Data from: Fighting through the heat: How male aggression influences demography under recurrent heatwaves

Sexual selection is a potent evolutionary force that can enhance
adaptation and reduce mutational load, while simultaneously reducing
survival, or cause sexual conflict that reduces fitness for one or both
sexes. Many populations today face not only gradual environmental changes
but also extreme, short-term stress events. The combined effects of sexual
and environmental selection on population demography during and after such
events remain poorly understood, even though such combined effects could
be crucial for the persistence of small, endangered populations under
climate change. This dataset derives from a multi-generational
experimental evolution study investigating how sexual selection interacts
with thermal stress to shape population demography in the male-dimorphic
soil mite Sancassania berlesei. It includes detailed generational
records from 42 populations subjected to a factorial design manipulating
sexual selection intensity (via pheromone-induced morph suppression) and
exposure to recurrent heatwaves. Key variables include juvenile counts,
adult survival before and after heat stress, sex ratios, male morph
frequencies (fighter vs. scrambler), and extinction events, recorded over
eight generations.The dataset enables fine-scale analysis of how sexually
selected traits and environmental stressors jointly affect survival,
sex-specific mortality, and extinction risk. It has strong reuse potential
for researchers studying eco-evolutionary dynamics, sexual selection,
inbreeding, and climate resilience in small populations. All data were
collected under standardized laboratory conditions, with no human or
vertebrate subjects involved.