Overall, Natural selection exists in many species and occurs over millions of years. Elephants have adapted from a pig-sized creature, changing its size, trunks and adapting to the warmer climates and different habitats.
During evolution, elephants lost their thick fur due to climate change an warming climates and developed a thicker skin. This allowed them to adapt in hot temperatures. They are able to reduce and regulate their body temperature and that adaptation of larger ears is so they are able to cool down.
Humans taking away their habitats, such as cutting down rainforrests has forced them to move and adapt to different habitats and climates. Therefore, not all species were able to adapt.
Therefore, only leaving the African and Asians Elephants as the last of their species.