Cryptic female choice and gamete-mediated paternal effects in the context of interspecific hybridization

Abstract

The environment in which fertilization takes place can have significant effects on paternity and offspring development. Through cryptic female choice, females can bias paternity to benefit a particular male and “choose” the father of her clutch. These processes might affect offspring development through non-genetic gamete-mediated paternal effects. I chose to examine the impact of cryptic female choice on paternity and offspring development in an externally fertilizing taxa that readily hybridizes, Salmoninae. Hybridization can represent a bad outcome for females with far-reaching effects on offspring phenotype and development. Females can reduce hybridization through conspecific sperm preference, a mechanism of cryptic female choice. What is unknown is the magnitude of conspecific sperm preference and the extent of gamete-mediated parental effects in our study populations and how these effects change in relation to hybridization. Following previous work done with other populations of salmonids, I expected to find evidence for strong conspecific sperm preference and paternal effects. Here, I examined conspecific sperm preference in three species, native brook char (Salvelinus fontinalis) and Atlantic salmon (Salmo salar), and introduced and invasive brown trout (Salmo trutta) and found that while ovarian fluid influenced sperm behavior, this effect did not differ among species. However, while hybridization between Atlantic salmon and brown trout significantly affected offspring development, paternal effects derived from the fertilization environment did not. This implies that females can alter paternity through cryptic female choice without consequences to the offspring. More research is needed in this and other salmonid species and populations to determine if these effects are present across salmonids.