Skewed paternity and sex allocation in hermaphroditic plants and animals

Models predict a reduced allocation to sperm when females preferentially us e one of two males' sperm and the males do not know who is favoured. An ana logous discounting occurs in plants when their paternity success is skewed by random, non-heritable factors such as location in the population and pol linator behaviour. We present a model that shows that skewed paternity call affect the sex allocation of hermaphrodites, that is it leads to a female- biased investment. The model highlights the close links between local mate competition and sperm competition. We use paternity data front Ficus in ord er to illustrate that skews in paternity success can lead to a high degree of sibling gamete competition in all apparently open breeding system. Since skews in paternity arc ubiquitous in hermaphroditic plants and animals the se findings should apply broadly.