Answer:
natural selection
Explanation:
There are many processes through which evolution can occur like migration, mutation, genetic drift and natural selection. However, one of the most important triggering factor for evolution is natural selection
.
What is natural selection:
In very simple words it can be considered as the process through which organisms that are better able to adapt to their surrounding environmental conditions survive and thrive, thereby they reproduce and transfer their characteristics in offspring, but those that have less ability to adapt to environmental conditions, tend to become less in number and ultimately eliminate.
How natural selection leads to evolution:
Now to understand how natural selection leads to evolution, we will take example of a population of beetles, some are brown and some are green in color. Now environment has limited capacity and it cannot support the survival of each and every population.
Here what happens is the green beetles are vulnerable to attack by birds because their color is visible to birds but brown beetles are less visible. What will happen that green beetles will be all eaten by birds and brown will keep surviving.
Now years later, beetles will have only brown color because evolution occurred and only fittest ones survive.
This is how natural selection leads to evolution.
Hope it helps!
