Limited gene flow between two Bengal tiger populations in the western Himalayan foothills

Connectivity could be maintained by relocating villages, and banning sand and boulder mines 

Date: April 26, 2017
Source: PLOS

 
The flow of genes between Bengal tigers in two reserves of the Terai Arc Landscape in western Himalayan foothills is too low, according to a study published April 26, 2017 in the open-access journal PLOS ONE by Surendra Prakash Goyal from Wildlife Institute of India, India, and colleagues.

Tigers are endangered partly due to habitat loss, which can fragment populations and reduce gene flow among them. Gene flow between populations can maintain genetic variation and spread beneficial gene alleles, so understanding the gene flow of isolated tiger populations i.e. in western Himalayan foothills is crucial in developing management strategies for conserving these big cats. Goyal and colleagues analyzed DNA from 71 samples of tissue, blood or scat from Bengal tigers to assess their gene flow in an 1,800-square-kilometer region of the western Himalayan foothills. The region has two main subpopulations of tigers, one in the Rajaji Tiger Reserve and the other in the Corbett Tiger Reserve.

 

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Massive transoceanic gene flow in a freshwater turtle (Testudines: Geoemydidae: Mauremys rivulata) – via Herp Digest

Zoologica Scripta /Article first published online: 3 APR 201

1. Melita Vamberger¹,
2. Heiko Stuckas¹,
3. Dinçer Ayaz²,
4. Petros Lymberakis³,
5. Pavel Široký⁴ and
6. Uwe Fritz^1,*

Author Information

1. ¹Museum of Zoology (Museum für Tierkunde), Senckenberg Dresden, Dresden, Germany
2. ²Faculty of Science, Biology Department, Zoology Section, Ege University, Bornova, Izmir, Turkey
3. ³Natural History Museum of Crete, University of Crete, Irakleio, Crete, Greece
4. ⁴Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic

Email: Melita Vamberger (melita.vamberger@senckenberg.de), Heiko Stuckas (heiko.stuckas@senckenberg.de), Dinçer Ayaz (dincer.ayaz@ege.edu.tr), Petros Lymberakis (lyberis@nhmc.uoc.gr), Pavel Široký (sirokyp@vfu.cz), Uwe Fritz (uwe.fritz@senckenberg.de)

^*Corresponding author: Uwe Fritz, Museum of Zoology (Museum für Tierkunde), Senckenberg Dresden, A. B. Meyer Building, 01109 Dresden, Germany. E-mail: uwe.fritz@senckenberg.de

The freshwater turtle Mauremys rivulata ranges from the Adriatic coast of the Balkan Peninsula through the Aegean region and coastal western and southern Turkey southwards to Israel. In addition, it occurs on several Aegean islands, Crete and Cyprus. Previous investigations using mtDNA sequences found virtually no genetic differentiation across its distribution range, despite some major biogeographical barriers for terrestrial and freshwater biota. Thus, the absence of any phylogeographical differentiation would be unexpected. To re-examine genetic differentiation within M. rivulata, here we use a comprehensive rangewide sampling and information of 13 unlinked polymorphic microsatellite loci and compare these data against mtDNA variation. Our microsatellite analyses reveal a weak population structuring which conflicts, however, with most biogeographical barriers. We conclude that the genetic structure in the vast majority of the species' range has been shaped by massive transoceanic gene flow. This explanation is unlikely for the northernmost populations, which seem rather to be genetically impacted by intentionally released foreign turtles.

DNA study clarifies how Polar bears and brown bears are related

"In retrospect, I think we were wrong about the directionality of the gene flow between polar bears and Irish brown bears," she said.

March 2013. At the end of the last ice age, a population of polar bears was stranded by the receding ice on a few islands in south-eastern Alaska. Male brown bears swam across to the islands from the Alaskan mainland and mated with female polar bears, eventually transforming the polar bear population into brown bears.

Evidence for this surprising scenario emerged from a new genetic study of polar bears and brown bears led by researchers at the University of California, Santa Cruz. The findings, published March 14 in PLOS Genetics, upend prevailing ideas about the evolutionary history of the two species, which are closely related and known to produce fertile hybrids.

Limited hybridisation

Previous studies suggested that past hybridization had resulted in all polar bears having genes that came from brown bears. But the new study indicates that episodes of gene flow between the two species occurred only in isolated populations and did not affect the larger polar bear population, which remains free of brown bear genes.

At the centre of the confusion is a population of brown bears that live on Alaska's Admiralty, Baranof and Chicagof Islands, known as the ABC Islands. These bears--clearly brown bears in appearance and behaviour--have striking genetic similarities to polar bears.

"This population of brown bears stood out as being really weird genetically, and there's been a long controversy about their relationship to polar bears. We can now explain it, and instead of the convoluted history some have proposed, it's a very simple story," said co-author Beth Shapiro, associate professor of ecology and evolutionary biology at UC Santa Cruz.

Shapiro and her colleagues analysed genome-wide DNA sequence data from seven polar bears, an ABC Islands brown bear, a mainland Alaskan brown bear, and a black bear. The study also included genetic data from other bears that was recently published by other researchers. Shapiro's team found that polar bears are a remarkably homogeneous species with no evidence of brown bear ancestry, whereas the ABC Islands brown bears show clear evidence of polar bear ancestry.

Continued: http://www.wildlifeextra.com/go/news/polar-brown-bears.html