The Sri Lankan Elephant lives in Asia and India in very lush environments with lots of rain and an average temperature of 70 degrees fahrenheit.
The elephants environment is becoming too warm and has little rainfall, so they migrate to their old lake. Due to the extreme drought, however, the lake has dried up.
20,000 years later
Due to the extended drought and extreme tempurature change, the elephants have been forced to adapt to their new environment. They are now smaller, their blood cells are smaller and more elastic in order to hold more water, and their skin is lighter in order to absorb less heat. They also travel in smaller herds so that they don't have to share as much water.
40,000 years later
Smaller bodies are becoming more common among the population, along with smaller blood cells and color difference. The lighter color absorbs less heat than the darker color.
60,000 years later
The elephants are now living in an oasis. Natural selection is causing the smaller elephants to reject mating with the larger ones, and they begin to die off.
80.000 years later
The entire population of Sri Lankan elephants is smaller in both body and herd size, and are now lighter to be better adapted to the extended drought and extreme heat. The elephants have stopped migrating and have settled in one area where there is water for the herd.