than sperm transfer and uptake, such as further altering the morphology of the storage site and/or transferring substances other than sperm. We compared virgin female T. clavipes with females after two copulations, one for each spermatheca, and after ad‐libitum mating. Each treatment consisted of two sub‐treatments in which the state of the sperm storage organs was inspected after a short (1–3 days) or a long (11 days) time interval after the female's final moult. The size of the spermathecae increased twofold in all mating treatments compared to virgin females. The thickness of the spermathecal wall increased significantly with time in all treatments similarly. The spermathecal epithelium, which releases secretion into the lumen of the spermathecae, seems most active in virgin females during the time when mating would normally occur and turns less active after mating and with age. The spermathecae contain secretion produced by the female before mating; and after mating, sperm and another secretion transferred by the male. The numerous sperm‐less matings in the ad‐libitum treatment resulted in male secretion in the copulatory ducts of the female genitalia, likely impeding sperm transfer by subsequent males. Out study shows that female genitalia can change considerably after having reached maturity and suggests that sperm‐less matings evolved in the context of sperm competition. Zusammenfassung Arthropoden werden weibliche Samenspeicherorgane als taxonomische Merkmale verwendet, da man davon ausgeht, dass sie sich im Adultstadium nicht verändern. Goldenen Seidenspinne, Trichonephila clavipes, ändern sich jedoch Form und Sklerotisierung der Spermathek durch die Paarung. Außerdem besteht die Paarung bei T. clavipes aus mehreren hundert Kopulationen, aber das Männchen überträgt alle Spermien während der ersten Insertionen der Pedipalpen. Angesichts dieses rätselhaften Paarungsverhaltens stellen wir die Hypothese auf, dass die vielen Kopulationen