网范文：“A more systematic approach to biological risk ” 自世纪之交以来,DNA测试已经帮助建立生物血统的姓氏和家谱。以前没有直接证据,每个大家庭聚集在一起。然而,DNA测试提供证据来帮助说明，尤其是规模大的中世纪父系血统家族。在这篇生物范文中，讲述了对于DNA测试的问题，执行一些相关的DNA结果的统计略论，英语论文题目，这使我们能够比较DNA结果，预测一些重要的信息。不过考虑到移民问题,我们最初假设它随机发生，英语论文，虽然我们找到一些可能的证据表明大血统的家庭迁移比例比较小。
Abstract
Since the turn of the millennium, DNA testing has helped with establishing the sizes of biological descent families within surnames. Some surnames have a dominant family: their remaining populations can be ascribed either to NPEs (non paternity events) or to smaller separate-origin families. Previously, there was no direct evidence as to how large each male-line family could grow within a surname, considering that real-life plural-origin surnames could contain a few or many separate-origin families of various sizes. However, DNA testing is providing evidence to help indicate in particular the size of the largest male-line medieval descent family in a surname. We here perform statistical analyses of some relevant DNA results.
This allows us to compare the DNA results with some predicted findings from our computer simulations. We thereby surmise that moderately common surnames, with UK populations around ten thousand or so, are likely to be plural-origin, comprising a handful of separate-origin descent families. As limiting examples, Sykes and Plant are at the extreme of having a large DNA descent cluster, whereas Bray and Jefferson lie at the opposite extreme with only a small largest cluster. We also proceed to consider very common and prolific surnames, with UK populations exceeding the order of a hundred thousand people.
For these, the sizes of their descent clusters are fractionally very small and accordingly sensitive to sample bias. This places more reliance on the computer model predictions for such surnames. We model general trends for a range of surname sizes. For considering emigration overseas, we initially assume that it occurs randomly though we find some possible evidence that large descent families might migrate disproportionately more than smaller ones.
Introduction
We earlier presented computer simulations for the growth of populous single-origin families1 and we here extend our computer model. We also broaden our deliberations, comparing our simulation predictions with observations for some real surnames whose component family populations are derived partly from previously published DNA data. whereas the familial descendants involve the transfer of the surname to children who are not necessarily true paternal descendants of a male bearer of the name.
This is a key aspect of our interpretations of the DNA data which are obtained from DNA tests on the Y-chromosomes of living male bearers of the surname. Only male-line biological descendants inherit the surname progenitor’s Y-chromosome; his additional familial descendants inherit, typically through a female link, his surname but not his Ychromosome. The additional component of familial descent in a medieval descent family of a surname arises because of, for example, the family adopting a differently fathered child, or the introgression of a differently fathered child into the family name through a concealed wifely infidelity, or an unmarried mother in the family passing on her own surname to her child of different paternity.
We shall here talk in particular about the "male-line descendants of a medieval man" or, in other words, his "male-line descent family". Considering either the biological or the fuller familial descent, we can consider that there could be several different contributing descent families that make up the total population of a plural-origin surname: we shall refer to each family as a "single-origin descent family" or a “separate-origin family”. By this, we generally mean a surviving descent family from late medieval times whose single origin was when the surname first formed.
It is possible that several biological descent families will match at the level of resolution of the data, particularly when using DNA data that has only measured a limited number of Y-chromosome markers. As discussed further below, these several conflated biological descents can be indistinguishable from the assumption that a single large biological family makes up the DNA “descent cluster”. By a “descent cluster” , we mean a set of matching or almost matching Ychromosome values. For each cluster, we can talk of its Y-DNA signatures which match or nearly match. A cluster is normally taken, when measured with adequate DNA resolution, to represent a single descent family but it might represent several, particularly if the cluster’s Y-DNA signatures are common in the general population such that it might contain accidental matches to unrelated men.()
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