Salt is dangerous to land snails. It will rapidly kill them. However, some populations of aquatic, freshwater snail have adapatations that allow them to live in a mix of salt and fresh water. This allows them to live in different parts of a river system. A group of scientists monitored salt concentrations in the habitats of two freshwater snail populations. They recorded the salt level as follows (in ppt, parts per thousand):

Question

Salt is dangerous to land snails. It will rapidly kill them. However, some populations of aquatic, freshwater snail have adapatations that allow them to live in a mix of salt and fresh water.  This allows them to live in different parts of a river system. A group of scientists monitored salt concentrations in the habitats of two freshwater snail populations. They recorded the salt level as follows (in ppt, parts per thousand):

Location 1 (Day 1):  0.1 ppt (morning), 0.0 ppt (afternoon), 0.1 ppt (evening)

Location 2 (Day 1):  0.3 ppt (morning), 0.5 ppt (afternoon), 0.2 ppt (evening)

In 3–5 sentences, describe in which population you'd expect to see more adaptations for salt water. Make sure to also explain how such adaptations would become more common in this population.

GPT-4o mini · Answer

In Location 2, where the salt concentrations are consistently higher (0.3 to 0.5 ppt), I would expect to see more adaptations for saltwater tolerance among the freshwater snail population. These adaptations could include physiological modifications that allow them to regulate osmotic pressure and excrete excess salt, as well as behavioral changes to seek out optimal salinity levels. Over time, individuals with better adaptations for handling higher salt levels would likely have a survival advantage in this environment, leading to increased reproductive success and the passing of these beneficial traits to future generations, thus making such adaptations more common in the population.