Haploid selection and adaptation|Fish (Danio rerio)Selection among sperm may be an effective way to weed out bad, and favour good genes.
I will explore whether (and how) haploid selection among sperm can aid adaptation to a changing environment. |
Adaptive thermal plasticity|Beetles (Tribolium castaneum)Phenotypic plasticity can buffer against changes that are too fast to track using genetic adaptation. If males and females can anticipate the environment in which their gametes (sperm and eggs) have to function, they may gain fitness by producing gametes whose performance is maximised in that environment.
My colleague Ram Vasudeva found that males produce shorter sperm, and females produce larger eggs when developing at higher temperatures, and that both sperm and eggs do better when their performance temperature matches the temperature experienced during gametogenesis. |
The evolution of polyandry|Flies (Drosophila pseudoobscura)Polyandry (females mating with multiple males) is probably more common than single-male mating. Many questions about what drives and maintains variation between species, populations and individuals remain unresolved (Taylor et al. 2014). Through experimental evolution of populations that I initiated with different compositions of flies with a genetic propensity for high or low levels of polyandry, I tested whether polyandry would evolve towards an externally derived "optimal" frequency.
It did not. Polyandry stayed close to its starting frequency, both in high and low polyandry populations, indicating there was no selective advantage or disadvantage of polyandry in this context. However, females show behavioural plasticity in their mating strategies, flexibly using polyandry to safeguard their reproductive fitness when some males are sterilised by heat-exposure. |
Sexual selection and selfish genes|Mice (Mus domesticus)Meiotic drivers are selfish genetic elements that cheat during sexual reproduction to get more than their fair 50% representation among offspring (see e.g. Lindholm et al. 2016). A meiotic driver in house mice gets inherited to 90% of offspring through males, but is associated with fitness costs to the rest of the genome. So the rest of the genome should evolve counter-adaptations to reduce the success of the driver. In my PhD, I investigated how female choice and female multiple mating (polyandry) might keep the meiotic driver at bay.
Females did not show any signs of avoiding these males prior to mating, but female mice are polyandrous, and males carrying the driver had strongly reduced paternity success when their sperm competed with the sperm of other males. Hence, polyandry could evolve as a counter-strategy against meiotic drive. |
Secondary contact zones|Voles (Microtus arvalis)When populations separated for a long time by geographical barriers come into secondary contact, they may exhibit (partial) reproductive isolation, depending on the extent of genetic differentiation. During ice ages, common voles have repeatedly been separated by glaciers in the alps, and have come into secondary contact when the ice retreated. For my MSc, I tested genetic markers exclusively inherited through males (Y chromosome) or females (mtDNA), respectively, to look for a genetic signature of partial reproductive isolation.
I found that contact zones were narrow for both markers, but that the male one was much more narrow, and was displaced relative to the maternally inherited one, suggesting asymmetric partial reproductive isolation. |