We recently demonstrated that Chinook salmon ovarian fluid, a viscous substance released with eggs during spawning, differentially alters male sperm function in a female-dependent fashion, and thus that females appear to exert cryptic control of male reproductive success.
In many species, females can control fertilisation after mating via behavioural, morphological, and physiological mechanisms – a process called cryptic female choice (CFC). While undoubtedly widespread, it is generally unknown, if and how CFC might be exerted in external fertilisers, where eggs and sperm are shed simultaneously into the surrounding water.
The rationale for this CFC is unknown, but ovarian-fluid-mediated sperm selection may promote favoured genetic combinations that enhance offspring quality.
Using state-of-the-art computer-assisted sperm analysis, competitive fertilisation trials, and genetic-marker-based parentage assignment we will determine if the observed differential sperm function has any impact on male fertilisation success and if so whether there is a genetic basis for the observed CFC.
Our study will provide insight into the proximate and ultimate causes of CFC, a process that has proven notoriously difficult to investigate. In addition our proposal builds research capacity in an area that has important implications for fertility enhancement and control in aquaculture, agriculture, conservation and human health.
Dr Patrice Rosengrave (University of Otago), Prof. Robert Montgomerie (Queens University, Canada), Dr Sheri Johnson (University of Otago), Ms Sara Ferreira (University of Otago), Ms Cornelia Gessner (University of Otago).