A species of bird has slight variations in its beak size and shape. Some individuals with bigger beaks are better at craking seeds. Some individuals with narrower beaks are better at hunting for bugs. An invasive species is introduced that hunts all of the bug population, wiping out the food source for the birds, so all they are left with is seeds.
This change in food availability will likely have a significant impact on the bird population. The individuals with narrower beaks that were better at hunting for bugs will struggle to find enough food, as their primary food source has been eliminated by the invasive species.
On the other hand, the individuals with bigger beaks that were better at cracking seeds will have a better chance of survival, as they are able to utilize the remaining food source. Over time, this may lead to a shift in the population dynamics, with individuals with smaller beaks being at a disadvantage and potentially facing a decline in numbers.
The invasive species has disrupted the natural balance of the ecosystem, leading to changes in the behavior and survival rates of the bird population. This highlights the importance of understanding and managing invasive species to protect the delicate balance of ecosystems and the survival of native species.