Maintenance of ecological polymorphism by frequency-dependent selection

大多数物种在其种群中有一个单一的一般类型的个体，但在某些物种中，几个完全不同的类型共存。 最明显的例子是两性共存，这是因为两者都是繁殖所必需的。 我的研究是问不同的类型如何在每种性别中持续存在，在不同类型由于强烈的遗传差异而发生的情况下。 一种以上的雄性或雌性对于繁殖是不必要的。 为什么没有一种类型胜过另一种，使它灭绝？ 我正在探索这些问题，利用巨大的差异，身体大小，外观和行为，是由单一的遗传差异造成的一个非凡的滨鸟称为ruff。 大多数雄性皱领鸟都有奇特的繁殖羽毛，但是，在鸟类中是独一无二的，这些羽毛就像家猫的毛色一样个体可变。 不同颜色的鸟行为不同。 深色的鸟是领土性的，而浅色的鸟与主人分享繁殖领土。 雌性体型较小，缺乏华丽的羽毛。 值得注意的是，大约1%的雄性，被称为“雌性模仿者”，体型较小，缺乏华丽的羽毛，不向雌性展示，但仍然获得了繁殖成功。 我以前了解到，发展成一种或另一种男性类型是由两个基因的差异控制的。如此戏剧性的效果是不寻常的。在大多数情况下，许多相互作用的基因决定了这些特征的巨大差异。 我对这个有趣的物种的研究提出了这样一个问题：（1）控制这种或那种雄性行为、羽毛和体型发育的确切基因是什么？DNA处理技术的非凡进步使我们能够“找到控制这些功能的基因”。(2)这些相同的基因如何在男性和女性中表达不同呢？ 制造“女性模仿者”的基因也会减缓携带它的女性的繁殖，这似乎是不利的。可能因此，携带这种基因的鸟类中雄性的比例高于预期。(3)是什么控制了不同类型鸟类的性别比例差异？(4)不同类型的雄性是如何在种群中共存的？为什么没有一种类型的竞争对手？ 我的发现将帮助我们了解控制脊椎动物巨大体型、外观和行为差异的基本机制。这些在皱领中比在大多数其他动物中更容易研究，因为它们是由已知的遗传差异引起的。

Most species have a single general type of individual in their populations, but in some species, several quite different types co-exist. The most obvious examples is that two sexes coexist, which occurs because both are required for reproduction. My research is asking how different types persist within each sex, in cases where the different types occur due to strong genetic differences. More than one kind of male, or female, are not necessary for reproduction. Why doesn't one type outcompete the other, driving it to extinction? I am exploring these questions by taking advantage of large differences body size, appearance and behaviour that are caused by single genetic differences in an extraordinary shorebird called the ruff. Most male ruffs have fancy breeding plumages, but, uniquely among birds, these are as individually variable as the coat colours of domestic cats. Birds of different colours behave differently. Dark birds are territorial, while light birds share breeding territories with owners. Females are smaller, and lack fancy plumage. Remarkably, about 1% of males, called `female mimics', have small body sizes, lack fancy plumage, do not display to females, but nonetheless achieve breeding success. I have previously learned that development into one or another male type is controlled by differences at only two genes. Such dramatic effects are unusual. In most cases many interacting genes determine large differences in such characteristics. My studies with this intriguing species ask: (1) What are the exact genes that control development into one kind of male or another, for behaviour, plumage, and body size? Extraordinary advances in the technology for processing DNA is enabling us to 'find genes' that control such functions. (2) How do these same genes express themselves differently in males and females? The gene that makes 'female mimics' also slows down breeding by females that carry it, which seems disadvantageous. Possibly as a result, a higher proportion of birds than expected that carry this gene are males. (3) What controls the sex ratio differences of birds of different types? (4) How do different types of males co-exist in the population? Why doesn't one type out compete the others? My findings will help us understand demonstrate fundamental mechanisms controlling dramatic body size, appearance, and behavioural differences in a vertebrate. These are easier to study in ruffs than in most other animals because they are caused by known genetic differences.