His interests lie in how life survives at the extremes, and according to Sowell the bitter existence of trees at their high-elevation limits and life in the desert's desiccating heat are both remarkable examples of survival.
(His interests; lie; in how life survives at the extremes) (life; survives; L:at the extremes)
His interests life
lie survives
in how life survives at the extremes
L:at the extremes