Although young children are constantly told how much they look like their mothers and fathers, it would be very strange if a child were born looking exactly like his/her mother or father. This is because humans are heterozygous, which essentially means that each combination of a mother’s eggs and a father’s sperm will produce a different variation of a human being. As a result, if some more advanced species wanted to artificially select humans to appear unilaterally the same as, say, the president, they would be unable. The only way to produce human masses in the president’s image would be to repeatedly clone the president. These same ideas can be applied to the reproductive strategies of the apple tree.
Apples are, in fact, considered extremely heterozygous, meaning that the variation within a single apple tree’s potential offspring is huge. Evolutionarily, this extreme heterozygous quality has been deeply advantageous for the apple tree. Because there unique definition of what it means to be an apple tree contained within every seed—or, five vastly different potential offspring per apple—it’s more likely that one or many of an apple tree’s offspring will be able to thrive in the specific environmental niche into which the tree’s seeds are distributed. This quality has allowed the apple tree to thrive in many distinct environments throughout the globe, including New Zealand, central Asia, and the east and west coasts of the United States.
From a human perspective (as opposed to an evolutionary one) the fact that apple’s are heterozygous is not quite as fantastic. Studies such as the one conducted by Brianna L. Gross and her colleagues have suggested that domestication of apples over the course of the past eight centuries has had little or no impact on extent of the apple tree’s heterozygous quality. Consequently, if a farmer happens upon an apple tree in the woods with delicious tasting apples and thinks he/she is going to make a fortune by using that tree’s many seeds to plant an orchard, they are unfortunately incorrect. The orchard that the farmer produces might not even contain a single good-tasting apple.
As explored in greater depth elsewhere on this blog, farmers and scientists have of course discovered a solution to this problem—if they hadn’t, people wouldn’t be able to go into a super-market and grab a golden delicious apple to have with their lunch. The technique that has been developed is called grafting. For more information on the subject, continue learning by exploring the rest of this blog!