Salt is dangerous to land snails. It will rapidly kill them. However, some populations of aquatic, freshwater snail have adaptations 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 adaptations 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

I would expect to see more adaptations for saltwater in the population at Location 2, given its higher average salt concentrations compared to Location 1. The consistent exposure to higher salt levels (0.3 to 0.5 ppt) would likely exert selective pressure on the snails in Location 2, favoring individuals with traits that enable them to better tolerate or regulate salt. Over time, those snails that survive and reproduce due to these advantageous adaptations would pass those traits to their offspring, leading to an increased prevalence of salt-tolerant adaptations in the population.