DOI: 10.5061/dryad.n8pk0p2w5
title: Data from: Juvenile experience with male cues triggers cryptic choice mechanisms in adult female redback spiders

description: Female choice may be linked to population density if expected encounter
 rates with potential mates affects choosiness (energy and risk engaged to
 express mate preferences). Choosiness should covary with male
 availability, which could be assessed using social cues available during
 development. We tested whether exposure of juvenile females to cues of
 male density affected mechanisms of choosiness of adult Latrodectus
 hasselti spiders in two experiments simulating natural contexts. Juvenile
 females were exposed to (1) volatile chemicals from two densities of adult
 males (airborne cues), and (2) tactile, vibrational, and chemical cues
 from adult males or other females (cohabitation cues). As adults, females
 mated readily, regardless of treatment, but there was strong evidence for
 post-copulatory mechanisms of choosiness in females exposed to cues of
 high male availability. These included abbreviated matings (both
 experiments), cannibalism of males before mating was complete
 (cohabitation), and, remarkably, a reduction in the successful placement
 of internal sperm plugs (cohabitation). These shifts decrease the
 likelihood that the first mate would monopolize paternity if the female
 chose to mate again. We conclude that female choosiness may impose strong
 selection on males despite high mating rates, and these effects can hinge
 on cues of male availability detected by juveniles.
description: Data are from two laboratory studies using the outbred offspring
 of field-captured female redback spiders (Latrodectus hasselti). Both
 studies examine how exposure to cues of male density while a juvenile
 affects the behaviour of adult females in terms of mating behaviours
 related to pre- and post-copulatory mechanisms of choosiness.
 <strong>Study 1. Airborne pheromone
 experiment:</strong> This simulates conditions for females maturing
 in the field, which may be exposed to airborne pheromones from nearby
 males and other females. Females in their final two juvenile instars were
 held in a two-by-two design in which they were maintained on a high or low
 nutrient diet and exposed to airborne phermones from a high or low density
 of males (while female density was held constant). Ten family lines were
 used with four females from each family line randomly assigned to one of
 the four treatments. After females became sexually mature, each was paired
 with a single male from a different family line for mating trials, where
 males were size-matched across the 4 treatments to control for
 size-related differences in mating outcomes (see below). 
 <strong>Study 2. Cohabitation
 experiment:</strong> This simulates the naturally-occuring
 encounters between final-instar females and with other spiders that live
 on their webs (juvenile females or adult males). This period of
 'cohabitation' provides females with airborne, vibratory and
 direct contact cues from cohabitants. Females were randomly assigned to
 one of three treatments: a control with no cohabitants, a
 'female' treatment with a juvenile female cohabitant, and a
 'male' treatment with an adult male cohabitant (see paper for
 detailed methods). Females were checked daily for moulting and the total
 duration of the female's final instar was recorded, as well as the
 number of different spiders that had cohabited with the female prior to
 maturity. After females became sexually mature, each was paired with a
 single male from a different family line for mating trials (see below). In
 this experiment, males were not size-matched across treatments, so male
 mass was recorded as a measure of size and used as a covariate in analyses
 of mating outcomes. <strong>Mating
 Trials:</strong> A common procedure was used for mating trials. Each
 female was placed on a frame to build a web. Males were introduced to the
 web and the interactions observed as well as video-recorded. Trials ended
 after 8 hours, when the male was dead, or when 2 hrs had passed following
 a copulation with no additional courtship. Mating outcome and progress
 variables were recorded as the trials proceeded, with some elements
 confirmed after trials by reviewing recordings. After mated females
 produced egg sacs, they were euthanized and their genitalia dissected to
 visualize the presence and location of sperm plugs.
 <strong>Mating variables:</strong> In both
 experiments, we recorded the latency to the first copulation (min) for
 pairs that mated successfully, the number of copulations achieved, and the
 number of successfully placed sperm plugs (in this species, females have 2
 sperm storage organs and a complete mating requires 2 copulations). In the
 cohabitation experiment, we also recorded whether sexual cannibalism
 occurred during trials and if so, whether the male was killed after a
 single copulation.
description: Data are in an excel spreadsheet, one tab per experiment. Missing
 values occur occasionally if observations were missed during mating trials
 and could not be extracted from videos, or if errors were made during the
 dissection of genitalia.