DOI: 10.5061/dryad.dbrv15dwx
title: Multimodal and multifunctional signaling? – web reduction courtship behavior in a North American population of the false black widow spider

description: Males of widow spiders courting on the web of females engage in web
 reduction behavior which entails excising a section of the web, bundling
 it up, and wrapping it with their silk. Males of the false black widow
 spider, Steatoda grossa , in European populations also produce
 stridulatory courtship sound which has not yet been studied in their
 invaded North American range. Working with a North American population of
 S. grossa , we tested the hypotheses that (1) web reduction by males
 renders webs less attractive to rival males; (2) deposition of silk by
 courting males has an inter-sexual (male-female) signal function that
 enhances their likelihood of copulation; and (3) stridulatory sound is a
 courtship signal of males. Testing anemotactic attraction of males in
 Y-tube olfactometer experiments revealed that reduced webs (indicative of
 a mated female) and intact webs (indicative of a virgin female) were
 equally attractive to males. Recording courtship behavior of males with
 either functional (silk-releasing) spinnerets or spinnerets experimentally
 occluded on the web of virgin females showed that males with functional
 spinnerets were more likely to copulate with the female they courted.
 Although males possess the stridulatory apparatus to produce courtship
 sound, they did not stridulate when courting or copulating on the web of
 females. Our data support the conclusion that web reduction behavior of S.
 grossa males in their invaded North American range has no long-range
 effect on mate seeking males. Instead, web reduction behavior has an
 inter-sexual signaling function that seems to be linked to functional
 spinnerets of the courting male. The signal produced by a male likely
 entails a volatile silk-borne pheromone, but may also embody a gauge of
 his endurance (the amount of time he engages in web reduction causing web
 vibrations).
description: File Descriptions:
 --analysis_exps_1-5,7.R--<br> This file contains the R
 code, for all statistical analyses of experiments 1-5,7, and well as the
 code to generate Fig. 3. The metadata for "exp_1.csv - exp_5.csv,
 exp_7.csv" are also fully described in this file.
 --exp_1.csv - exp_4.csv--<br> These files contain the
 response data from the y-tube olfactory experiments (exp. 1-4) testing the
 effect of web reduction on the response of male false black widow spiders
 to female webs. --exp_5.csv--<br> This file
 contains the behavioural responses of male and female false black widow
 spiders from mating trials in which half of the males had their
 spinneretes occluded with super glue.
 --exp_7.csv--<br> This file contains the durations of
 upward and downward abdominal movement of male false black widow spiders
 from high speed video recordings of mating trials.
 --weight and size regression.R--<br> This file contains the
 R code used to fit a regression of weight and tibial length in false black
 widow spider males and females and calculate a "condition index"
 (residuals) for each spider. This file also contains the code necessary to
 generate Fig. S2. --(fe)male weights and
 sizes.csv--<br> Weight and tibial length measurements of the entire
 pool of either male or female spiders used to calculate the
 "condition index" (weight and tibial length residuals). Metadata
 descriptions are the same as those described in "analysis exps
 1-4.R".