Question

a biologist studying a desert ecosystem observes that the population of a lizard species increases following a particularly hot, dry period that causes a snake species to decline. What could the biologists hypothesize about the roles of theses two species?

A:The lizard preys on the snake
B:The lizard is a parasite of the snake
C:The snake and the lizard use the same limiting recourse
D:The snake is a keystone species in the ecosystem

Please help me its for a huge test and I need the answer!

Answer 1

The answer is D. The snake is a keystone species in the ecosystem.

Answer 2

Based on the description of events, being that the lizard population appears to increase as soon as the snake population decreases, it appears that the snakes prey on the lizards. This suggests that the snake is a keystone species. A keystone species is one that has a dramatic effect on maintaining the balance of an ecosystem. As soon as the snake population decreases, major changes occur to the ecosystem, such as the lizard population increasing.

Therefore, the answer is D: The snake is a keystone species in the ecosystem.