Aparticular species of sea bird underwent a genetic mutation that resulted in big beaks. the larger size of beaks the bird to break open clams and other mollusks for food. it also them defend themselves against predators. after many generations, almost all of the organisms in the population have big beaks. tor which two reasons did this phenomenon occur? (you can select more then 1) a. natural selection b . mechanical isolation c. prezygotic barriers to reproduction d. high genetic variation in the species

The correct answers would be natural selection and high genetic variation in the species.

Natural selection refers to the natural phenomenon by which organisms which are better adapted or have survival traits tend to survive and reproduce more in the environment.

It leads to an increase in the frequency of the trait in a population.

Genetic variation refers to the sum total of all the genetic characteristics present in a population. Higher genetic diversity higher are the chances of a population to survive.  

Similarly, different sizes of the beaks are the result of high genetic diversity out of which large size beak was favored by natural selection.  

Ultimately, the large beak size trait spreads through the population.

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