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THE TREE ROOM

Primer on trees

Tree misinterpretations

Field guide to evolutionary trees

How to build a tree

Trees matter

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For museums and zoos

Credits

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The Tree Room : Trees matter :

Evolutionary matchmaking

A similar phylogenetic approach can help us conserve highly endangered species. For example, when biologists went looking for a mate for Lonesome George, the last surviving Galapagos tortoise of his species from the island of Pinta, they turned to phylogenetics. The researchers built a tree based on the DNA of tortoises from many different islands to find Lonesome George's closest relatives.4 Unfortunately, Lonesome George remained lonesome: no tortoises were closely enough related to produce viable offspring, and George died in 2012. However, other efforts to apply phylogenetics in this field have had happier endings. Biologists recently investigated the evolutionary history of the Floreana Galapagos tortoises, which were thought to have been driven extinct more than 150 years ago through overharvesting by sailors. The research team analyzed DNA samples from museum specimens of the Floreana tortoises and used those, along with the DNA sequences of living tortoises from many islands, to build a phylogenetic tree.5 To their surprise, the Floreana sequences formed a tight knit clade with some living tortoises from the island of Isabela. It seems that in the 1800s, sailors transported some native Floreana tortoises to Isabela and left them there — where their descendents still live today! Now, these survivors are the focus of a mission aimed at reviving the long lost species.

tortoise tree
Phylogenetics revealed that the Floreana Galapagos tortoises were not actually extinct, but that their genes survived on the island of Isabela.

4 Burns, C.E., C. Ciofi, L.B. Beheregaray, T.H. Fritts, J.P. Gibbs, C. Marquez, C., … and A. Caccone. 2003. The origin of captive Galapagos tortoises based on DNA analysis: Implication for the management of natural populations. Animal Conservation 6:329-337.

5 Poulakakis, N., S. Glaberman, M. Russello, L.B. Beheregarya, C. Ciofi, J.R. Powell, and A. Caccone. 2008. Historical DNA analysis reveals living descendants of an extinct species of Galapagos tortoise. Proceedings of the National Academy of Sciences USA 105:15464-15469.

Tortoise tree adapted from Poulakakis, N., S. Glaberman, M. Russello, L.B. Beheregarya, C. Ciofi, J.R. Powell, and A. Caccone. 2008. Historical DNA analysis reveals living descendants of an extinct species of Galapagos tortoise. Proceedings of the National Academy of Sciences USA 105:15464-15469.

Trees matter
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Evo examples
Feeling lost? Review tree basics with the primer.