Mating strategies in changing environments

Background

Sexual selection is a potent force that drives rapid evolutionary change. Sexual selection often continues after mating, when females mate with multiple males, generating sperm competition and cryptic female choice (collectively "post-copulatory sexual selection" PCSS). PCSS favours males that strategically allocate ejaculates at mating.

E.g., to achieve a higher paternity share, males may boost sperm transfer when they sense a heightened risk that their mates will copulate with rival males. Understanding ejaculate strategies and their role in PCSS is a major goal in the field. However, most studies are conducted under benign lab conditions.

In nature, animals will experience stressors, e.g. food shortages, disease outbreaks and adverse weather conditions. These stresses have the potential to alter what males transfer at mating, and how females respond, shaping optimal strategies and the operation of PCSS. Objectives

Overall Aim: Examine the roles of environmental stressors on male ejaculate allocation and the consequences for PCSS in Drosophila fruit flies.

Objectives: in both sexes, to test the effects on male sperm and seminal fluid allocation at mating, and resulting paternity outcomes, of a) nutritional restriction b) infections c) temperature stress Novelty and Timeliness

We currently understand that PCSS is widespread. However, a common disconnect is the link between male strategies, and the resulting paternity outcomes, which are either not measured, or results are inconsistent. Our idea is that the unnaturally benign conditions commonly used in lab studies mask adaptations that would be beneficial in nature.

What is needed now is to test whether exposure to stressors (in both sexes) will reveal a stronger link between what males transfer, and the paternity share they achieve. This is what this project will do, forging a novel step forward for the field of sexual selection, and linking it with global change.