Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: Courtship is behavior that is intended to attract a mate. 
Fact 2: Almost all animals display colors to attract a mate or to scare off a predator.
Courtship can be manifested by displays of color.

Fact 1: killing microorganisms in food can be used to extend the shelf life of that food. 
Fact 2: Irradiation kills microorganisms that spoil food.
Irradiating food can extend shelf life by removing microorganisms.

Fact 1: Phylogeny is the evolutionary history of a group of related organisms. 
Fact 2: Classification can be based on phylogeny.

classification can be based in the evolutionary history of a group of related organisms.