Dissertation Research: Quantitative Genetics of a Parasitic Wasp

在大多数物种中，儿子和女儿的数量是相等的，这种 1:1 的性别比例通常出现在拥有大量随机交配群体的动物中。 甚至性别比例也是染色体性别决定的结果（例如哺乳动物，雌性为 XX，雄性为 XY）。 在具有这种性别决定的动物中，性别比例很少或没有遗传变异。 然而，在膜翅目（蜜蜂、蚂蚁和黄蜂）中，性别并不是以这种方式决定的。雌性后代由受精卵产生，雄性后代由未受精卵产生。 寄生黄蜂的性别比例通常不是 1:1。 寄生黄蜂的宿主分布在斑块中，因此斑块中的后代之间的交配并不是随机的。 当整个种群中的交配不是随机的时，没有理由产生比使所有雌性受精所需的数量更多的儿子，因此理论上预期的性别比是偏向雌性的。 此外，理论预测，即使性别比例偏向女性，性别比例也几乎不存在遗传变异。 尽管有理论上的预测，性别比例的遗传变异已在许多寄生黄蜂中得到证实。 食蝇猛禽是一种攻击各种蝇类蛹的黄蜂。 它用于家禽养殖场和牛饲养场的家蝇和马厩蝇的生物防治。 研究人员将进行一系列实验，描述性别比例的遗传变异以及相关特征，如终生繁殖力、寿命和后代的存活率。 还将研究维持性别比遗传变异的机制。 这项研究还适用于生物控制，因为它将指出性别比例的人工选择将如何影响其他性状，并确定偏好的性状是否在所有环境中均等表达。

In most species, the numbers of sons and daughters are equal, and this 1:1 sex ratio is found generally in animals with large, randomly mating populations. Even sex ratios are a consequence of chromosomal sex determination (e.g. mammals, in which females are XX and males are XY). In animals with this kind of sex determination, there is little or no genetic variation for sex ratio. In Hymenoptera (bees, ants and wasps), however, sex is not determined in this way; female offspring arise from fertilized eggs, and males arise from unfertilized eggs. Sex ratios that regularly differ from 1:1 are found in parasitic wasps. The hosts of parasitic wasps are distributed in patches, so mating among the offspring from a patch is not random. When mating is not random throughout a population, there is no reason to produce more sons than are necessary to inseminate all the females, so the theoretically expected sex ratio is female-biased. Furthermore, theory predicts that there will be little genetic variation in sex ratio even when sex ratio is female-biased. Despite theoretical predictions, genetic variation in sex ratio has been demonstrated in a number of parasitic wasps. Muscidifurax raptor is a wasp that attacks the pupae of various fly species. It is used for biological control of houseflies and stableflies at poultry farms and cattle feedlots. The investigators will conduct a series of experiments that will describe the genetic variation in sex ratio and related characters like lifetime fecundity, longevity, and survival of offspring. Mechanisms that could maintain genetic variation for sex ratio will also be examined. This research also has applications for biological control because it will point out how artificial selection for sex ratio will affect other traits, and determine whether favored traits are expressed equally in all environments.