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Direct evidence for the Homo-Pan clade.
Rainer Wimmer1, Stefan Kirsch, Gudrun A Rappold
1Institute of Human Genetics and Anthropology, University of Freiburg, Germany.
Summary
A DNA fragment transposition onto the Y chromosome in a common ancestor provides evidence for a human-chimpanzee (Homo-Pan) clade. This finding supports evolutionary relationships independent of DNA sequence analysis.
Area of Science:
- Genetics
- Evolutionary Biology
- Primatology
Background:
- The evolutionary relationship between humans and African apes, known as the 'trichotomy problem', has been a long-standing debate.
- Previous studies using DNA sequence data have largely supported a Homo-Pan clade (humans and chimpanzees).
Purpose of the Study:
- To investigate the evolutionary relationship between humans and African apes using chromosomal breakpoints as an alternative method.
- To identify shared derived traits supporting specific clades within primates.
Main Methods:
- Comparative mapping of human Y chromosome DNA using fluorescence in-situ hybridization (FISH).
- Analysis of a large DNA contig (approximately 2.8 Mb) on the human Y chromosome.
- Examination of Y chromosomes from great apes, gibbons, and Old World monkeys.
Main Results:
- A transposition of a ~100-kb DNA fragment from chromosome 1 to the Y chromosome was identified in a common ancestor.
- This specific DNA fragment was found exclusively on the Y chromosomes of humans, chimpanzees, and bonobos.
- The fragment was absent in gorillas and other examined primate species.
Conclusions:
- The shared presence of the chromosome-1-derived fragment on the Y chromosome is a synapomorphic trait.
- This genetic marker provides strong, independent evidence for a Homo-Pan clade, corroborating DNA sequence analyses.