Evolution and population dynamics - Passage 2.

Problem

Russian environmentalists were in tears this morning when their three month-long protest against the construction of a highway through Moscow’s Khimki forest was disregarded.
This new highway, which was recently approved for construction, will cut right through the heart of Moscow’s only forest, and will require almost 10 square kilometers of clear cutting to make room for the development.
“It’s like taking a knife to your own face to try and look prettier,” said Artur Savrasov, a 24 year-old Moscow University graduate.
“I don’t think the government realizes the impact this will decision have on the Moscow we will leave [to] our descendents,” said Viktor Bogdanov, leader of the protest.
Many species of animals will no longer have adequate food access as most of the food sources in Khimki forest are localized to certain areas found only on one side of the future highway.
It is possible that the construction of this highway will cause allopatric speciation to occur. Allopatric speciation is the process that drives two groups of animals from the same species to evolve into different species following the introduction of a physical barrier separating the two.
While this may allow for a more diverse population of creatures in the forest, many environmentalists believe that populations on either side of the highway will become too small, which may result in many of the species native to Khimki forest, like the snowy owl, becoming endangered.
Construction is said to begin in early 2012.
Two populations of snowy owl become separated by the highway. Which form of pre-zygotic reproductive isolation prevents the two populations from mating?
Please choose from one of the following options.
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