Answer:
This event is telling the evolution by natural selection. This is the directional selection where most adapted animals will survive. According to Darwin, the new species arise from a single ancestor due to variation.
It had also seen in the Finches. All the new species of Finches came from a pre-existing seed-eating Finch. When the environment was favorable the Finches were herbivore and feed on seeds.
When the number of birds increases, there is a competition between them. Because the food source was limited. To prevent this competition
some of them go for different foods like insects, fruits, etc.
This food habit change also changes their morphology and separate them from their ancestor.
Similar manner, when draught condition occurs, some of the seed-eating birds become carnivore to survive this new climate. As the environmental condition continues for a long time, the number of carnivore animals will increase in number.
Because due to drought conditions, the availability of seed will decrease. Thus the carnivore birds will be more in number and the herbivore birds will gradually eliminate, as they can't cope with the new climate.
