Evolution of mating tactics and reproductive strategies in protozoan parasites

原生动物门(Apicomplexa)包括一些对牲畜和人类最严重的病原体。尽管进行了广泛的资金努力，但我们对它们为最大限度地繁殖成功而演变的策略知之甚少。这些寄生虫，包括疟疾(疟原虫)寄生虫，必须在其媒介内经历一轮有性繁殖，才能传播给新的宿主。一旦进入媒介的血液中，性阶段就会迅速分化为配子，雄配子和雌配子之间就会发生受精。然而，血餐是一个非常恶劣的交配环境，因为血液正在迅速冷却和凝结。这也使配子暴露在宿主的免疫因素和媒介的消化化学物质之下。因此，男性性阶段最多有20分钟的时间离开他们的红细胞，分化成配子，并找到雌性受精。此外，与大多数其他雄性动物不同，雄性疟疾寄生虫最多只能产生8个配子。这使得疟疾寄生虫的交配系统非常新颖，然而，可用的数据非常少，重要的问题仍然没有答案。这项建议将发现疟疾寄生虫之间的交配是如何受到宿主免疫因素的影响，询问雄性是随机寻找雌性还是可以找到它们的位置，并将调查共同感染疟疾寄生虫的物种如何保持其物种身份。更好地了解生物体如何以及为什么采用我们观察到的策略，可以从根本上洞察适应的过程，并在从医学到保护的各个领域具有宝贵的实际应用。鉴于疟疾寄生虫的医疗和经济重要性，以及开发传播阻断疫苗和干预战略的动力，从进化和生态角度理解这一过程至关重要。

The Phylum Apicomplexa (Protozoa) includes some of the most serious pathogens of livestock and humans. Despite extensive funding efforts, we understand remarkably little about the strategies they have evolved in order to maximise their reproductive success. These parasites, including malaria (Plasmodium) parasites, must undergo a round of sexual reproduction inside their vectors in order to transmit to new hosts. Once inside a vector's blood meal, sexual stages rapidly differentiate into gametes and fertilisation between male and female gametes occurs. However, a blood meal is a very harsh environment to be mating in, as blood is rapidly cooling and clotting. This also exposes gametes to both their host's immune factors and their vector's digestive chemicals. Consequently, male sexual stages have a maximum of 20 minutes to exit their red blood cells, differentiate into gametes and find females to fertilise. Furthermore, unlike most other male animals, male malaria parasites can only produce a maximum of eight gametes. This makes the mating system of malaria parasites very novel, yet, there is remarkably little data available and important questions remain unanswered. This proposal will discover how mating between malaria parasites is influenced by host immune factors, ask whether males randomly search for females or can home in on their location, and will investigate how co infecting species of malaria parasite maintian their species identity. A greater understanding of how and why organisms adopt the strategies we observe provides fundamental insights into the process of adaptation, as well as having valuable practical applications in areas ranging from medical science to conservation. Given the medical and economic importance of malaria parasites and the drive to develop transmission blocking vaccines and intervention strategies, understanding this process from an evolutionary and ecological perspective is of crucial importance.