Final answer:
To determine species relatedness, genetic similarities and homologous structures are compared, which reflect common ancestry. Phylogenetic trees visually represent these evolutionary relationships, and genetic analysis would show species with a closer common ancestor have more genetic similarities.
Step-by-step explanation:
Understanding Species Relatedness
To best determine how closely species are related to each other, scientists compare genetic similarities and physical characteristics. Homologous structures are an important indicator of common ancestry, which include similar morphological (structures and form) and genetic patterns. For example, similarities in the arrangement of bones in a bat's wing and a human's arm point to a common ancestor. Phylogenetic trees serve as a visual representation of these relationships, illustrating how species descend from common ancestors.
When analyzing species A, B, D, and E, one would expect that species D and E share more genetic similarities with each other than with species A and B, reflecting closer evolutionary relatedness. The same applies inversely between species A and B.
These genetic investigations are similar to detective work where scientists collect data to make evolutionary connections, utilizing tools such as generalized linear mixed-effects models and phylogenetically independent contrasts to account for the hierarchical nature of species relationships.