Using a new method for assessing the genetic ancestry of tigers, researchers discovered that many apparently "generic" tigers actually represent purebred subspecies and harbor genomic diversity no longer found in nature.
" Assessment of ‘verified subspecies ancestry’ (VSA) offers a powerful tool that, if applied to tigers of uncertain background, may considerably increase the number of purebred tigers suitable for conservation management," said Shu-Jin Luo, of the National Cancer Institute, Frederick. “This approach would be of particular importance to tiger subspecies that have suffered severe population decline in the wild and/or lack of efficient captive breeding.”
For instance, he said, the Indochinese tiger has been classified as a different subspecies from the Malayan tiger, leaving just 14 recognized Indochinese individuals in captivity. “Thus,” Luo added, “verification of VSA Indochinese tigers, establishment of captive breeding programs, and preservation of remaining Indochinese tiger populations in the wild should be set as one of the top priorities in the global tiger conservation strategy.”
Tigers in general are disappearing rapidly from the wild, from over 100,000 in the 1900s to as few as 3,000 last year, said the researchers, led by Stephen O'Brien also of the National Cancer Institute, Frederick. By contrast, captive tigers are flourishing, with 15,000–20,000 individuals worldwide, outnumbering their wild relatives between five and seven to one.
A relatively small portion of the world's captive tigers—some 1,000 individuals in all—are managed through coordinated breeding programs that aim to preserve genetic variability representative of geographic and subspecies groupings found in the wild, the researchers said. The rest are of hybrid or unknown origin and are kept in zoos, farms, breeding facilities, circuses, and private homes. Scientists have long debated the role that captive tigers might play in conservation efforts.
To address the issue in the new study, the researchers developed a strategy for assessing the subspecies affiliation of tigers on the basis of diagnostic genetic markers obtained from 134 "voucher" tigers. They applied the method to samples from 105 captive tigers from 14 countries collected over 20 years. Of those, 49 individuals were found to represent one of five purebred subspecies, or VSA. The rest of the cats had mixed backgrounds.
They suspect that the proportion of purebreds observed in their study will be an overestimate for captive tigers worldwide. Nevertheless, they said, "If 14–23 percent of the over 15,000 existing captive tigers would prove to be VSA, the number of tigers with pure subspecies heritage available for conservation consideration would considerably increase.
" Also, an important fraction of captive tigers retain genetic diversity unreported, and perhaps absent, in the wild populations. A wide-ranging identification of captive VSA tigers to assess their potential for inclusion into comprehensive, integrated in situ and ex situ management plans could significantly increase population sizes and help maintain genetic variability and population viability of this iconoclastic species."
The researchers include Shu-Jin Luo, National Cancer Institute, Frederick, MD, Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MI; Warren E. Johnson, National Cancer Institute, Frederick, MD; Janice Martenson, National Cancer Institute, Frederick, MD; Agostinho Antunes, National Cancer Institute, Frederick, MD, CIMAR, Universidade do Porto, Porto, Portugal; Paolo Martelli, Veterinary Department, Ocean Park, Aberdeen, Hong Kong; Olga Uphyrkina, Institute of Biology and Soil Sciences, Vladivostok, Russia; Kathy Traylor-Holzer, Conservation Breeding Specialist Group/SSC/IUCN, Apple Valley, MI; James L.D. Smith, Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MI; and Stephen J. O’Brien, National Cancer Institute, Frederick, MD
Cathleen Genova | EurekAlert!
Bioinvasion on the rise
15.02.2017 | Universität Konstanz
Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News