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Why Study the Tree of Life?

 

Why Study the Tree of Life?

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HIV-AIDS virus

By providing a chronicle of past evolutionary events, phylogenetic trees have become central to understanding the process of evolution, and therefore to the interpretation of all biological information.

 

The Tree of Life is of great scientific interest, but does it have immediate practical value? The answer is a definite “Yes”!

 

Phylogenetic comparisons with “model organisms” (such as the chimpanzee, mouse, zebra fish and yeast) are providing major insights into the structure and function of the human genome, knowledge that will enable us to address a wide variety of human disorders.

Medical journals routinely publish phylogenetic trees, which have proven to be critical in identifying and tracing the origins of emerging infectious diseases such as HIV, the Ebola and West Nile viruses, anthrax, and influenza.

 

 

HIV

In the case of HIV (the virus responsible for AIDS, now the leading infectious cause of death worldwide), phylogenetic studies have revealed multiple sources of the disease in nonhuman primates and have also helped trace its transmission through human populations.

 

HIV tree

 

 

Rabies

Rabies

 

Rabies, which is transmitted through blood and saliva, is the tenth leading cause of human death from infectious disease. As it spreads from host to host the viral strain accumulates mutations in its genetic material, and from these we can recover its phylogenetic history.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The map below shows a phylogeny of a rabies virus strain that spread across Europe starting in the 1930s. This strain originated in African dogs, but then jumped host species — into the red fox in southern Europe and later into the raccoon dog in north eastern Europe. The tree shows a characteristic “transmission wave” as the virus spread westward across Europe starting in the 1950s.

 

Rabies map

 

 

 

Teosinte

Agriculture

Knowledge of phylogenetic relationships also plays a key role in agriculture, especially by identifying the wild relatives of domesticated plants and animals (potatoes from South America, chickens from southeast Asia, wheat from the Middle East), guiding genetic improvements (engineering resistance to drought and pathogens) and locating potential biological control agents.

 

For example, the discovery that the Mexican grass teosinte is the wild ancestor of cultivated maize has led to an understanding of the genes that could enhance desirable key attributes of the cultivated plant.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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