Final answer:
An animal that changes sex from female to male after the dominant male's death is an example of environmental sex determination, which differs from genetic sex determination and is not related to frequency-dependent selection.
Step-by-step explanation:
The phenomenon where an animal begins its life as a female and changes sex to become male after the dominant male dies is known as environmental sex determination. This is not an example of frequency-dependent selection, which includes forms such as positive frequency-dependent selection (favoring common phenotypes) or negative frequency-dependent selection (favoring rare phenotypes). Instead, it is a type of sex determination influenced by environmental factors rather than fixed by genetics at conception. Genetic sex determination is when sex is determined by chromosomes at the time of fertilization, contrasting with the described scenario.
In the case mentioned in the question, the change of sex may be influenced by social factors within the animal group, such as the absence of a dominant male which triggers the largest or most dominant female to become male. This is characteristic of some fish species and other marine animals and is a form of environmental sex determination, more specifically social cues, rather than frequency-dependent or genetic sex determination.