Salt is notoriously dangerous to land snails; however, some populations of aquatic, freshwater snail have brackish (or a mix of salt and fresh water) water adaptations and live in different parts of a river system. A group of scientists monitored salt concentrations in the habitats of two freshwater snail populations located nearby and recorded the salt level as follows (in ppt, parts per thousand):

Question

Salt is notoriously dangerous to land snails; however, some populations of aquatic, freshwater snail have brackish (or a mix of salt and fresh water) water adaptations and live in different parts of a river system. A group of scientists monitored salt concentrations in the habitats of two freshwater snail populations located nearby and recorded the salt level as follows (in ppt, parts per thousand):

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

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

In 9th grade writing to 3–5 sentences, 1) describe in which population you'd expect to see more adaptations for salt water and 2) explain how such adaptations would become more common in this population.

Answer 1

1) Based on the data provided, population 2 is likely to have more adaptations for salt water. This is because population 2 experienced higher salt concentrations throughout the day compared to population 1.

2) Adaptations for salt water would become more common in population 2 through a process known as natural selection. In this case, individuals within population 2 that possess traits enabling them to tolerate higher salt concentrations have a better chance of surviving and reproducing. These advantageous traits would then be passed on to future generations, gradually increasing the number of individuals with adaptations for salt water in the population. Over time, this would result in a higher proportion of individuals with saltwater adaptations in population 2 compared to population 1.