Investigating an ongoing selective sweep: the dynamics and consequences of the spread of male-killer suppression in the butterfly Hypolimnas bolina

自然选择最为人所知的是生物体对人为变化的反应-工业化后花椒蛾的黑化，喷洒滴滴涕后的抗药性，细菌的抗药性。当然，自然选择也是随着自然环境的变化而发生的，尽管这种反应的节奏还没有很好地计算出来。在这项研究中，我们将检查对一种自然发生的寄生虫的持续选择性反应。这种寄生虫生活在蝴蝶宿主中，在那里它只杀死男性宿主(它是一种‘男性杀手’)。在最近的过去，出现了一种抑制这种寄生虫活动的物质，它‘拯救’了雄性宿主。在这项研究中，我们将研究这种抑制因子的传播，以及它对宿主的影响。在扩散方面，我们将检查抑制子最近出现的时间，以及它在地理上从源头扩散了多远--潜在地，该系统显示了迄今为止观察到的一些最快的动力学。在对宿主的影响方面，我们将研究这一新突变的传播如何影响基因组中的其他基因。基因集中在染色体上，就像链条上的珠子。当这些珠子中的一个被强烈选择时(就像我们的抑制子一样)，那么共享该链的基因的变体也可能受到与最初选择的突变的关联的影响。这个过程被称为搭便车旅行，因为一个人的运动携带着另一个人，而不是直接被选择的。因为在这种情况下选择是快速的，所以很可能许多其他基因也受到了影响。我们将检查这种情况发生的程度。从长远来看，人们希望这项研究也将有助于确定抑制基因的特征。这有可能a)帮助我们了解细菌毒素活性可能被阻断的方式，在医学生物学中具有潜在的用途b)鉴定该细菌产生的毒素，这将是一种在害虫和媒介控制中潜在有用的新型杀虫剂。

Natural selection is best known from the response of organisms to anthropogenic change-melanization of peppered moths after industrialization, resistance to insecticides after spraying with DDT, antibiotic resistance in bacteria. Natural selection, of course, happens in response to natural environmental change as well, although the tempo of the response is less well worked out. In this study, we will examine an ongoing selective response to a naturally occurring parasite. This parasite lives in butterfly hosts, where it kills male hosts only (it is a 'male-killer'). In the recent past, a suppressor of the activity of this parasite arose that 'rescues' male hosts. In this study, we will examine the spread of this suppressor, and its effects on the host. In terms of spread, we will examine how recently the suppressor arose, and how far it has spread from its source geographically-potentially the system displays some of the fastest dynamics observed to date. In terms of effect on the host, we will examine how the spread of this one new mutation affects other genes in the genome. Genes are grouped on chromosomes, like beads on a chain. When one of these beads is strongly selected (as is our supressor), so variants of genes that share the chain may also be affected by association with the orginal selected mutation. This process is termed hitch-hiking, as the movement of one carries along another that is not directly being selected. Because the selection is rapid in this case, it is likely that many other genes are also affected. We will examine the degree to which this is has occurred. In the long term, it is hoped the research will also help characterize the suppressor gene. This has the potential a) to help our understanding in the ways in which bacterial toxin activity might be blocked, with potential utility in medical biology b) to identify the toxin produced by this bacterium, which will represent a novel insecticidal agent of potential utility in pest and vector control.