Critical Thinking - Question 3
Individuals of some species of bony fishes change sex, some to maintain more males than females, others more females than males. What are the advantages and disadvantages of each situation? Are there any advantages and disadvantages in having an equal number of males and females?
In the deep sea finding a mate can be difficult – even harder than finding food therefore being able to change from a male to a female or a female to a male is advantageous for these types of fishes because there would be an increase in reproduction. Deep-sea fishes that are hermaphrodites guarantee the ability to breed. In at least some species of anemone fishes (Amphiprion), all individuals begin as males. Each sea anemone is inhabited by a single large female that mates only with a large, dominant male. If the female disappear or is experimentally removed, her mate changes into a female and the largest of the non-breeding males becomes the new dominant male. Males of some wrasses form harems of many females. If the male disappears, the largest dominant female immediately begins to act like a male and within a relatively short period of time changes color and transforms into one that is capable of producing sperm. A variation of hermaphroditism among fishes is sex reversal, or sequential hermaphroditism, in which individuals begin life as males but change to females (protandry), or females change into males (protogyny). These changes are controlled by sex hormones but triggered by social cues such as the absence of a dominant male. I believe that there are neither advantages nor disadvantages in having an equal number of males and females since protandry and protogyny are present within these fishes. The way I understand it, we will never run out of fishes that are hermaphrodites.
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