Consider two populations of birds: an original population on the mainland and a small population on a volcanic island. what data should you collect to determine if they are two different species according to the biological species concept?
a. the relative fitness of the mainland and island individuals.
b. the range of foods eaten by members of the two populations.
c. the degree of genetic difference between the two populations.
d. the physical appearance of the birds in the two populations.
e. the percentage of viable, fertile hybrid offspring formed if the two populations encounter each other.