Knabe,Your statement "positive selection increases the prevalence of adaptive traits. meaning man can influence this through selection without knowing it"confuses me. Are you implying that this is a problem? If so, I kindly disagree. i'm saying it can be a problem. selection for performance or other traits, could come at the expense of environmental adaptivity. i wonder what the dystocia rate of wildebeasts is? i wonder what it would be under selection pressure for depth of body, spring of rib, straight hocks, level hips, more bone, more hair, smaller head, polled, more rear, more sogginess, zipper fronted, rocket fronted, gain on grass, gain on grain. i wonder if parasite resistance, behavior such as migration in response to stimuli such as fly season is changed by performance selection. If you read the actual report, it is clear that the positive selection they are discussing is happening over millions of years on an evolutionary time scale, not likely due to artificial selection by humans. This selection may be do to ruminants having a rumen filled with microbes, or from the fact that they live in herds and diseases are easily passed between individuals. yes, it is clear, but the bottlenecks created in the last 200 years have decreased diversity as evidenced in the difference in diversity between indicus and taurus, with taurus under more recent bottlenecking and the removal of large segments of millions of years of selection. are you referring to microbe diversity in the rumen, or diversity within the microbe genome. there isn't much and it's difficult to influence, select for change in that. worked with a guy who's Ph.D. was specifically that.But, humans not knowing what genes they are affecting by selection has been occurring since cattle were domesticated 10,000 years ago. In fact, in order for a species to be domesticated, its genome must be altered in order that it will be docile enough to live with man. When you use EPDs to make selection decisions, you do not know the genes underlying that EPD, but the EPD still works with out problems. Hope this clarifies. if you read courageous cattlemen and responses to that direction, you will know that EPD's do not come without problems. i'm confused, other than domestication, which seems to be able to happen more quickly in some species than others, that if man simply picked out the easiest to domesticate way back in the day, they were picking out the animals that required on average, the least genetic change for domestication. it's not like they said, hey, lets make a controlled experiment, pick a diversity of animals that have various aversions to us.This is such an exciting day for the cattle community. Thanks for starting this post! With this new resource, mutations causing genetic deficts, such as Curly Calf, can be identified much more rapidly. The dairy industry is already using genomic breeding values, and in time the beef industry will follow. This means that we will know a calf's breeding value based on a DNA profile, rather than waiting years to record his progeny performance. This resource and the technologies that come from it will revolutionize the industry the same way EPDs, AI and ET have in the past. since i work for a company that is using genetic profiles, there is a danger there in that it is difficult to say do you have proof of absence of disease or just proof of no presence of disease or whatever trait you are working on in the opposite orientation for say a positive trait.which genetic changes have bottlenecked the genome the most? domestication, EPD's. evolutionary time scales are compressed by selection, or the equivalent of bottlenecking and creating essentially land races. human selection can and does overcome establishing heterozygosity.more later.
Article on genomic breeding valueshttp://genex.crinet.com/page2348/Genomics1
I feel that the HapMap paper showed that current levels of diversity are higher than expected and at the moment are fine. The problem comes when breeders are not concerned with inbreeding and diversity is substantually decreased.
Started by knabe The Big Show
Started by librarian The Big Show