Several ecology students were tracking the population ranges of two species of squirrels that live in the cascade range of oregon. these students noted that when both species of squirrels were present in a region, species a could be found from sea level to about 900 feet above sea level, and species b could be found from about 900 feet to 1,500 feet above sea level. however, when species b was found alone, it had a range of about 500 feet to 1,500 feet above sea level. this is an example of

The correct answer is competitive exclusion.

Explanation:

According to the principle of competitive exclusion, the two species, which compete for the exact identical resources cannot coexist stably. Of these two competitors, one will always exhibit a slight advantage over the other, which results in the extinction of the second competitor in the prolonged time.  

It can also result in an evolutionary shift of the inferior competitor towards a distinct ecological niche. As an outcome, the competing associated species usually evolve differentiating features in the regions where they both coexist. This helps in mate identification, thus, sustaining the superiority of each species in exploiting somewhat distinct ecological niches.  

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.