Data from: No support for cryptic choice by ovarian fluid in an external fertilizer

Whether the ovarian fluid represents a selective environment influencing
cryptic female choice was tested using an external fertilizer experiencing
intense sperm competition and large effects of ovarian fluid on sperm
swimming behaviour - the Arctic charr (Salvelinus alpinus). We physically
separated the ovarian fluid from the eggs of reproductively active females
and reintroduced either their own ovarian fluid or fluid from another
female to the eggs. The eggs were then fertilized in vitro in a replicated
split-brood design with sperm from two males under synchronized sperm
competition trials, while also measuring sperm velocity of the individual
males in the individual ovarian fluids. We found large effects of males,
but no effect of females (i.e., eggs) on paternity, determined from
microsatellites. More important, we found no effect of ovarian fluid
treatments on the relative paternity of the two competing males in each
pair. This experimental setup does not provide support for the hypothesis
that ovarian fluid plays an important role as medium for cryptic female
choice in charr. Power-analyses revealed that our sample size is large
enough to detect medium sized changes in relative paternity (medium-sized
effect-sizes), but not large enough to detect small changes in relative
paternity. More studies are needed before a conclusion can be drawn about
ovarian fluid’s potential influence on paternity under sperm competition -
even in charr.