Introduction to Natural Selection Practice Test

In a bird population, beak depth varies and is heritable, influenced by alleles D (deeper beak) and d (shallower beak). A shift in available seeds occurs: most remaining seeds are large and hard, and birds with shallower beaks crack them less efficiently and produce fewer offspring. Birds with deeper beaks more often obtain enough food to reproduce. The population continues to interbreed in the same region, with minimal immigration. Which outcome is most likely after several generations?

In a bird population, beak depth varies and is heritable. After several years of drought, only hard, large seeds remain abundant. Birds with deeper beaks crack these seeds more efficiently and produce more offspring than birds with shallower beaks. Both beak depths continue to occur among nestlings. Which outcome is most likely over generations?