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: Adaptation traits contribute to individual fitness and to the evolution of animal genetic resources. 
Sentence2: Behaviors can improve the evolution of animal genetic resources.
animal

Sentence1: faulting of rock in Earth 's crust causes earthquakes. 
Sentence2: fault movement forms earthquakes.
earthquakes

Sentence1: Fungi have special structures for penetrating a host. 
Sentence2: molds have special structures for penetrating a host.

have