In the second hour, "Natural Selection" (10:00-11:00 p.m.), some rocky and intriguing developments confront the crew as they learn to adjust to life on board the Antares, as they find that some past choices, combined with an unknown element in the ship's mysterious Storage Pod 4, lead to a complex web of dreams, desires and illusions that result in a life-threatening crisis.

"Natural Selection" was directed by Peter Howitt and written by James Parriott.