What Is Phenotype?
Genes are, essentially, the blueprint of the way something looks, grows, behaves, and interacts with it’s surroundings – among other things. Genes can differ from other genes that do the same thing (eye color, for example) due to the way the nucleotides are arranged in the gene. These differences are called alleles. Where they’re located on the chromosome that contains that allele is called the locus. And because chromosomes occur in pairs, each organism have two alleles – one on each locus on each chromosome.
When these two alleles “match” (ie: two blue eye genes) they’re called homozygous – homo meaning same in Greek. When the alleles are different (ie: one brown and one blue eye gene) they’re called heterozygous – hetero meaning different in Greek. In a situation where the alleles are heterozygous, the dominant gene will be displayed whereas the recessive gene is suppressed. In the case of incomplete dominance, both genes will be expressed to some degree determined on a separate allele.
There are two camps genes largely fall into: phenotype (the result of the genes you can see – either dominant or homozygous) and genotype (the genes that influence the result of the phenotype.) Phenotypes are the genetics you can see – male versus female, red versus blue, big versus small, etc. Phenotypes are influenced by both the genotype as well as the environment and can change with age, care, stress, or other factors outside of genetics, whereas genotypes cannot be changed or influenced once encoded.
Examples of Phenotype
Flamingos are a good example of a phenotype in action – they’re naturally white but turn bright pink because they eat algae, brine shrimp, and other crustaceans – which have high level of carotenoids that turn them pink. The intensity of their coloration depends heavily on how much they eat and how healthy their food is.
Other than flamingos, phenotype examples are easy to come by – look at any animal and any characteristic you see is a phenotype. Even their behavior, intelligence, and personality are phenotypes.
Phenotypes can – but are not always – influenced by things like diet, stress, environment, care, or any other outside factor. But they are always influenced by their genotype (without the ability to convert and store the carotenoids the flamingos eat, they wouldn’t turn pink.)