A Single Origin for Dogs South of Yangtze River
An interesting paper on the origin of dogs in the forthcoming issue of Molecular Biology and Evolution - mtDNA Data Indicate a Single Origin for Dogs South of Yangtze River, Less Than 16,300 Years Ago, from Numerous Wolves:
There is no generally accepted picture of where, when, and how the domestic dog originated. Previous studies of mitochondrial DNA mtDNA have failed to establish the time and precise place of origin because of lack of phylogenetic resolution in the so far studied control region CR, and inadequate sampling. We therefore analyzed entire mitochondrial genomes for 169 dogs to obtain maximal phylogenetic resolution and the CR for 1,543 dogs across the Old World for a comprehensive picture of geographical diversity.
Hereby, a detailed picture of the origins of the dog can for the first time be suggested. We obtained evidence that the dog has a single origin in time and space and an estimation of the time of origin, number of founders, and approximate region, which also gives potential clues about the human culture involved. The analyses showed that dogs universally share a common homogenous gene pool containing 10 major haplogroups.
However, the full range of genetic diversity, all 10 haplogroups, was found only in southeastern Asia south of Yangtze River, and diversity decreased following a gradient across Eurasia, through seven haplogroups in Central China and five in North China and Southwest SWAsia, down to only four haplogroups in Europe.
The mean sequence distance to ancestral haplotypes indicates an origin 5,400–16,300 years ago ya from at least 51 female wolf founders. These results indicate that the domestic dog originated in southern China less than 16,300 ya, from several hundred wolves.
The place and time coincide approximately with the origin of rice agriculture, suggesting that the dogs may have originated among sedentary hunter-gatherers or early farmers, and the numerous founders indicate that wolf taming was an important culture trait.
Tree tuesday: The global human mitochondrial tree
This is a picture of the global human mitochondrial tree from mitomap.org. The full-sized image is here (large!).
Evidence that two main bottleneck events shaped modern human genetic diversity — Proceedings B
Evidence that two main bottleneck events shaped modern human genetic diversity — Proceedings B
There is a strong consensus that modern humans originated in Africa and moved out to colonize the world approximately 50 000 years ago. During the process of expansion, variability was lost, creating a linear gradient of decreasing diversity with increasing distance from Africa. However, the exact way in which this loss occurred remains somewhat unclear: did it involve one, a few or a continuous series of population bottlenecks? We addressed this by analysing a large published dataset of 783 microsatellite loci genotyped in 53 worldwide populations, using the program ‘Bottleneck’. Immediately following a sharp population decline, rare alleles are lost faster than heterozygosity, creating a transient excess of heterozygosity relative to allele number, a feature that is used by Bottleneck to infer historical events. We find evidence of two primary events, one ‘out of Africa’ and one placed around the Bering Strait, where an ancient land bridge allowed passage into the Americas. These findings agree well with the regions of the world where the largest founder events might have been expected, but contrast with the apparently smooth gradient of variability that is revealed when current heterozygosity is plotted against distance from Africa.
The Phantom of Heilbronn and DNA testing.
Oops:
Police in Germany have admitted that a woman they have been hunting for more than 15 years may never have existed. Dubbed the "phantom of Heilbronn", the woman was dubbed by police as the country's most dangerous woman. Investigators had connected her to six murders and an unsolved death based on DNA traces found at the scene.
Melanism in evolution
Sean Carroll in The Smithsonian Magazine talks about how the alternative color forms of some animals are providing new insights into how animals adapt and evolve:
One of the most widespread phenomena in the animal kingdom is the occurrence of darkly pigmented varieties within species. All sorts of moths, beetles, butterflies, snakes, lizards and birds have forms that are all or mostly black. Perhaps most familiar are the dark big cats, such as the black leopard and black jaguar. These beautiful animals are often displayed in zoos as curiosities, but they also occur in the wild in significant numbers.
Phylogenetics in the NY Times
The NY Times has a nice article on phylogenetic tree visualisation. Yes, really:
For years now the researchers have sequenced DNA from thousands of species from jungles, tundras and museum drawers. They have used supercomputers to crunch the genetic data and have gleaned clues to how today’s diversity of baobobs, dandelions, mosses and other plants evolved over the past 450 million years. The pace of their progress gives Dr. Sanderson hope that they will draw the entire evolutionary tree of plants within the next few years. “It’s within striking distance,” Dr. Sanderson said.
There’s just one problem. “We have no way to visualize such a tree at the moment,” he said. If they tried, they would end up with a blurry, inscrutable thicket. “It would be ironic,” Dr. Sanderson said. “We’d be saying, ‘We’ve built it, but we can’t show it to you.’
Is there more to heredity, natural selection, and evolution than genes and DNA
Eva Jablonka asks if there is more to heredity, natural selection, and evolution than genes and DNA?:
Growing evidence indicates there is more to heredity than DNA, that heritable non-DNA variations can take place during development, sometimes in response to an organism's environment. The notion of soft inheritance is returning to reputable scientific inquiry. Moreover, there seem to be cellular mechanisms activated during periods of extreme stress that trigger bursts of genetic and non-genetic heritable variations, inducing rapid evolutionary change. These realizations promise to profoundly alter our view of evolutionary dynamics.