tag:blogger.com,1999:blog-37148773.post7891347448936049922..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: Do Invasive Mitochondria Spread by Drift or Selection?Larry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-37148773.post-53049150058735547982012-07-26T10:03:02.126-04:002012-07-26T10:03:02.126-04:00What I am saying is that the "intogression ra...What I am saying is that the "intogression rate" is probably similar - 1 mtDNA and 1/2 the ncDNA per mating (like the type in the polar bear x brown bear or human x neandertal stories). Without invoking some strange ring species, I can't see how you would get the mtDNA without the ncDNA. <br /><br />What we are seeing is that the mtDNA persists or is detected more. Is this due to some inherent property (as Coyne and Hawks seem to be saying) or is it just due to the pop-gen differences after the event?<br /><br />-The Other JimAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-40952077092467777422012-07-26T09:21:34.672-04:002012-07-26T09:21:34.672-04:00Sure. But a detection bias is a different claim. A...Sure. But a detection bias is a different claim. Also, wouldn't that be somewhat offset by the greater rate at which introgressing mtDNA goes extinct? That is, re-fixation of the original species haplotype would proceed at a higher rate too.john harshmannoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-22209283510339634832012-07-26T09:19:12.111-04:002012-07-26T09:19:12.111-04:00The problem I see is of that of shoehorning closel...The problem I see is of that of shoehorning closely related species to a single bifurcating 'true' tree. Each marker has a genealogy and each genealogy reflects the ancestry accurately. A bifurcating tree is - when closely related species are concerned - at best a gross statistical approximation. Polar bears mated with brown bears and neandertals with humans, this is not an 'error', it reflects a proportion of the ancestry and it enriches our understanding of population history. Haven't we learned this or are we still seeing species as 'purebreeds' and introgression as something better to forget about. Population histories are messy, they are not bifurcating trees. Hawks and Coyne are talking of population history not phylogeny, so dismissing mtDNA for the whole of its use in phylogenetics because it does not reflect population history is not a lesson in biology, it is at best shortsightedness.Africa Gomezhttps://www.blogger.com/profile/03501193251810926737noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-9483898892723423982012-07-26T01:37:18.687-04:002012-07-26T01:37:18.687-04:00Assuming the same rate of introgression (the ncDNA...Assuming the same rate of introgression (the ncDNA and mtDNA from one mating) Would fixation rate not have an effect on the probability of observation? Remember these studies are only based on a handful of organisms per group. An allele present in 5% of the population would be missed while one in over half would be detected.<br /><br />-The Other JimAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-60763323728003863562012-07-25T20:13:00.953-04:002012-07-25T20:13:00.953-04:00Speed of fixation and frequency of introgression a...Speed of fixation and frequency of introgression are two separate issues. The claim is that mtDNA introgresses more often than nuclear DNA. If that's true, I didn't know it, and I would certainly like to know why. Faster coalescence wouldn't seem to affect anything. We want to know about the probability of fixation for introgressive DNA, not the speed of fixation.john harshmannoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-38439614866201622262012-07-25T15:59:42.743-04:002012-07-25T15:59:42.743-04:00The part they both seem to be missing is that in t...The part they both seem to be missing is that in the human-Neandertal case, ~4% of the ncDNA and ~11% in that bear paper also would have been similarly misleading. Given that mtDNA has been far more frequently used in animal phylogenetics, are we just seeing a sampling bias?<br /><br />I think people "know" that the haploid, maternally inheritance of the mtDNA will increase the probability of a given allele fixing via drift due to the reduced <i>Ne</i>. Whether they remember this when writing is another question. <br /><br />-The Other JimAnonymousnoreply@blogger.com