Population Genomic Analysis of Introgression between Outcrossing and Selfing Plant Taxa

属于不同植物物种的个体通常不能相互交配以产生肥沃的种子。在这种情况下，物种保持彼此不同，不交换遗传物质。然而，某些物种对(约占所有植物的20%)，尽管它们的花和叶的形状非常不同，但它们能够交配并产生介于它们父母之间的杂交后代。如果这些杂交种能够产生花粉和种子，它们就可以与双亲交配。其结果是，一个物种的遗传物质被转移到另一个物种，而杂交物种扮演着中间人的角色。物种之间的遗传物质是共享的。被转移的遗传物质可能会影响受体物种的行为方式。例如，这可能意味着接受者比以前更能耐受内涝或低温，因为它从其他物种那里获得了这些特征。因此，物种之间的遗传物质转移不仅可能打破物种之间的差异，而且可能对使它们适应新的环境条件也非常重要，就像我们在气候变化下预期的那样。目前，我们知道有许多对植物物种可以相互交配并产生杂交后代。我们不知道的是这些物种之间交换了多少遗传物质，以及这在进化中有多重要。这项研究的目的是找出两种常见的开花植物水燕麦和木燕麦之间交换了多少遗传物质，这两种植物在英国许多地方形成了杂交。为了做到这一点，我们将在从未杂交的种群中查看这两个物种的遗传物质。我们将通过比较这两个物种的DNA序列，找出它们在遗传物质上的不同之处。然后，我们将对这两个物种的遗传物质进行排序，在它们已经杂交的地区，以及在它们共同生长但没有明显形成杂交的地区。DNA序列信息将告诉我们物种之间是否交换了遗传物质，交换了多少，以及遗传物质被转移到了哪个方向。对于我们这个物种，我们认为基因将从水燕麦转移到木燕麦上，因为水燕麦对传粉者更有吸引力，与杂交种交配的频率也比木燕麦更高。为了调查这个想法是否正确，我们将收集杂交种的后代和杂交区的双亲，并将它们长大。通过观察杂交后代的基因组成，我们将找出哪个亲本是种子的父亲，从而找出它是否像我们预测的那样优先与水燕子交配。我们获得的结果将首次给我们提供现代种群中杂交物种之间基因交换程度的定量概念。这将告诉我们杂交物种共享其遗传物质的程度，并将使我们能够评估当今杂交在植物进化和适应中的重要性。它可能会从根本上改变我们对植物物种作为离散和独特实体的本质的看法，并让我们看到今天在英国农村发生在我们周围的一个重要的进化过程。

Individuals belonging to different plant species are usually unable to mate with one another to produce fertile seed. In this situation the species remain distinct from one another and do not exchange genetic material. However certain pairs of species (some 20% of all plants), despite being very different in their flower and leaf shapes, are able to mate and produce hybrid offspring which are intermediate in form between their parents. If these hybrids can produce pollen and seed they can in turn mate with their parents. The outcome of this is that genetic material from one species is transferred to the other, with the hybrid acting as a go between. There is sharing of genetic material between the species. The genetic material that is transferred may affect the way the recipient species behaves. For instance it may mean that the recipient can tolerate waterlogging or low temperatures better that before because it has acquired these attributes from the other species. So transfer of genetic material between species may not only break down distinctions between species, it may also be very important in allowing them to adapt to new environmental conditions such as we expect under climate change. At present we know of many pairs of plant species which can mate with one another and produce hybrids. What we don't know is how much genetic material is exchanged between these species and how important this is in evolution. The aim of this research is to find out how much genetic material is exchanged between two common flowering plants, water avens and wood avens, which form hybrids in many places throughout Britain. In order to do this we will look at the genetic material of the two species in populations that have never hybridised. We will find out how the two species differ in their genetic material by comparing the sequences of their DNA. We will then sequence the genetic material of the two species in areas where they have hybridised, and in areas where they grow together but have not apparently formed hybrids. The DNA sequence information will tell us whether genetic material has been exchanged between the species, how much has been exchanged, and in which direction the genetic material is transferred. For our species we think that genes will be transferred from water avens to wood avens, because water avens is more attractive to pollinators and will mate more often with the hybrid than will wood avens. In order to investigate whether this idea is correct we will collect the offspring of hybrids and parents in hybrid zones, and grow them up. By looking at the genetic makeup of the hybrid's offspring we will find out which parent fathered the seed and therefore whether it has preferentially mated with water avens as we predict.The results we obtain will give us for the first time a quantitative idea of the extent of genetic exchange between hybridising species in present day populations. This will tell us the extent to which the hybridising species share their genetic material, and will allow us to assess the importance of present day hybridisation in the evolution and adaptation of plants. It may fundamentally change our ideas about the nature of plant species as discrete and distinct entities, and open our eyes to an important evolutionary process that is happening around us today in the British countryside.