20 POINTS AND BRAINLIEST

1.) answer: The correct answer is They share the same niche.

Niche can be defined as a specific area for an organism where it inhabits and shows interactions with environment for their survival in terms of resources. If two species share the same niche then they will have competitive relationship for sometime.

It is because according to the competitive exclusion principle, it is not possible for two species to share the same niche a longer duration of time. Thus, out of these two competitive species one will survive while the other specie will migrate or eliminate.

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.

3.) I believe the answer is B!

Explanation: