Correct Response: D. In taxonomic comparisons, a phenotypic trait, or a trait that exhibits phylogenetic change in a particular group of organisms, is used to determine relatedness. For the trait observed in the beetle to be of taxonomic value, it needs to be present in each generation of beetles, implying that the trait must be heritable. When an observable trait is adaptive (A), it will help the beetle survive a changing environment, but a trait does not need to be adaptive in order for it to have taxonomic value. A trait unique to the beetle species (B) helps in identifying the species, but many shared traits, or combinations of traits, are useful identifying different species A dichotomous key (C) is a tool used to identify an organism's taxonomic, but many heritable traits are not used in creating a key.
