Worthless and Nutritive Nuptial Gifts: Mating Duration, Sperm Stored and Potential Female Decisions in Spiders

Abstract

In nuptial gift-giving species females sometimes select their potential mates based on the presence and size of the gift. But in some species, such as the Neotropical polyandrous spider Paratrechalea ornate male gifts vary in quality, from nutritive to worthless, and this male strategy can be in conflict with female nutritional benefits. In this species, males without gifts experience a reduction in mating success and duration, while males that offer worthless or genuine nutritive gifts mate with similar frequencies and durations. The female apparently controls the duration of copulation. Thus, there is scope for females to favour males offering gifts and further if these are nutritious, via post-copulatory processes. We first tested whether females differentially store sperm from males that offer the highest nutritional benefits by experimentally presenting females with males that offer either nutritive or worthless gifts (uninterrupted matings). Second, we carried out another set of experiments to examine whether females can select sperm based only on gift presence. This time we interrupted matings after the first pedipalp insertion, thus matching number of insertions and mating duration for males that: offered and did not offer gift. Our results showed that the amount of sperm stored is positive related to mating duration in all groups, except in matings with worthless gifts. Gift presence itself did not affect the sperm stored by females, while they store similar number of sperm in matings with males offering either nutritive or worthless gifts. We discuss whether females prefer males with gifts regardless, if content, because it represents an attractive and/or reliable signal. Or alternatively, they prefer nutritive nuptial gifts, as they are an important source of food supply and/or signal of male donor ability.

Females of a gift-giving spider do not trade sex for food gifts: a consequence of male deception?

“…With this procedure, we allowed females to encounter numerous males carrying silk wrapped gifts throughout the reproductive period, and thus they had many mating opportunities before constructing the first eggsac. Following a previous protocol [ 26 , 28 ], one experimental group was the Well fed-Nutritive gift group ( N = 21), where well-fed females were exposed to males offering nutritive gifts, which consisted of a recently captured housefly ( Musca domestica ). A second group was the Well fed-Worthless gift group ( N = 22), where well-fed females were exposed to males offering worthless gifts consisting of the exuviae of a mealworm ( Tenebrio molitor larva).…”

“…This is because field data sampled along the reproductive season from three different populations in Uruguay indicate that 70% of nuptial gifts are worthless [ 26 ]. Although males can court without a gift, they experience a reduced female acceptance rate, shorter mating duration as well as lower sperm storage in the female spermathecae [ 26 – 28 ]. This creates selective pressure on the males to offer nuptial gifts.…”

Males of a Neotropical spider adjust prey‐gift construction but not mate search in response to sperm competition

“…Third, given the higher investment towards higher quality females and the possibility that well‐wrapped gifts extend copulation duration, long‐lasting copulation with an unmated female can improve males’ fertilization success, even if the female later accepts other males. This may happen because males with high‐quality gifts have more time to court the partner and their sperm can be favoured by cryptic female choice (Albo & Peretti, 2015).…”

Female wolf spiders exert cryptic control drastically reducing ejaculate size

“…Second, they receive immobile and encapsulated sperm that is stored in their spermathecae, and fertilisation can occur several months after mating, when females activate the sperm and oviposit (Foelix, 2011;Useta, Huber, & Costa, 2007;Vöcking, Uhl, & Michalik, 2013) but see (Eberhard & Huber, 1998). Such scenario generates favourable conditions for strong female control on male gametes (Albo & Peretti, 2015;Albo, Toft, & Bilde, 2014;Bukowski & Christenson, 1997;Peretti & Eberhard, 2010;Schneider & Lesmono, 2009;Watson, 1991), even to the point of expelling all sperm from a previous male (Burger, 2007). On the other hand, it is known that to increase fertilisation success male spiders can invest in the amount of sperm transferred, and it is usually assumed that sperm number correlates positively with mating duration and number of pedipalp insertions (Elgar, 1995;Schneider & Andrade, 2011).…”