Question

An ecosystem now receives far less rain than it used to. The weather also became drier and hotter. Over time, plants with structures that helped them to conserve water became more prevalent than plants that didn’t have those structures. From this information, we can conclude that the plants developed because of

Answer 1

The plants of this ecosystem were influenced by the change of abiotic factors (climate). 
The plants who had these specialized structures that have helped them conserve water and adapt to these new environmental conditions were more successful, and left more offspring.After several generations, the specialized plants became more prevalent.
Since there was a selection of successful individuals trough generations, we can conclude that this was due to the working of the evolutionary mechanism called the natural selection.