DOI: 10.5061/dryad.rv15dv4gf
title: The effects of food availability on reproductive success in a false widow spider

description: All animals require food to survive, grow, reproduce, and thus optimize
 fitness in nature. Food availability can profoundly affect demographic
 parameters such as longevity and fecundity. Here, we compared reproductive
 parameters in the false widow spider, Steatoda grossa (Araneae,
 Theridiidae), when the availability and size of prey (the house cricket,
 Acheta domesticus) were manipulated. Adult mated female spiders that were
 fed weekly (constant prey treatment) produced more progeny during their
 lifetime than females fed every 3 weeks (intermittent prey
 treatment). Furthermore, the monitoring of fecundity schedules showed that
 over the first 10 egg sacs, the mean number of neonate spiderlings per egg
 sac was around 40% higher in constantly fed than intermittently fed
 spiders. Time intervals between egg sac productions were generally higher
 when prey availability was lower. Some females lost more than 50% of their
 body mass after the production of the first egg sac, although reproductive
 investment tended to decrease thereafter. The amount of prey offered to
 females significantly affected mass gain between reproductive events, but
 fewer progeny were produced by females per egg sac, as well as
 cumulatively over the first three egg sacs, when they were only fed small
 prey. Starved females that had not produced egg sacs in several months
 exhibited total reproductive recovery when fed. Our results demonstrate
 the importance of prey attributes on S. grossa reproduction. Furthermore,
 females invest remarkably large amounts of resources during each
 reproductive cycle and over the course of a lifetime.
description: This study aims to investigate the effects of food availability
 on reproductive success. The experiment was divided into two parts: a
 lifetime experiment, which investigates a long-term effect on the quantity
 of viable offspring, reproductive intervals, and female body mass changes,
 and a three-month experiment with more divided treatments, which explains
 the details of the reproductive performance from the first 3 egg sacs. We
 titled these two experiments “long-term experiment” and “short-term
 experiment” respectively. In the long-term experiment,
 adult females were fed one cricket per week before they were mated
 according to the protocol described in the <em>Animal collection and
 rearing</em> section. Following mating, they were divided into two
 feeding groups: 1) Intermitted feeding (n = 36), where spiders received
 one cricket every 3 weeks, and 2) Constant feeding (n = 57), where spiders
 received one cricket every 2-3 days. Crickets for feeding weighed between
 150 and 200 mg. We recorded the number of spiderlings hatched from each
 egg sac and the duration of intervals between egg sac production until the
 females died. For females’ body mass monitoring, we randomly selected 10
 virgin females from the rearing and mated them. Crickets (weighing between
 150mg to 200mg) were offered once a week regularly, and one extra cricket
 after producing an egg sac. The body mass changes one day before and after
 producing egg sacs were recorded for the first five egg sacs.
 In the short-term experiment, in which we varied the amount of
 food that the females were provided with before and after mating, adult
 females were divided into five groups (with 8 to 11 individuals per
 group), each receiving varying quantities and frequencies of crickets. The
 food treatments are as follows:  two large crickets per
 week (~240mg per week);  one large cricket per week
 (~120mg per week);  one medium cricket per week (~60mg
 per week);  one medium cricket every 2 weeks (~30mg per
 week);  one small cricket every 2 weeks (~5mg per
 week). We used the approximate food mass provided to
 spiders as treatment names. Female spiders were exposed to these feeding
 regimes 2 months before mating and following matings until the females had
 produced 3 egg sacs or after 2 months if no egg sacs were produced. Body
 mass of the females was measured at the beginning of the experiment, 50
 days after initiation of the feeding regime, and 7 days after mating.
 Cannibalism behavior was checked within 48 hours after mating. When an egg
 sac was produced, the date and its mass were recorded. The number of
 spiderlings hatching, the number of eggs that did not develop into
 spiderlings, and the mean weight of spiderlings per egg sac were recorded.
