Original: Wagner devoted three years ( 1836 â '' 1839 ) to the exploration of Algiers : it was here that he made important observations in natural history , which he later supplemented and developed : that geographical isolation could play a key role in speciation .
Simplified: Wagner devoted three years ( 1836 â '' 1839 ) to the exploration of Algiers . It was there that he made an important discovery in natural history , which he later developed .