Investigating plasticity in ejaculate traits
Behavioural plasticity allows animals to adjust their behaviour to rapid changes in the environment. In the context of sexual reproduction the socio-sexual environment can change very rapidly, altering for example the encounter rates among individuals and consequently the intensity of competition between males. The extent to which males plastically adjust their mating strategies in response to such changes remains a very intriguing question to answer, with important fitness consequences that are to be explored.
Field crickets are model organisms for testing these ideas, as they are known to respond to socio-sexual cues by modulating their investment in ejaculate traits, which ultimately play a major role in winning competitive fertilization interactions. Ejaculates are transferred to the female during copulation through a ‘sperm package’ (the spermatophore) which allows straightforward sample collection and subsequent measures of sperm traits, such as sperm numbers and sperm viability (i.e. the proportion of live cells in the ejaculate). Furthermore, crickets are easily raised in laboratory conditions with large experimental opportunities for manipulating the social environment (i.e. varying male:female sex ratios, population density, or male-male agonistic encounters).
We offer access to our laboratory population of the species Gryllus bimaculatus to explore such ideas.