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17 December 2014

Deforestation threatens species richness in streams ...

05 December 2014

Unsichtbare Arten - Bedrohte Arten sind in Verbreitungsmodellen unterrepräsentiert...

02 December 2014

Von der Forschung in die Praxis: „Algenmelder“ für Gewässer...

12 November 2014

On a safari through the genome – genes offer new insights into the distribution of giraffes...

31 October 2014

Frankfurter Biodiversität und Klima Forschungszentrum (BiK-F) erhält Spitzenbewertung vom Wissenschaftsrat ...

23 October 2014

Vortrag „Long term dynamics in the Serengeti Ecosystem: Lessons for Conservation and Society “ ...

25 September 2014

Dengue fever and malaria in the Himalayas...

18 September 2014

Vorratshaltung beim Tannenhäher: Samenverstecke nutzen dem "gefiederten Förster" mehr als den Bäumen...

15 September 2014

The Biodiversity and Climate Research Centre opens its doors to the public...

11 September 2014

Pesticides are more toxic for soil organisms in dry soil and at enhanced temperatures ...

01 September 2014

Vortrag 4. September „The Climate Change Challenge and Opportunities“ ...

01 August 2014

More People Means More Plant Growth, NASA Data Show ...

25 July 2014

Erstmals Sandmücke in Hessen entdeckt...

09 July 2014

Climate change: Tropical species are most vulnerable to rising temperatures...

25 June 2014

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18 June 2014

Spanish slug – busting an invasion myth...

17 June 2014

The hidden history of rain: plant waxes reveal rainfall changes during the last 24,000 years...

11 June 2014

It’s complicated - new insights into the evolutionary history of bears ...

12 May 2014

A tale of survival – scientists reveals how fish were able to colonise poisonous springs...

08 May 2014

New ways for understanding the link between the uplift of the Tibetan Plateau and species diversity...

29 April 2014

Gehen oder bleiben? – Neue Emmy Noether-Gruppe erforscht die Klima-Anpassung von Vögeln ...

08 April 2014

Mapping ecosystem services: New method shows seed dispersal pathways of hornbills...

26 March 2014

Study yields 'Genghis Khan' of brown bears, and brown and polar bear evolution...

18 March 2014

Ants plant tomorrow's rainforest...

04 March 2014

Allergikern blüht etwas: Erhöhte Fitness der Beifußambrosie in Europa nachgewiesen ...

12 February 2014

Zukunftsthema Infektionskrankheiten – zwei neue Forschungsprojekte im Bereich Medizinische Biodiversität und Parasitologie...

05 February 2014

Aquatic Insects – a tremendous potential for research on diversification...

05 February 2014

Coffee: More biodiversity, better harvest ...

20 January 2014

Erfolgreiche Renaturierung von Gewässern: Das biologische Umfeld ist entscheidend...

Press Releases

It’s complicated - new insights into the evolutionary history of bears

Frankfurt am Main, Germany, June 11th, 2014. According to researchers of the LOEWE Biodiversity and Climate Research Centre (BiK-F), Goethe University Frankfurt and the U.S. Wildlife Service, several bear species that today only occur in America or in Asia have hybridized during their evolutionary history. The Beringia land bridge, which connected the habitats of these species in former times, might have enabled their encounter. The large-scale study is based on the comparison and analysis of genetic material from all extant bear species. The results have been published recently in the journal Molecular Biology and Evolution.

Whether in documentaries or in the zoo - everyone has seen and knows about brown bears, polar bears and giant pandas. However, there are several other bear species in Asia and South America that are less well-known, such as the sloth bear, the Asian black bear or the spectacled bear. There are eight bear species that still exist worldwide. Despite many years of research, the exact relationships between them remain unresolved.

Who with whom? Polar bear and brown bear have hybridized

Previous analyses of genetic material of polar bears and brown bears have proven already that the two species have hybridized during their long evolutionary history. This behavior can still be observed today and the ongoing climate change drives the bears even closer. It is therefore likely that there have been similar exchanges of genetic material between other species of the bear family.

... as well as brown bears and black bears 

To shed light on this, a team of the German Biodiversity and Climate Research Centre (BiK-F) and the Goethe University Frankfurt in cooperation with colleagues from the US have now analyzed certain genome parts of all bear species alive today. "We were able to show that several bear species have hybridized during their evolutionary history. The exchange can still be traced in the genetic makeup of today's bears," says the lead author of the study, Verena Kutschera (BiK-F). This mix-up makes it difficult to classify some gene fragments as belonging to a particular species.

Beringia land bridge serving as an intercontinental meeting point 

Surprisingly, several bear species which nowadays live on different continents have also taken part in the mating and thus gene exchange. This may have been possible because the significantly lower sea level during past ice ages resulted in a land bridge between Asia and North America, the Beringia land bridge. Thus the ancestors of today’s bear species, e.g. of the Asian black bear and the American black bear, had the opportunity to meet and to mate.

Darwin’s species tree is insufficient to map complicated relationships

All eight bear species that occur today are well adapted to their present habitat and differ physically very much. A prime example for this are polar bears and black bears. Nevertheless, the speciation has not finished yet at some individual genes, which additionally complicates the research of the evolution of bears.

With new molecular methods more genes might be discovered in the genomes of mammal species that could originate from other species. Apparently separate genetic lineages turn out to have merged – sometimes repeatedly – during the evolutionary history and exchanged genetic material with each other. "The traditional pedigree introduced by Darwin is not always suitable to map evolutionary history in full detail. So-called phylogenetic networks a more useful to depict the genetic mix-up that we have found ", comments evolutionary biologist Prof. Dr. Axel Janke, BiK-F, leader of the research team. The study demonstrates that evolution often is not a linear process; thanks to modern molecular methods its complex processes can finally be revealed.

Publication:
Kutschera, V. et al. Bears in a forest of gene trees: Phylogenetic inference is complicated by incomplete lineage sortign and gene flow – Molecular Biology and Evolution, DOI: 10.1093/molbev/msu186

Press images:

 Schwarzbaer TBidon
American black bear. Copyright: Tobias Bidon [Download in 300 dpi] http://tinyurl.com/kwjj4z2

Baeren Verwandschaft

Phylogenetic network showing the relationship of all extant bear species. Copyright: BiK-F [Download in 300 dpi] http://tinyurl.com/oevupnv

Terms of use:  Images may be used for editorial purposes only. Please state the copyright information as given in the image caption. Use of images for commercial purposes prohibited..

For further information please contact:

Prof. Dr. Axel Janke
LOEWE Biodiversity and Climate Research Centre (BiK-F)
Tel. +49 (0)69 7542 1842
axel.janke@senckenberg.de

or

Verena Kutschera
LOEWE Biodiversity and Climate Research Centre (BiK-F)
Tel. +49 (0)69 7542 1828
verena.kutschera@senckenberg.de

or

Sabine Wendler
LOEWE Biodiversity and Climate Research Centre (BiK-F)
Press officer
Tel. +49 (0)69 7542 1838
Sabine.wendler@senckenberg.de

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