10.5061/DRYAD.HMGQNK9J6
Tuni, Cristina
0000-0002-7190-1143
Ludwig-Maximilians-Universität München
Heimerl, Daniel
Ludwig-Maximilians-Universität München
Dudová, Pavla
Czech Academy of Sciences
Wacker, Karoline
Ludwig-Maximilians-Universität München
Schenkel, Elisa
Ludwig-Maximilians-Universität München
Despréaux, Garance
0000-0002-7190-1143
Ludwig-Maximilians-Universität München
Effects of biases in adult sex ratio and male body condition on the
alternative reproductive tactics of a gift-giving spider
Dryad
dataset
2021
2021-11-24T00:00:00Z
2021-11-24T00:00:00Z
en
296172 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
This dataset contains raw data from the manuscript entitled "Adult
sex ratio and male body condition affect alternative reproductive tactics
in a spider", from Daniel Heimerl, Pavla Dudová, Karoline Wacker,
Elisa Schenkel, Garance Despréaux, Cristina Tuni, accepted for publication
in the journal Behavioral Ecology, The study investigates how biases in
adult sex ratios can affect mating tactics in a spider. Sex ratio
variation can alter the intensity of sexual selection by enhancing
competition for mates. Under intense competition males increase their
investment in behaviors to outcompete rivals (e.g., fighting). Yet, given
that in male-biased environments mating opportunities are rare males may
alternatively reduce costly courtship and/or adopt alternative
reproductive tactics (ARTs). Males of the spider Pisaura mirabilis adopt
different mating tactics, offering females genuine nuptial gifts (prey),
nutritionally worthless gifts (prey leftovers) or no gifts. To test
whether behavioral shifts between gift tactics are triggered by changes in
the competitive environment, we established replicate spider populations
under natural conditions (field enclosures) at varying adult sex ratios
(male-biased, female-biased and equal) and sampled gift tactics (no gift,
genuine and worthless gifts) repeatedly over time. We additionally
explored how male individual traits, such as body size and condition,
affect the expression of ARTs. In male-biased populations males produced
more gifts but of low quality, suggesting competition to trigger increased
mating effort to ensure mate acquisition and fertilizations, but through a
worthless gift tactic. Production of gifts and of genuine gifts was
favored by high body condition, pointing to energetic limitations as being
central for male reproductive capacity. We hence highlight two co-existing
mechanisms at play to explain ARTs in this system, the competitive social
environment where expression of gift tactics is based on optimal-decision
making to overcome competition, and a conditional strategy linked to the
individual’s energetic state.
We established replicate spider populations inside enclosures housed on
the Ludwig Maximilians University's Biocenter. While keeping
densities constant we established three adult sex ratios (male-biased,
female-biased, equal sex ratio). We inspected each enclosure at regular
intervals over the course of the breeding season,
and scored occurrence and quality of male nuptial gifts. This was done, by
scoring whether individually marked males were carrying a silk wrapped
prey and by collecting animals to measure gift weight as an indication of
quality, and male body mass to estimate male condition. Data was processed
by generalized linear mixed effects models (GLMM) using R.
The readme file contains an explanation for each of the variables in the
dataset, including measurement units. Information on how the measurements
were taken can be found in the associated manuscript referenced above.