It all started during a fascinating lecture about sperm competition by Fabrice Helfenstein during my undergraduate studies in Berne, Switzerland. I dived into the fascinating world of sexual selection, with a specific interest for the links between primary and secondary sexual characters. If males can advertise their quality to choosy females, do sexy males also have more competitive sperm, that win the race to the egg? In my bachelor project, I investigated the relationship between sperm traits and their swimming speed and longevity in the house sparrow. One of the main messages of that paper is that there is high variation in sperm morphology between sperm cells produced by the same male. We hypothesized that males may gain in producing a variety of sperm cells with different characteristics when they cannot accurately predict if the female will use it right away or store it for later fertilization.
During my master and PhD projects supervised by Anna Qvarnström , I became interested in the role of pre- and postmating sexual selection in speciation processes, specifically in the context of hybridization. When species that have diverged in allopatry (i.e. when they were geographically isolated) come into secondary contact, they might still be attracted to each other and hybridize (i.e. mating between individuals of two different species). When hybrids suffer from genetic incompatibilities, individuals of both species are expected to become better at recognizing mates of their own species and avoid producing hybrids. Additionally, interactions between their sperm and eggs might prevent fertilization between species. Studying collared and pied flycatchers of the hybrid zone of Öland, I found that hybrid males between the species suffer severe sterility issues and do not seem to be able to produce any functional sperm. Furthermore, I found that on top of diverging in habitat choice and timing of breeding, which makes the two species less likely to hybridize, pied and collared flycatchers seem to differ in their ability to fertilize heterospecific eggs (i.e. eggs of a different species). Female pied flycatchers, which have the highest risk of hybridizing, seem to be able to select against the sperm of collared flycatchers directly in their reproductive tract (a mechanism called cryptic female choice), as these sperm suffer a rapid decline in swimming speed in their cloacafluid.
See my thesis and publication page for more about pre- and postmating sexual selection within species and divergence in physiology (resting metabolic rate) between Ficedula flycatchers and their hybrids. And stay tuned for more details about the molecular mechanisms potentially underlying interactions between their gametes!
Currently in Jenny Boughman’s lab at Michigan State University, I am studying Icelandic sticklebacks and their impressive capacity to adapt to extreme and rapidly changing aquatic environments. We are studying the consequences of adaptation to highly diverging lake ecology on the evolution of sensory systems (vision, smell and mechano-sensory systems) and brain functions. Read more about the project and my first field season in my blogpost for the BEACON center for evolution in action! I am also interested in the impact of the external environment on interactions between male and female gametes.