Evolutionary relationships refer to the connections between different species based on their shared ancestry. Scientists study these relationships to understand how species have evolved over time, often using tools like phylogenetic trees to illustrate these connections. By examining genetic, morphological, and behavioral traits, researchers can determine how closely related various organisms are. These relationships help explain the diversity of life on Earth and how species adapt to their environments. For example, Darwin's finches on the Galápagos Islands showcase how different species can evolve from a common ancestor to fill various ecological niches. Understanding these relationships is crucial for fields like conservation biology and medicine.