Sexual selection and the MHC in the fowl

家禽的性选择和 MHC

• 批准号: NE/D003865/1
• 负责人: Tommaso Pizzari
• 金额: $ 14.06万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD003865%2F1
• 关键词: Sexual; selection; MHC; fowl

In many species females prefer to mate with specific males. In addition, when they mate with multiple males, females often favour fertilisation by the sperm of specific partners. Why do females favour certain males over others? It has been suggested that females may select males that carry genes which help the individual cope with their environment and by doing so the females thereby obtain the same high quality paternal genes for her young. This idea remains contentious and little tested. The major histocompatibility complex (MHC) is a group of genes that help determine resistance to parasites and diseases in higher animals (i.e. vertebrates, including humans). The type and variety of MHC genes an individual carries determine how well they can cope with parasites and diseases. Females may therefore increase the health of their offspring by selecting mates on the basis of MHC characteristics. This may happen in three different ways. First, females may favour fertilisations by males carrying an MHC that is different from their own. This will ensure that the offspring will inherit many different types of MHC genes (alleles) from their parents, and thus will be able to defend themselves from a wider range of diseases. Second, females may increase the MHC diversity of the offspring by favouring males that have a diverse MHC. Third, females may prefer males carrying specific MHC genes that provide more efficient resistance against diseases than other MHC types currently available. Understanding how MHC diversity influences reproduction is important for our understanding of the evolution of female mate choice, male sexual ornaments (e.g. stags antlers) and reproductive strategies. It may also allow us to better manage fertilisation and fertility problems in domestic and pest species and in species at risk of extinction. Despite much interest in the MHC and reproductive behaviour, the mechanisms through which the MHC may influence reproductive success remain unresolved. Our proposed research investigates the role of the MHC in the reproductive strategies of birds, and aims to determine if and how the different possible MHC-based mechanisms outlined above operate at specific reproductive stages: from mate choice to the selection of sperm within the female reproductive tract after insemination. We will study two semi-natural populations of fowl, Gallus gallus. The fowl is an ideal animal to study for two important reasons. First, it is a model system of reproductive physiology and behaviour and much is known about the mechanisms that determine mating and fertilisation success. Second, the MHC of the fowl is relatively small and easy to study. This has enabled extensive studies of the fowl MHC and its associations with disease resistance: more is known about the link between the MHC and diseases in the fowl than in any other animal. We will first: (a) determine how the MHC of males and/or their similarity with the females MHC females accounts for differences between the reproductive success of different males in small natural groups, (b) experimentally investigate how much the MHC determines male traits (e.g. social status, comb size and sperm quality) which influence a males ability to mate with females, and the fertilising efficiency of their ejaculates, (c) experimentally test whether female preference for certain mates is explained by MHC mechanisms. We will then focus on events occurring during/after insemination, by testing whether: (e) males invest more sperm in certain females based on female MHC characteristics, (f) females preferentially utilise the sperm of certain partners based on male MHC characteristics, and (g) the outcome of the competition between ejaculates that occurs when females copulate with multiple males (as it normally happens in the fowl), is determined by the MHC characteristics of males involved.

在许多物种中，雌性喜欢与特定的雄性交配。此外，当它们与多个雄性交配时，雌性往往倾向于通过特定伴侣的精子受精。为什么女性偏爱某些男性？有人认为，雌性可能会选择携带有助于个体科普环境的基因的雄性，通过这样做，雌性从而为她的后代获得相同的高质量父系基因。这一想法仍然存在争议，几乎没有经过检验。主要组织相容性复合体（MHC）是一组有助于决定高等动物（即脊椎动物，包括人类）对寄生虫和疾病的抵抗力的基因。一个人携带的MHC基因的类型和种类决定了他们如何科普寄生虫和疾病。因此，雌性可以通过根据MHC特征选择配偶来增加后代的健康。这可能以三种不同的方式发生。首先，雌性可能更喜欢与携带不同于自己的MHC的雄性受精。这将确保后代将从父母那里继承许多不同类型的MHC基因（等位基因），从而能够保护自己免受更广泛的疾病。第二，女性可能会增加MHC多样性的后代，有利于男性，有一个不同的MHC。第三，女性可能更喜欢携带特定MHC基因的男性，这些基因比目前可用的其他MHC类型更有效地抵抗疾病。了解MHC多样性如何影响生殖对于我们理解雌性择偶、雄性性装饰物（如鹿角）和生殖策略的进化具有重要意义。它还可以让我们更好地管理家养和有害物种以及濒临灭绝物种的受精和生育问题。尽管对MHC和生殖行为有很大的兴趣，但MHC可能影响生殖成功的机制仍然没有得到解决。我们提出的研究调查了MHC在鸟类生殖策略中的作用，旨在确定上述不同的可能的基于MHC的机制是否以及如何在特定的生殖阶段运作：从交配选择到受精后雌性生殖道内的精子选择。我们将研究两个半自然种群的家禽，原鸡。家禽是一种理想的研究动物，有两个重要原因。首先，它是生殖生理和行为的模型系统，并且对决定交配和受精成功的机制有很多了解。其次，鸡的MHC相对较小，易于研究。这使得对家禽MHC及其与疾病抵抗力的关系的广泛研究成为可能：对家禽MHC与疾病之间的联系的了解比任何其他动物都多。我们将首先：（a）确定雄性的MHC和/或它们与雌性MHC雌性的相似性如何解释小的自然群体中不同雄性的生殖成功之间的差异，（B）实验研究MHC在多大程度上决定雄性性状（例如社会地位、梳子大小和精子质量），这些因素影响雄性与雌性交配的能力，以及它们射精的受精效率，（c）通过实验测试女性对某些配偶的偏好是否可以用MHC机制来解释。然后，我们将重点关注授精期间/之后发生的事件，通过测试是否：（e）基于女性MHC特征，男性将更多精子投入某些女性，（f）基于男性MHC特征，女性优先利用某些伴侣的精子，以及（g）当女性与多个男性交配时发生的射精之间竞争的结果（因为它通常发生在家禽中），是由所涉及的雄性MHC特征决定的。

项目成果

The measure and significance of Bateman's principles.

• DOI: 10.1098/rspb.2013.2973
• 发表时间: 2014-05-07
• 期刊: Proceedings. Biological sciences
• 作者: Collet JM;Dean RF;Worley K;Richardson DS;Pizzari T
• 通讯作者: Pizzari T

Within-group male relatedness reduces harm to females in Drosophila.

• DOI: 10.1038/nature12949
• 发表时间: 2014-01-30
• 期刊: Nature
• 影响因子: 64.8
• 作者: Carazo P;Tan CK;Allen F;Wigby S;Pizzari T
• 通讯作者: Pizzari T