Principal 3: Different survival and reproduction
Big humps help the camel carry more water which helps them walk further
Principle 4: Change in Gene pool
Smaller hump will constantly need more water. They will finish the water and camel will end up dying if there is no water.
The dark brown camel because they have bigger humps that help carry more water so they don't constantly have to be stopping to get water and when the water run out they have enough water to go look for more water.
Most camels will have big humps to help them contain more water