Two centuries ago, Tufe Peninsula became separated from the mainland, isolating on the newly formed Tufe Island a population of Turfil sunflowers  This population' s descendants grow to be, on average, 40 centimeters shorter than Turfil sunflowers found on the mainland  Tufe Island is significantly drier than Tufe Peninsula was
So the current average height of Tufe' s Turfil sunflowers is undoubtedly at least partially attributable to changes in Tufe' s environmental conditions
The mainland's environment has not changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago.