Answer:
Phylogenetic trees can be described as diagrams which represents the evolutionary histories of organisms. The organisms that share more common traits or functions are more closer to one another in the diagram.
The phylogenetic tree in the above diagram shows that the ancestors of Danes, Chinese and Tibetans carried the regular EPAS1 alleles.
According to the tree, the Chinese are more closer to the Tibetans as they carry the Tibetan EPAS1 alleles which the Danes do not carry.
The discovery of hydrothermal vents changed all that. Vast communities of animals grew big and fast in the depths! Instead of using light to create organic material to live and grow (photosynthesis), microorganisms at the bottom of the food chain at vents used chemicals such as hydrogen sulfide (chemosynthesis).
Chlorophyll captures light energy from the sun to produce glucose