Potential Master's projects

Reduced fertility under heat stress: What are the downstream consequences?

Climate change is causing more extreme temperature fluctuations, including more widespread, longer, and more intense heatwaves. Extreme weather events can have damaging effects on organisms and cause species declines, extinctions, or range shifts across ecosystems. Animals like insects, whose physiology and metabolism are directly linked to their ambient temperature, are particularly affected. For better predictions of population distributions and persistence, we need to know how extreme conditions not only affect the survival of individuals but also their ability to reproduce. For example, there is growing evidence that heat stress can cause infertility in insects (e.g., due to sperm damage), but individuals below the sterility threshold may be affected in their own, but unexplored, way. Using experimental heatwaves at different life stages in our insect model systems (e.g., Drosophila), this project will explore (1) the short- and long-term fertility reduction in exposed individuals, and (2) the health and fertility consequences for their offspring (i.e., transgenerational effects). A Master's student will work alongside a PhD student and conduct their independent research as part of a bigger project.

How do resource quality and distribution shape sexual selection?

The density of individuals can affect the strength of sexual selection through the rate at which individuals encounter potential rivals or mates. The local density can be influenced by the quality and spatial distribution of critical resources. Clumped resources often lead to individual aggregation and thus more encounters of conspecifics. Individuals may thus plastically respond to the different encounter rates. Using two fly species, Drosophila melanogaster and D. prolongata, we will manipulate the resource distribution and quality to explore the effect of local density on social interactions, sexual selection and fitness outcomes. This project will rigorously test foundational theories around the environmental and population-dynamic factors contributing to the evolution and maintenance of mating systems and selection on pre- and postmating sexual traits.

Expression of alternative reproductive tactics (ARTs) relative to social context

Species with intense male-male competition for access to females often show ARTs, with males of lower competitive ability trying to steal mates from courting rivals. In Drosophila prolongata, for example, non-courting males sometimes intercept the female from a courting male. This ART appears to be condition-dependent, but little is known about how the social context might influence its expression. We plan to test how varying local densities and sex ratios influence the expression of interception in D. prolongata in the context of frequency- and density-dependent selection. Evaluating the environmental and social factors promoting the expression of this ART is important to understand the maintenance of phenotypic variation on secondary sexual traits.

Evolution of sex-specific traits and behaviors under biased sex ratios

We are experimentally evolving populations of Drosophila prolongata under varying operational sex ratios (OSRs): female-biased (4:1), control (1:1), and male-biased (1:2 and 1:4). There are many interesting MSc projects that could compare how reproductive traits and behaviors evolve differently under different OSRs. Some potential topics are:

• Courtship and aggression behavior
• Male and female choosiness
• Territoriality and resource monopolization
• Female remating behavior and fecundity
• Female tolerance to harm through mating
• Expression of alternative reproductive tactics
• Male investment in pre- and postcopulatory sexual traits

Condition dependence of male courtship

Males developing under nutritional stress have fewer resources to invest as adults, which can affect their mating success and ultimately their fitness. Using well-studied genetic lines of Drosophila melanogaster, we will test how food stress during larval development affects male wing morphology. Since the wings play a critical role in courtship (including song production), we will further examine how condition-dependent wing morphology influences courtship song characteristics and ultimately male mating success.