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What's the difference between genome-wide data and mitochondrial genomes?
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[QUOTE]Originally posted by the lioness,: [QB] [QUOTE]Originally posted by Elmaestro: [qb] [i]"That chart does not represent all Africans and it is the percentage that a certain branch is found in 10000 bootstrapped trees"[/i] ^mind elaborating on what this means lioness? Or even Xyyman, you wanna take a go at it? In laymans language... [/qb][/QUOTE] http://gogarten.uconn.edu/mcb221_2006/class30.html Bootstrapping is one of the most popular ways to assess the reliability of branches. The term bootstrapping goes back to the Baron Münchhausen (pulled himself out of a swamp by his shoe laces). Briefly, positions of the aligned sequences are randomly sampled from the multiple sequence alignment with replacements.? The sampled positions are assembled into new data sets, the so-called bootstrapped samples. Each position has an about 63% chance to make it into a particular bootstrapped sample. If a grouping has a lot of support, it will be supported by at least some positions in each of the bootstrapped samples, and all the bootstrapped samples will yield this grouping. Bootstrapping can be applied to all methods of phylogenetic reconstruction. Bootstrapping thus realizes the impossible: the evolution of sequences in real life happened only once, and it is impossible to run the evolution of, let's say, small subunit ribosomal RNAs again. Nevertheless, using the resampling approach, pseudosamples are generated that have a variation that resembles the variation one would have obtained, if it were possible to sample 100 or 1000 parallel worlds in which the evolution of 16S rRNAs occurred over and over again. You end up with a statistical analyses using a single original sample only. Bootstrapping has become very popular to assess the reliability of reconstructed phylogenies. Its advantage is that it can be applied to different methods of phylogenetic reconstruction, and that it assigns a probability-like number to every possible partition of the dataset (= branch in the resulting tree). Its disadvantage is that the support for individual groups decreases as you add more sequences to the dataset, and that it just measures how much support for a partition is in your data given a method of analysis. If the method of reconstruction falls victim to a bias or an artifact, this will be reproduced for every of the bootstrapped samples, and it will result in high bootstrap support values. Some researchers such as a person known as xyyman on the Egyptology forum, Egyptsearch have no straps on their boots. This leads to the boots falling off and has been an ongoing problem in such approaches [QUOTE]Originally posted by xyyman: The distance between ALL AFRICANS and EUROPEANS is 77.[/QUOTE]^ In other words, wrong in two different was --------------------------------------------------- [i]correcting xyyman is a full time job[/i] [/QB][/QUOTE]
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