Determinants of sperm allocation in males of Allocosa senex (Lycosidae), a species with high reproductive investment

BOLLATTI, FEDRA; OVIEDO DIEGO, MARIELA; AISENBERG, ANITA; PERETTI, ALFREDO V.

Montevideo

Congreso; XXII International Congress of Arachnology; 2023

Allocosa senex males make a high reproductive investment by building burrows to attract sexual partners, copulate inside them, and, after copulation, donate their burrows to females. Females will lay their egg sac here, setting a context of low re-copulation chances with surrounding males. The male investment could result in a trade-off with other determinants of reproductive success, such as ejaculate allocation. We aimed to determine the amount of sperm production and sperm transferred by males, the amount stored by females after copulation, and their relationship to morphological, life history, and behavioral traits during copulation. We performed sexual encounters between virgin pairs (n=20) and recorded their morphological, life history, and behavioral traits. We counted sperm stored in the bulbs and in the spermathecae of the individuals used and added control counts in virgin males. A. senex males showed a low but constant amount of sperm in the bulbs, regardless of their reproductive status. Interestingly, the amount of sperm they transferred was proportionally low, whereas females stored almost all of the transferred sperm. The females' age and body shake number positively affected the amount of sperm remaining in the bulbs (χ2=9.4890; p=0.002, χ2=5.389; p=0.020, respectively), while the age of males affected it negatively (χ2=131.277; p