which of the following sets of data provides evidence that best supports common ancestry for organisms in all three domains?
Answer:
There are several lines of evidence that support the theory of common ancestry of organisms in all three domains. Here are some of the key pieces of evidence:
1. Homologous Structures:
One of the most compelling pieces of evidence for common ancestry is the existence of homologous structures in different species. Homologous structures are anatomical features, such as limbs or wings, that are similar in different organisms because they are inherited from a common ancestor. For example, the forelimbs of mammals, the wings of birds, and the flippers of whales and dolphins all have the same basic structure, despite the fact that they are adapted for different purposes. This suggests that they all evolved from a common ancestor with forelimbs.
2. Molecular Biology:
Comparison of DNA and RNA sequences can provide evidence of common ancestry. All living organisms use the same basic genetic code, which consists of the same four nucleotide bases (adenine, guanine, cytosine, and thymine in DNA, or adenine, guanine, cytosine, and uracil in RNA). The fact that this code is identical in all living organisms is strong evidence that they all share a common ancestor. In addition, comparison of specific genes and their sequences can reveal similarities among different species that indicate common ancestry.
3. Fossil Record:
The fossil record provides evidence of the evolution of species over time and supports the idea of common ancestry. Fossils of transitional forms, such as those of early reptiles with bird-like features, provide a clear picture of how species can evolve gradually over time. The existence of fossils that show intermediate stages between major groups of organisms is a strong indication that they all share a common ancestry.
4. Biogeography:
Biogeography, the study of the distribution of living organisms, provides evidence of common ancestry. Species that are geographically close together are often more closely related than those that are far apart. This suggests that the ancestors of these species were once geographically close and diverged into different species over time. For example, the marsupial mammals of Australia are all descended from a common ancestor that colonized that continent millions of years ago.
In summary, all of these lines of evidence provide strong support for the idea of common ancestry for organisms in all three domains.