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Doubts about complex speciation between humans and chimpanzees
Daven C Presgraves1, Soojin V Yi
1Department of Biology, University of Rochester, Rochester, NY 14627, USA. dvnp@mail.rochester.edu
Trends in Ecology & Evolution
|August 12, 2009
Summary
Human and chimpanzee speciation may be simpler than previously thought. New analysis suggests neutral evolution and male-biased mutation, not complex hybridization, explain DNA divergence patterns observed between species.
Area of Science:
- Evolutionary biology
- Genomics
- Molecular evolution
Background:
- Large-scale DNA data suggest complex speciation between humans and chimpanzees, involving hybridization and selection.
- Observed patterns include variable autosomal divergence and lower X chromosome divergence between humans and chimpanzees.
Purpose of the Study:
- To explain the observed DNA divergence patterns using a simple speciation model.
- To challenge the complex speciation hypothesis for human-chimpanzee divergence.
Main Methods:
- Analysis of large-scale DNA sequence data from humans and chimpanzees.
- Application of neutral molecular evolution principles.
- Investigation of factors influencing X chromosome divergence, such as mating systems and male-biased mutation.
Main Results:
- The wide range of autosomal divergence is explained by stochastic variation in coalescence times.
- Lower human-chimpanzee X chromosome divergence is consistent with differences in male-biased mutation rates due to mating systems.
- Two additional divergence patterns were identified that contradict the complex speciation model.
Conclusions:
- Simple speciation coupled with neutral molecular evolution adequately explains key patterns of human-chimpanzee DNA divergence.
- The complex speciation model, involving hybridization and strong selection, is questioned.
- The findings suggest a re-evaluation of the speciation process between humans and chimpanzees is warranted.
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