Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
New York State Department of Health, Albany, NY, USA.
Parasit Vectors. 2022 Jun 28;15(1):238. doi: 10.1186/s13071-022-05304-9.
The emergence of vector-borne pathogens in novel geographic areas is regulated by the migration of their arthropod vectors. Blacklegged ticks (Ixodes scapularis) and the pathogens they vector, including the causative agents of Lyme disease, babesiosis and anaplasmosis, continue to grow in their population sizes and to expand in geographic range. Migration of this vector over the previous decades has been implicated as the cause of the re-emergence of the most prevalent infectious diseases in North America.
We systematically collected ticks from across New York State (hereafter referred to as New York) from 2004 to 2017 as part of routine tick-borne pathogen surveillance in the state. This time frame corresponds with an increase in range and incidence of tick-borne diseases within New York. We randomly sampled ticks from this collection to explore the evolutionary history and population dynamics of I. scapularis. We sequenced the mitochondrial genomes of each tick to characterize their current and historical spatial genetic structure and population growth using phylogeographic methods.
We sequenced whole mitochondrial genomes from 277 ticks collected across New York between 2004 and 2017. We found evidence of population genetic structure at a broad geographic scale due to differences in the relative abundance, but not the composition, of haplotypes among sampled ticks. Ticks were often most closely related to ticks from the same and nearby collection sites. The data indicate that both short- and long-range migration events shape the population dynamics of blacklegged ticks in New York.
We detailed the population dynamics of the blacklegged tick (Ixodes scapularis) in New York during a time frame in which tick-borne diseases were increasing in range and incidence. Migration of ticks occurred at both coarse and fine scales in the recent past despite evidence of limits to gene flow. Past and current tick population dynamics have implications for further range expansion as habitat suitability for ticks changes due to global climate change. Analyses of mitochondrial genome sequencing data will expound upon previously identified drivers of tick presence and abundance as well as identify additional drivers. These data provide a foundation on which to generate testable hypotheses on the drivers of tick population dynamics occurring at finer scales.
新地理区域中媒介传播病原体的出现受其节肢动物媒介的迁移所调控。黑腿蜱（Ixodes scapularis）及其传播的病原体，包括莱姆病、巴贝虫病和无形体病的病原体，其种群数量持续增长并扩大地理范围。过去几十年中，这种媒介的迁移被认为是导致北美的最常见传染病重新出现的原因。
我们系统地收集了 2004 年至 2017 年期间纽约州（以下简称纽约）各地的蜱虫，作为该州常规蜱传病原体监测的一部分。这一时间范围与纽约蜱传疾病的范围和发病率的增加相对应。我们从该采集物中随机抽取蜱虫，以探索 I. scapularis 的进化历史和种群动态。我们对每个蜱虫的线粒体基因组进行测序，以使用系统地理学方法来描述它们当前和历史的空间遗传结构和种群增长。
我们对 2004 年至 2017 年期间在纽约收集的 277 只蜱虫的整个线粒体基因组进行了测序。我们在广泛的地理尺度上发现了种群遗传结构的证据，这是由于采样蜱虫中相对丰富度不同但组成不同的单倍型造成的。蜱虫通常与同一和附近采集点的蜱虫最密切相关。数据表明，短距离和长距离迁移事件都塑造了纽约黑腿蜱的种群动态。
我们详细描述了在蜱传疾病范围和发病率增加的时间框架内，纽约黑腿蜱的种群动态。尽管存在基因流动限制的证据，但过去和现在的蜱虫种群动态都发生了在粗尺度和细尺度上的迁移事件。由于全球气候变化导致适合蜱虫生存的栖息地发生变化，过去和现在的蜱虫种群动态对进一步的范围扩展具有重要意义。线粒体基因组测序数据分析将详细说明以前确定的蜱虫存在和丰度的驱动因素，并确定其他驱动因素。这些数据为在更细的尺度上生成关于蜱虫种群动态驱动因素的可检验假设提供了基础。
