The latest edition of a relatively new blog carnival called Oekologie — very groovy — is up at Behavioral Ecology Blog. There’s not an awful lot of direct agricultural interest. A post from GrrrlScientist summarizes a study on the evolution of Soay sheep on the island of Hirta in the Outer Hebrides (not) near Scotland. Cold winters select larger sheep, which selects for fewer sheep. But not all winters are that cold. On the indirect front, there are an awful lot of posts on climate change, including the one from our own Andy Jarvis, which Oekologie compiler Matt admits he found “too depressing … to read”. Shame on you Matt, but thanks for the carnival.
Transgenic salmon
One of the major concerns about transgenic plants and animals has always been that they could escape and that transgenes could then spread into wild populations with mostly unforeseeable consequences. ((Contribution by Michael Kubisch)) For most farmed animal species, cattle, goats or sheep for example, this is not much of a problem because there are no true wild populations with which escapees could hybridize. However, farmed fish, such as salmon or catfish, do have wild relatives, reproduce relatively fast and farmed fish do occasionally escape into the wild, even in large numbers. This has led to a number of estimates and models of what impact such transgenic escapees might have on resident fish populations or on their prey species.
A recent article tells a cautionary tale about the value of such predictions by demonstrating that advantages which transgenic animals have “down on the farmâ€, such as a faster growth rate if they carry extra copies of the growth hormone (GH) gene, may in fact be less obvious  in the wild. The article describes a study in which GH-transgenic and wild-caught coho salmon were compared in either a conventional hatchery or a simulated natural environment. Under hatchery conditions, in which fish were fed a commercially available diet, the transgenic salmon grew to nearly three times the size of their wild cousins. However, in the natural environment, in which fish were exclusively fed natural food items, transgenics had only a 20% weight advantage. When the salmon were introduced to prey species, in this case trout fry, the impact of transgenic animals on their prey was reflective of their environment and size and the impact of transgenics on prey was much reduced.
While this says relatively little about the actual impact of transgenic escapees on resident fish populations, it does show that accurate predictions may be much harder to come by than previously assumed.
Hai chihuahua!
A DNA study suggests that small dogs started to appear about 10,000 years ago as a result of a mutation in a single gene (called IGF-1). I wonder if something similar will be found in other domestic animals.
Happy Easter!
Did you know there was such a thing as a Sumatran striped rabbit?
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