Final answer:
Closely related organisms share a significant amount of genetic material, which signifies genetic similarity and indicates evolutionary relationships. For instance, humans and chimpanzees share about 98% of their genes, showing a common ancestor. However, molecular and morphological data combined are needed for accurate phylogenetic analysis.
Step-by-step explanation:
Organisms that are more closely related share more DNA segments that code for the same genes that make the organisms genetically similar. This genetic similarity comes from a shared ancestry, with variations occurring due to descent with modification. The DNA of closely related organisms, like family members, has a high level of alignment, making their external and internal characteristics quite similar.
This high degree of similarity in DNA sequences is a crucial indicator of the evolutionary relationships between species. For example, humans and chimpanzees share about 98% of their genes, pointing to a recent common ancestor, and highlighting the strength of genetic evidence in understanding our place within the evolution of life on Earth.
Nevertheless, it's important to recognize that sometimes two segments of DNA code might randomly share a high percentage of bases, causing two species to appear more closely related than they actually are. To address these situations, scientists utilize computer technologies and a combination of morphological and molecular information to more accurately determine the phylogeny of organisms.