Certain species of fish such as guppy, mosquitofishes, mollies or swordtails lay their eggs for external fertilisation. Selecting a partner with genetically stronger "qualities" will avoid wasting eggs.
Bart Pollux and his colleagues show that the evolution of the placenta is associated with large mixed-paternity litters resulting from females mating with multiple males. Males become less showy as they do not need to attract a mate; moreover, males become smaller and have longer genitalia that allow them to be sneaky or coercive with copulation, thereby circumventing female choice. These adaptions increase male reproductive success and decrease the females risk of putting all of her eggs in a genetically inferior basket.
Bart Pollux received an individual grant from the Marie Skodowska-Curie actions, an EU programme funding researcher's career development and mobility.
Read the Nature article