The hormone prolactin is found in different species, where it can have different functions.It is required for osmoregulation in freshwater fish, stimulates nesting in certain birds, and stimulates milk production in female mammals.In developing a hypothesis for how this occurred, the most reasonable assumption to make would be that
A) evolutionary modifications changed the structure of the hormone in different species.
B) the gene for prolactin has arisen independently multiple times.
C) the structure of the hormone is highly conserved, and different responses have evolved.
D) different genes have evolved that produce the same hormone.
E) the receptors for prolactin have arisen independently multiple times.

Question

Quizplus · Accepted Answer

The fact that prolactin is found in different species and has different functions suggests that the structure of the hormone itself is highly conserved across species, while different responses have evolved. This is a common phenomenon in evolution, where a single trait or molecule can have multiple functions in different contexts. Additionally, it is unlikely that the gene for prolactin arose independently multiple times, as this would require numerous chance mutations in the same sequence across different species. Similarly, it is unlikely that different genes evolved to produce the same hormone without some level of common ancestry or conservation. Lastly, the receptors for prolactin are likely conserved across species, as they play a critical role in mediating the hormone's effects.

The Hormone Prolactin Is Found in Different Species, Where It