Category: Livestock

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Reindeer, caribou, genetics and global warming

Reindeer (Rangifer tarandus tarandus) were domesticated probably around 20,000 years ago in northern Europe and Asia. They are still kept by many herders in the Eurasian Arctic, who derive their livelihood from their animals. Reindeer from Siberia were imported into Alaska in the late 19th century in an attempt to provide income for indigenous people. In the 1930s an estimated 600,000 reindeer existed in Alaska, but that number is now down to about 20,000. It seems that most people didn’t quite see the point of managing reindeer when all they had to do was go out and hunt its wild cousin, the caribou (Rangifer tarandus granti). One of the unforeseen consequences of this endeavor has been the migration of reindeer into caribou herds and until recently it was unknown to what extent this influx has had an impact on the genetic diversity of caribou. A recent analysis of microsatellite DNA in caribou and reindeer in Alaska, however, shows that very little genetic introgression seems to have taken place into either species and the authors think the reason could be that hybrid offspring may have a lower chance of survival. It is interesting to note that their study also indicates that the Alaskan/Russian reindeer and the Alaskan and Canadian caribou are much more closely related to each other than either is to the Scandinavian reindeer.

Caribou, which can be found throughout Alaska and the Canadian territories, migrate often in large herds between their summer and winter pastures. The porcupine herd, for example, numbers in excess of 100,000 animals and covers a distance of over 2000 km on its yearly route from the Yukon to the calving grounds on the Alaskan Arctic coast (the very same area the US government is trying to open up for oil exploration).  Many native people in Canada and Alaska still depend on these animals for their survival and they are becoming concerned that increasing human development and global warming may either affect the size of caribou herds or change their migration patterns.

From Michael Kubisch

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Of dung, mites and llamas

Researchers are counting fossilized dung-eating mites in the sediments of an Andean lake to get an idea of the size of llama herds in the surroundings, and thus “reconstruct the fluctuating fortunes of local (human) populations for an era from which no written records exist.” It turns out that “mite numbers rise and fall in concert with well-documented socio-economic changes in the postconquest period.” The paper is in the Journal of Archaeological Science, but you can read a summary here.

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Water buffalo diversity

Michael Kubisch is a geneticist and reproductive physiologist working at the Tulane National Primate Research Center in the New Orleans area. He’s sent us his take on a recent paper on the genetics of the water buffalo. We really welcome this kind of contribution from our readers. Keep ’em coming! Here’s what Michael has to say:

Results of an interesting study by Chinese researchers have just been published, describing an extensive analysis of the genetics of Chinese swamp water buffalo (Bubalus bubalis). The Chinese swamp-type buffalo differs from the Indian river-type buffalo by the fact that it has 48 chromosomes compared to the 50 found in the latter. There is a third subspecies, the wild water buffalo, which may still exist in Southeast Asia, although its population size and genetic status are unknown and the animal is listed on the IUCN red list as being threatened. Based on analysis of mitochondrial DNA (which is solely inherited from one’s mother and consequently ideal for tracing maternal inheritance patterns), it appears that river and swamp buffalo split about 28,000 years ago with a further split in the swamp buffalo into two maternal lines taking place about 18,000 years ago. The genetic diversity varies between the two swamp buffalo matrilines in China and the authors suggest that the difference between the two lines might in part be due to the fact that occasional genetic introgression from wild swamp buffalo might have taken place into one of the lines. Interestingly, domestication of water buffalo seems to have occurred independently in India and China, most likely as a result of rice cultivation. Substantial numbers of water buffalo outside exist Asia, among other countries in Italy, where, as any cheese afficionado will know, their milk is used for the production of mozzarella.

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Wild sheep don’t drift

The moufflon is a wild sheep from Corsica, Sardina and Cyprus. In 1957, a male and a female from Corsica were taken to another island, this one in the southern Indian Ocean, in an attempt to establish a herd for sport hunting. The pair thrived on Haute Island, and the resulting population peaked at about 700 head in the 1970’s, thereafter oscillating between 200 and 600. Ok, so far so weird, but so what? Well it turns out that genetic diversity hasn’t behaved as expected. By rights in such a small, isolated, inbred population it should have decreased markedly as a result of genetic drift. But according to this, it hasn’t. The reason is probably strong natural selection, according to the authors of the study, who compared DNA from the original founding couple to that of the present herd.