Genetic study of silkworm helps unravel its long history of domestication

July 3, 2018 by Bob Yirka, Phys.org report

A team of researchers affiliated with several institutions in China has conducted a genetic study of the silkworm in hopes of better understanding its long historical ties to humans. In their paper published in the journal Nature Ecology & Evolution, the group describes their study and what they found.

There are many varieties of silkworms, but only one makes silk that is mass-producible: Bombyx mori. Because of that unique characteristic, B. mori has a very long history of domestication by humans. Most scientists in the field suggest that the relationship began approximately 5000 years ago, and that it likely started in China. In this new effort, the researchers sought to trace the origins of the silkworm to its first domestication to learn more about its history over the past several thousand years.

The genetic study consisted of collecting silkworm samples representing 137 strains. Those samples included strains that were locally bred and even some representing recently improved strains. The team also collected samples of strains that have not been domesticated. They then sequenced the DNA of all the samples and compared them to one another. The group was able to use the DNA data to construct geographic maps that showed the history of the silkworm as it spread between geographic areas.

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Massive genetic study of humpback whales to inform conservation assessments

Study confirms need to protect unique humpback whales in Arabian Sea

Date: January 9, 2017

Source: Wildlife Conservation Society

Scientists have published one of the largest genetic studies ever conducted on the humpback whale (Megaptera novaeangliae) for the purpose of clarifying management decisions in the Southern Hemisphere and supporting calls to protect unique and threatened populations, according to WCS (Wildlife Conservation Society), the American Museum of Natural History, Columbia University, and other organizations.

Using data generated from more than 3,000 skin samples from individual whales ranging from the South Atlantic to the Indian Oceans, the research team has uncovered previously unknown degrees of relatedness between different whale populations. The study will also help inform ongoing conservation reassessments of humpback whale populations, and reaffirms the highly distinct nature of a small, non-migratory population of humpback whales living in the Arabian Sea in need on continued protection.

The study titled "Multiple processes drive genetic structure of humpback whale (Megaptera novaeangliae) populations across spatial scales" appears in the the journal Molecular Ecology.

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Genetic study reveals vulnerability of northwest dolphins

Date:

July 2, 2014

Source:

PLOS

Summary:

A new study estimating population genetic structure of little-known dolphins inhabiting Western Australia's north coast highlights vulnerability.

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Distinct Humpback Whale Populations Found in North Pacific

Five distinct humpback whale populations have been identified across the North Pacific Ocean in the most comprehensive genetic study of the mammals in this region yet, a new study reports.

The ranges of the newly identified populations include: Hawaii; Mexico; Central America; Okinawa and the Philippines; and an additional West Pacific population whose range has yet to be determined more specifically.

Humpback whales are found in all oceans of the world, but the North Pacific humpbacks are genetically isolated enough to be considered a subspecies of other humpbacks, of which the new populations are further subclassifications, study co-author Scott Baker, a professor of fisheries and wildlife at Oregon State University, said in a statement. 

Continued

Genetic Study Pursues Elusive Goal: How Many Humpbacks Existed Before Whaling?

Feb. 13, 2013 — Scientists from Stanford University, the Wildlife Conservation Society, the American Museum of Natural History, and other organizations are closing in on the answer to an important conservation question: how many humpback whales once existed in the North Atlantic?

Photo: Salvatore Cerchio/Wildlife Conservation Society.

Building on previous genetic analyses to estimate the pre-whaling population of North Atlantic humpback whales, the research team has found that humpbacks used to exist in numbers of more than 100,000 individuals. The new, more accurate estimate is lower than previously calculated but still two to three times higher than pre-whaling estimates based on catch data from whaling records.

Known for its distinctively long pectoral fins, acrobatics, and haunting songs, the humpback whale occurs in all the world's oceans. Current estimates for humpback whale numbers are widely debated, but some have called for the level of their international protection to be dropped.

Continued: http://www.sciencedaily.com/releases/2013/02/130213152416.htm

Ancient Warming May Have Reunited Polar and Brown Bears, for a Bit

Polar bears' past may echo their future, indicates a genetic study that finds the white-furred, sea ice-dwelling bears interbred with brown bears long after the two species separated as much as 5 million years ago.

Climate change likely drove this mixing among bears, writes the research team, noting there is evidence this is happening again.   

"Maybe we're seeing a hint that in really warm times, polar bears changed their lifestyle and came into contact, and indeed interbred, with brown bears," said study researcher Stephan Schuster, a professor of biochemistry and molecular biology at Pennsylvania State University, and a research scientist at Nanyang Technological University in Singapore, in a statement.

Continued:  http://www.livescience.com/21775-polar-bear-evolution-climate.html

Genetic study of cave millipedes reveals isolated populations and ancient divergence between species

Last week the International Journal of Myriapodology published the first population genetic study of cave millipedes. This research highlights an important challenge in the conservation of cave biodiversity – that for many species caves are 'islands' of habitat that support isolated and genetically distinct populations.

The southern Cumberland Plateau in Tennessee and Alabama, USA is known for its high cave density. In addition, it has the highest cave biodiversity of any region in North America. Millipedes of the genus Tetracion range across this biodiversity hotspot. These millipedes, which can grow up to 8 cm in length, are common scavengers in cave communities. Like many cave animals, Tetracion millipedes have reduced pigmentation and non-functional eyes.

The authors used genetic techniques to compare Tetracion populations and species. They found that Tetracion populations were generally isolated from one another. In addition, divergence between Tetracion species was high, suggesting that members of the genus diverged several million years ago.

Original source: Loria, S.F., K.S. Zigler and J.J. Lewis. 2011. Molecular phylogeography of the troglobiotic millipede Tetracion Hoffman, 1956 (Diplopoda: Callipodida: Abacionidae). International Journal of Myriapodology 5:35-48. doi: 10.3897/ijm.5.1891

http://www.eurekalert.org/pub_releases/2011-10/pp-gso101711.php