During a drought on the galapagos islands, finches with larger beaks were able to crack the large tough seeds produced by plants that survived the dry conditions. this is an example of

It is an example of directional selection.

The different kinds of natural selection can influence the distribution of phenotypes within a population. In stabilizing selection, an average phenotype is preferred.

In directional selection, a modification in the surrounding changes the spectrum of the observed phenotypes, and in diversifying selection the extreme values for a trait are preferred over the transitional values. This kind of selection usually pushes speciation.

The directional selection, in the field of population genetics, refers to a mode of natural selection in which an extreme phenotype is preferred over other phenotypes, making the allele frequency to change with time in the orientation of that phenotype.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.