 If females did not produce egg sacs after 2 months (treatment 5mg), they
 were offered crickets weekly and monitored for 1 month or until their time
 of reproduction. Females that died during experimental months were
 excluded from the experiment, and data from these females were
 removed.
description: # The effects of food availability on reproductive success in a false
 widow spider
 [https://doi.org/10.5061/dryad.rv15dv4gf](https://doi.org/10.5061/dryad.rv15dv4gf) ## Description of the data and file structure #### Column Heading Discriptors for **final_dataset_s**heet 1 (short term):          fe         # unique identifier of the females treatment         # food treatments, these values refer to the approximate body mass of crickets we provided per week, 5mg, 30mg, 60mg, 120mg, and 240mg weight on 25/4            #  female body mass on the day we started different food treatments, unit = mg weight on 15/6            #  female body mass after 51 days, unit = mg weight on 20/7            #  female body mass around a week after mating, unit = mg mate_day        #  the day for mating courtship_duration      #  the duration for the male to perform courtship behavior, unit = mins cannibal           #  if females did cannibalise the male within 24 hours after mating, 1 refers to yes, 0 refers to no eggX   #  the day for X egg sac appearing, e.g., 1st_egg means the date for the first egg sac production weightX          #  the weight of X egg sac, e.g., 1st_weight means the weight of the first egg sac from this female, unit = mg numberX         #  the number of spiderlings hatched from X egg sac, e.g., 1st_number means the number of spiderlings in the first egg sac from this female meanweightX  #  the mean weight of spiderlings from X egg sac, e.g., 1st_meanweight means the mean weight of spiderlings from the first egg sac, unit = mg deadeggsX      #  the egg numbers that failed to hatch, e.g., 1st_deadeggs means the number of eggs that failed to hatch from the first egg sac #### Column Heading Discriptors for **final_dataset_s**heet 2 (lifetime reproduction):     treatment         # food treatments, constant and intermittent. When it is constant, it means we offer 1 cricket every 2-3 days, while intermittent means 1 cricket every three weeks female_ID       # unique identifier of the females spiX     # the number of spiderlings hatched from X egg sac, e.g., spi1 refers to the number of spiderlings hatched from the first egg sac intervalX         # the time intervals between each time of reproduction, e.g., interval1 refers to the time intervals between the first and second time of egg sac production, unit = days. #### Column Heading Discriptors for **final_dataset_**starved__females_afterfed, it is the reproductive success for females in 5 mg treatment and 120mg treatment from Sheet1):          fe         # unique identifier of the females treatment         # food treatments, these values refer to the approximate body mass of crickets we provided per week, 5mg, 30mg, 60mg, 120mg, and 240mg weight1           #  the weight of the first egg sac after feeding for 5mg feeding females, and the first egg sac from original data for 120mg feeding females, unit = mg number1          #  the number of spiderlings hatched from the first egg sac after feeding for 5mg feeding females, and the first egg sac from original data for 120mg feeding females meanweight1   #  the mean weight of spiderlings from the first egg sac after feeding for 5mg feeding females, and the first egg sac from original data for 120mg feeding females, unit = mg deadeggs1       #  the egg numbers that failed to hatch from these egg sacs #### Column Heading Descriptors for **final_dataset_**rollercoaster:       Fe_ID  # unique identifier of the females Fed_MX         # the female body mass after feeding, X represents the times of feeding events before producing egg sac. Unit = mg M_after_eggX # the female body mass after producing an egg sac, X represents the egg sac number. Unit = mg EggX   # the mass of egg sac, X represents the egg sac number. Unit = mg ### Supplement 1-cricket size #### Column Heading Descriptors for Sheet 1 (short term):       | type | # three categories for crickets, these categories were the standard for visualizing selecting crickets | | :------- | :----------------------------------------------------------------------------------------------------- | | bodymass | # measurement of the cricket, unit = mg | | note | #  the standard deviation of each category. | ### Supplement 2-the first three egg sacs and lifetime reproductive success #### Column Heading Descriptors for Sheet 1 (short term):    | female\_number | # unique identifier of the females | | :-------------------------- | :------------------------------------------------------------------------------------------------------- | | total\_weight\_eggsac\_mass | #  the total weight of all egg sacs produced by the female through lifetime, unit = mg | | total\_number\_spiderling | #  the total number of spiderlings hatched from all the egg sacs produced by the female throughout her lifetime | | eggsac\_mass1 | #  egg sac weight from the first egg sac, unit = mg | | number\_spiderling1 | #  the number of spiderlings hatched from the first egg sac | | eggsac\_mass2 | #  egg sac weight from the second egg sac, unit = mg | | number\_spiderling2 | #  the number of spiderlings hatched from the second egg sac | | eggsac\_mass3 | #  egg sac weight from the third egg sac, unit = mg | | number\_spiderling3 | #  the number of spiderlings hatched from the third egg sac | | totalmass3 | #  the total weight of the first 3 egg sacs, unit = mg | | totalsp3 | #  the number of spiderlings hatched from the first 3 egg sacs | #### Sharing/Access information NA ## Note If a cell is empty, it means no data was collected. ## Code/Software R code will be submitted when the manuscript is accepted.