Conclusion: Most molecular data support the phylogeny in part a.

423.25 Two possible phylogenies of the human, chimpanzee, and gorilla relationships. One phylogeny suggests (a) that humans and chimpanzees have the more recent ancestor. The other phylogeny suggests (b) that humans split from the group first and that chimpanzees and gorillas have the more recent ancestor.


Ancestral organism




Xenopus laevis (frog) Corn

Saccharomyces (yeast) Oxytricha nova Dictyostelium (Slime mold) Trypanosoma brucei

Escherichia coli Pseudomonas testosteroni Agrobacterium tumifaciens Corn mitochondria Bacillus subtilis Anacystis nidulans Corn chloroplast Flavobacterium heparinum

Halobacterium volcanii Methanospirillum hungatei Methanobacterium formicicum Methanococcus vannielii Thermoproteus tenax Sulfolobus solfataricus

423.26 A universal tree of life can be constructed from 16S rRNA sequences. Note that sequences from corn mitochondria and chloroplasts are most similar to sequences from eubacteria, confirming the endosymbiotic hypothesis that these eukaryotic organelles evolved from bacteria (see Chapter 20).

revealed that there are three divisions of life: the eubacteria (the common bacteria), the archaea (a distinct group of lesser-known prokaryotes), and the eukaryotes. __

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