In a certain species of pine trees, the short needles are dominant to long needles. when discussing the pine tree needles as being short or long we are referring to the

We are referring to the phenotype of the species.

The phenotype describes the set of observable characteristics of an species. It depends on the expression of genes (genotype) and the environment. For example, humans having type 2 diabetes can be linked to both genetic predispositions and poor eating habits.

Epigenetic modifications can also modify a phenotype. Epigenetics is a process that explains how environmental factors (diet, smoking, stress ...) influence the expression of genes and therefore the phenotype.