Genetic infrapopulation sizes in blood parasites: a pilot quantification of the bottleneck in louse fly vectors

IF 2.4 3区环境科学与生态学 Q2 ECOLOGY

Frontiers in Ecology and Evolution Pub Date : 2024-04-09 DOI:10.3389/fevo.2024.1319829

Kai Fischer, Nayden Chakarov

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Abstract

IntroductionBottleneck events are crucial for the strength of genetic drift, selection and speed of evolution. They are believed to play a particularly prominent role for parasitic infrapopulations, inhabiting single host individuals, which are often established by very few parasite individuals during transmission. In vector-borne pathogens, the bottlenecking effects can even be serialized through repeated filtering of parasitic stages at different tissues and organs of the vector. Using qPCR we aimed to quantify the number of potentially transmittable sporozoites of the hemosporidian blood parasite Haemoproteus columbae in the specialized vector louse flies Pseudolynchia canariensis which transmit these parasites between house pigeon hosts Columba livia.ResultsBased on qPCR measurements of organ-derived DNA of individual louse flies, we estimate that the midgut of these vectors contains on average 20 parasites, the hindgut and other intestines ca. 50 parasites and the salivary glands ca. 5 parasite cells. Nearly one third of all vector individuals appeared to lack parasite DNA, despite having only infected hosts as blood meal sources. The magnitude of parasite numbers in midgut and salivary glands tended to correlate positively.DiscussionOur results indicate, potential severe bottlenecking of parasite populations during individual transmission events and a probable effect of individual vector immunity on this variable. However, this may be partly alleviated by the coloniality of house pigeons, the frequency of louse flies and their daily feeding events in most populations, leading to repeated transmission opportunities, decreased quasi-vertical transmission between parents and offspring and probable panmixia of Haemoproteus columbae lineages. Many of these mechanisms might not apply in other host-vector systems. We propose several additional molecular and microscopical tools to improve the accuracy of estimating parasite population sizes in vectors and call for more estimations in different vector species to better understand the co-evolution between malaria-like blood parasites and their avian and insect hosts.

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血液寄生虫的遗传种群规模：对虱蝇媒介瓶颈的试点量化

导言瓶颈事件对于遗传漂变的强度、选择和进化速度至关重要。人们认为，瓶颈事件在寄生于单一宿主个体的寄生虫种群中发挥着特别重要的作用，这些种群往往是由极少数寄生虫个体在传播过程中建立起来的。在病媒传播的病原体中，瓶颈效应甚至可以通过在病媒的不同组织和器官中寄生阶段的重复过滤而序列化。我们使用 qPCR 方法，旨在量化在家鸽宿主 Columba livia 之间传播血孢子虫血液寄生虫 Haemoproteus columbae 的专门载体虱蝇 Pseudolynchia canariensis 中潜在的可传播孢子虫数量。结果根据对虱蝇个体器官衍生 DNA 的 qPCR 测量，我们估计这些载体的中肠平均含有 20 个寄生虫，后肠和其他肠道含有约 50 个寄生虫，唾液腺含有约 5 个寄生虫细胞。近三分之一的媒介个体似乎缺乏寄生虫 DNA，尽管它们只有受感染的宿主作为血餐来源。中肠和唾液腺中寄生虫数量的大小往往呈正相关。讨论我们的研究结果表明，在个体传播事件中，寄生虫种群可能会出现严重的瓶颈现象，而个体载体免疫力可能会对这一变量产生影响。然而，家鸽的群居性、虱蝇的出现频率以及它们在大多数种群中的日常觅食活动可能会部分缓解这种情况，从而导致重复的传播机会、亲代与子代之间的准垂直传播减少以及褐血病菌系的可能泛混性。其中许多机制可能不适用于其他宿主-媒介系统。我们提出了几种额外的分子和显微镜工具，以提高估计病媒中寄生虫种群数量的准确性，并呼吁对不同病媒物种进行更多的估计，以更好地了解类疟疾血液寄生虫与其禽类和昆虫宿主之间的共同进化。

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来源期刊

Frontiers in Ecology and Evolution Environmental Science-Ecology

CiteScore

4.00

自引率

6.70%

发文量

1143

审稿时长

12 weeks

期刊介绍： Frontiers in Ecology and Evolution publishes rigorously peer-reviewed research across fundamental and applied sciences, to provide ecological and evolutionary insights into our natural and anthropogenic world, and how it should best be managed. Field Chief Editor Mark A. Elgar at the University of Melbourne is supported by an outstanding Editorial Board of international researchers. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics and the public worldwide. Eminent biologist and theist Theodosius Dobzhansky’s astute observation that “Nothing in biology makes sense except in the light of evolution” has arguably even broader relevance now than when it was first penned in The American Biology Teacher in 1973. One could similarly argue that not much in evolution makes sense without recourse to ecological concepts: understanding diversity — from microbial adaptations to species assemblages — requires insights from both ecological and evolutionary disciplines. Nowadays, technological developments from other fields allow us to address unprecedented ecological and evolutionary questions of astonishing detail, impressive breadth and compelling inference. The specialty sections of Frontiers in Ecology and Evolution will publish, under a single platform, contemporary, rigorous research, reviews, opinions, and commentaries that cover the spectrum of ecological and evolutionary inquiry, both fundamental and applied. Articles are peer-reviewed according to the Frontiers review guidelines, which evaluate manuscripts on objective editorial criteria. Through this unique, Frontiers platform for open-access publishing and research networking, Frontiers in Ecology and Evolution aims to provide colleagues and the broader community with ecological and evolutionary insights into our natural and anthropogenic world, and how it might best be managed.