Sexual selection, or nonrandom mating, is an important factor for evolution. In most animal species, females choose the mating partners (female choice) with the help of different criteria. However, mating with multiple males may lead to other selection processes inside the female body. Among the most widely-spread processes of such kind are sperm competition and cryptic female choice. Cryptic female choice means the ability of females to decide which sperm (for example, of male A, B or C) will be preferentially used to fertilize the eggs. In my project, I investigate cryptic female choice in the field grasshopper Chorthippus biguttulus using different mating experiments and genetic analyses of offspring. The main focus lies on the possible influence of male attractiveness and the influence of relatedness between males and females.
The question of my research project regards to adaptive conformance to social niches and its proximate mechanisms. Although Zebra finches (Taeniopygia guttata) are known to be monogamous and conduct bipaternal care, extra-pair copulation occurs occasionally. Hence, male individuals face a trade-off securing fertilisations versus parental investment in response to the extent of sexual competition. In our project, we want to investigate how individual variation in sexual competition generates individual variation, and covariation, in both competitive traits and parenting behaviour. Therefore, I use an experimental setup consisting two conditions that vary in sperm competition risk (SCR), i.e. the presence/absence of an ejaculate rival. For my project, I investigate the plasticity of the behavioural phenotype in pre-and postcopulatory competitiveness and male parental care in response to SCR by using behavioural observations as well as endocrinological measurements (subproject A). This work is strongly connected to subproject B, which evaluates ejaculate traits and transcriptomic mechanisms in the model system.