Translation to spanish of the term FITNESS

[caosingaia]

Hi everybody,

Nowadays I am translating a text about sexual selection and mating systems, but I have not found the equivalence to the term FITNESS in Spanish. Can anybody help me, please?

The fragment of the text in which the term is used is the following:

"Original investigations of sperm competition focused on traits of sperm quality and morphology that increase REPRODUCTIVE FITNESS"

Thank you.

My e-mail is: [email protected]