Question

The sunflower species Helianthus paradoxus, H. deserticola, and H. anomalus all arose from homoploid hybrid speciation between the same two parental sunflower species, H. annuus and H. petiolaris. Yet, the three hybrid species are adapted to the different environments (salt marshes, desert flats, and sand dunes, respectively) in which they occur. Moreover, the three species differ from each other somewhat in appearance and other traits when grown together in a common environment. Which of the following would NOT be a potential explanation for the differences described here?

a. Each species is derived from different individual H. annuus and H. petiolaris parents, and genetic variation within each parental species could contribute to the differences.

b. Natural selection favored different combinations of H. annuus and H. petiolaris alleles at different genes in F2 and later hybrids living in each environment, leading to genetic differences in the three species.

c. The three hybrid populations are genetically similar, but phenotypic plasticity leads to different phenotypes in each environment.

d. Novel mutations occurring after hybridization in different hybrid populations were favorable to survival and reproduction in their respective environments.

e. All of the above explanations could explain the differences between the three species.

Answer 1

Answer e may be correct.

e. All of the above explanations could explain the differences between the three species.