Ancient DNA reveals evolution of giant bears in the Americas

Date: April 20, 2016

Source: University of Adelaide

The work of University of Adelaide researchers is shedding new light on the evolution of what are believed to be the largest bears that ever walked the Earth.

Dr Kieren Mitchell, from the University's Australian Centre for Ancient DNA, School of Biological Sciences, has a new paper just published in Biology Letters.

He writes: "During the Pleistocene (2.5 million years ago -- 11 thousand years ago) giant bears weighing over 1,000kg roamed both North and South America. These giants belonged to a now practically extinct subfamily of bears -- Tremarctinae -- which is today only represented by the small, herbivorous Andean spectacled bear (Tremarctos ornatus).

"The giant North American bears (Arctodus) and South American bears (Arctotherium) have long been believed to be each others' closest relative. However, by comparing ancient DNA data obtained from representatives of the two extinct genera and comparing them with the living species, we were able to show that Arctotherium is most closely related to Tremarctos and not Arctodus.

Continued ...

Bowhead Whales: Ancient DNA Sheds Light On Arctic Whale Mysteries

ScienceDaily (Oct. 19, 2012) — Scientists from the Wildlife Conservation Society, the American Museum of Natural History, City University of New York, and other organizations have published the first range-wide genetic analysis of the bowhead whale using hundreds of samples from both modern populations and archaeological sites used by indigenous Arctic hunters thousands of years ago.

In addition to using DNA samples collected from whales over the past 20 years, the team collected genetic samples from ancient specimens -- extracted from old vessels, toys, and housing material made from baleen -- preserved in pre-European settlements in the Canadian Arctic. The study attempts to shed light on the impacts of sea ice and commercial whaling on this threatened but now recovering species. The study appears in the most recent edition of Ecology and Evolution.

"Our study represents the first genetic analysis of bowheads across their entire range," said Elizabeth Alter, the study's lead author and now a professor at City University of New York. 

"The study also illustrates the value of ancient DNA in answering questions about the impact of changing climate and human exploitation on genetic diversity in bowhead whales."

Read on:  http://www.sciencedaily.com/releases/2012/10/121019130502.htm