Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Mutations are essential for evolution to occur. 
Sentence2: Genes are altered for evolution to occur.
evolution

Sentence1: Mammalian predators include the coyote and bobcat. 
Sentence2: a coyote's teeth is important for digestion.
coyote

Sentence1: Zooplankton are tiny animals that feed on phytoplankton. 
Sentence2: Fish and other animals eat tiny animals that feed on phytoplankton.

animals