Talk  D21SY25RT15:45R7

Parent-gamete proximity and its consequences for the evolution of sex roles

Author(s): Henshaw JM, Kokko H, Jennions MD, Marshall DJ

Summary:

Why do some female marine animals release their eggs into the water to be fertilised, while others retain them on, or inside, their bodies? Why do terrestrial plants disperse pollen but not ovules, and why do most terrestrial animals hold onto both sperm and eggs until they find a mate? Sex role research has largely overlooked the significance of where gametes are located when fertilisation occurs. Parent-gamete proximity during fertilisation is not only a basic difference between the sexes in many species; it is also essential to the evolution of parental care and most forms of mate choice. I explore the evolutionary logic behind gamete release and retention using mathematical models. I focus particularly on marine invertebrates, in which evolutionary changes in these behaviours are common. Along the way, I provide a new explanation for why egg retention, small body size, and large egg size are correlated in sessile marine invertebrates. I also explain why there are no species in which males retain their gametes while females release them.

Video