# The Effect of Differing Levels of Intrasexual and Intersexual Selection on Survival and Reproduction Under a Heatwave

## TL;DR

The study explores how mating behaviors affect beetle survival and reproduction during heatwaves, finding that certain mating conditions reduce negative impacts.

## Contribution

The paper investigates how varying levels of intrasexual and intersexual selection moderate fitness responses to heatwaves in a natural population.

## Key findings

- Reproductive fitness decreased under a heatwave in the polyandry/low male competition treatment.
- Monogamy and male competition treatments showed better reproductive outcomes during heatwaves.
- Intrasexual and intersexual selection levels can moderate the effects of heatwaves on wild species.

## Abstract

Heatwaves are set to become more common due to climate change, and the potential of heatwaves to damage a species' populations is becoming more apparent. One way heatwaves can affect reproduction is by changing the dynamics of precopulatory mating behaviours, which can detrimentally impact individuals' survival and reproductive success. However, little work has been done to investigate how different levels of intrasexual and intersexual selection in precopulatory behaviours, such as male–male competition or female‐mate choice, modulate fitness responses to heatwave. Here we investigate how differing levels of male competition and female choice impact survival and reproductive success when a heatwave event occurs, using cool‐adapted Scottish populations of the burying beetle
Nicrophorus vespilloides
as a model system. We implemented three treatments for precopulatory conditions: monogamy (one male, one female, no male–male competition), polyandry with male competition (one female, two males, where males and females could freely interact), and polyandry with low male competition (one female, two males, where males could not interact with each other or the female freely). We then subjected the beetles to a heatwave event (3 days at 25°C) at the time of mating. We found that reproductive fitness decreased under a heatwave in the polyandry/low male competition treatment, compared to both the monogamy and the male competition treatments. Our results indicate that differing levels of intrasexual and intersexual selection can moderate the detrimental effects of heatwaves in wild species.

Precopulatory mating behaviour, are important for fitness and can be disrupted by heatwave's. Here we assess how differing levels of intrasexual and intrasexual selection in precopulatory mating behaviours impacts fitness responses to heatwaves. We find that the likelihood of having a brood is impacted by differences in intrasexual and intersexual selection in response to a heatwave.