What should biologists do when two similar organisms that were originally thought to be separate species are found to interbreed freely and produce normal offspring whenever they live in the same habitat?
Two butterflies have identical wing patterns, but in one the pigment is blue and in the other the pigment is yellow. The original ancestor had green wing pigments. The wing pigment is an example of a(n) .
Suppose a population of a new plant is found on an island. DNA sequencing determines that this plant shares a limited number of genes with plants on the mainland. Within the species, there is great genetic variability. This would suggest that