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: Gene flow occurs when individuals move into or out of a population. 
Fact 2: Geographic subdivision decreases gene flow.
Geographic subdivision decreases how fast individuals move into or out of a population.

Fact 1: the surface of a beach is formed by mechanical weathering. 
Fact 2: Beaches and Sand Dunes Dunes are accumulations of sand blown from the beach by the wind.
sand formations are formed by wind.

Fact 1: a telephone is used for communication by humans over long distances. 
Fact 2: Nokia, the world's largest mobile telephone manufacturer, wants software engineers.

nokia is used for communication by humans over long distances.