(Click on the image to view the phylogenetic tree.)

The phylogenetic tree above is based off of 1.35 kb of mtDNA sequence from fossils of Canadian geese (highlighted), Hawaiian geese, and other members of the genus Branta. The Canadian geese diverged dramatically and were found to be paraphyletic. In order to test the DNA sequences, researchers radiocarbon-dated collagen from the bones of the geese. They found that the Branta split from the genus Anser approximately 4.5 million years ago. The Canadian geese are placed where they are because the B. sandvicensis subspecies and the Giant Hawaii Goose are larger than B. canadensis. Also, the  B. leucopsis, B. bernicla subspecies and B. ruficollis are smaller than the Canadian geese subspecies.
For more information about this phylogenetic tree and how researchers obtained this information, please visit this website.

 
(Click on the image to see the subspecies phylogenetic tree.)

Under the species Branta canadensis there are eleven subspecies that differ in size, body proportion, where they reside, and how well they are able to fly. The tree above shows how the subspecies are different based on where they reproduce and to where they migrate. Under the characteristics of subspecies column, the first place mentioned is where the subspecies reproduces and the second place is where they migrate to for winter. This is the main way to differentiate between the different subspecies.

Interested in learning about the habitat of Canadian geese? Click here.
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