Comparative serological tests demonstrate that the blood serum proteins of the South American llama () exhibit a very high degree of immunological cross-reactivity with anti-serum raised against the Old World camel (). Which of the following statements best explains this biochemical and biogeographical observation?
- Llamas and Old World camels shared a relatively recent common ancestor before ancestral populations were geographically isolated by vicariance.Answer
- BLlamas independently developed serum proteins identical to Old World camels as an acquired physiological response to arid high-altitude environments.
- CThe structural similarity in serum proteins represents an analogous feature resulting from convergent evolution rather than common ancestry.
- DThe precipitation reaction observed in serological tests demonstrates discontinuous genetic variation within a single generation.
Answer
Llamas and Old World camels shared a relatively recent common ancestor before ancestral populations were geographically isolated by vicariance.
High serological cross-reactivity indicates close similarity in blood protein sequences, which directly reflects a shared genetic code derived from a recent common ancestor. Combined with biogeographical evidence, this confirms that ancestral camelids inhabited connected landmasses before geographic isolation led to speciation into modern llamas and camels.
Step-by-Step Solution
Key Concept
Biochemical Homology and Biogeographical Vicariance