Diagne Christophe, Granjon Laurent, Tatard Caroline, Ribas Alexis, Ndiaye Arame, Kane Mamadou, Niang Youssoupha, Brouat Carine
CBGP, IRD, CIRAD, INRAE, Montpellier SupAgro, Univ. Montpellier, Montferrier-sur-Lez, France.
Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique Evolution, Orsay, France.
Front Vet Sci. 2021 Oct 26;8:740617. doi: 10.3389/fvets.2021.740617. eCollection 2021.
Previous field-based studies have evidenced patterns in gastrointestinal helminth (GIH) assemblages of rodent communities that are consistent with "enemy release" and "spill-back" hypotheses, suggesting a role of parasites in the ongoing invasion success of the exotic house mouse () in Senegal (West Africa). However, these findings came from a single invasion route, thus preventing to ascertain that they did not result from stochastic and/or selective processes that could differ across invasion pathways. In the present study, we investigated the distribution of rodent communities and their GIH assemblages in three distinct zones of Northern Senegal, which corresponded to independent house mouse invasion fronts. Our findings first showed an unexpectedly rapid spread of the house mouse, which reached even remote areas where native species would have been expected to dominate the rodent communities. They also strengthened previous insights suggesting a role of helminths in the invasion success of the house mouse, such as: (i) low infestation rates of invading mice by the exotic nematode at invasion fronts-except in a single zone where the establishment of the house mouse could be older than initially thought, which was consistent with the "enemy release" hypothesis; and (ii) higher infection rates by the local cestode in native rodents with long co-existence history with invasive mice, bringing support to the "spill-back" hypothesis. Therefore, "enemy release" and "spill-back" mechanisms should be seriously considered when explaining the invasion success of the house mouse-provided further experimental works demonstrate that involved GIHs affect rodent fitness or exert selective pressures. Next steps should also include evolutionary, immunological, and behavioral perspectives to fully capture the complexity, causes and consequences of GIH variations along these invasion routes.
先前的实地研究已经证明，啮齿动物群落的胃肠道蠕虫（GIH）组合模式与“天敌释放”和“溢出”假说一致，这表明寄生虫在塞内加尔（西非）外来家鼠（）的持续入侵成功中发挥了作用。然而，这些发现来自单一的入侵路径，因此无法确定它们不是由不同入侵途径中可能不同的随机和/或选择过程导致的。在本研究中，我们调查了塞内加尔北部三个不同区域的啮齿动物群落及其GIH组合的分布，这些区域对应于独立的家鼠入侵前沿。我们的研究结果首先表明，家鼠的传播速度出乎意料地快，甚至到达了预计本地物种会在啮齿动物群落中占主导地位的偏远地区。它们还强化了先前的见解，表明蠕虫在家鼠入侵成功中发挥了作用，例如：（i）在入侵前沿，外来线虫对入侵小鼠的感染率较低——除了一个家鼠定居时间可能比最初认为的更早的区域，这与“天敌释放”假说一致；（ii）在与入侵小鼠有长期共存历史的本地啮齿动物中，本地绦虫的感染率较高，这为“溢出”假说提供了支持。因此，在解释家鼠的入侵成功时，应认真考虑“天敌释放”和“溢出”机制——前提是进一步的实验工作表明所涉及的GIH会影响啮齿动物的适应性或施加选择压力。后续步骤还应包括从进化生物学、免疫学和行为学的角度，以全面了解这些入侵路径上GIH变化的复杂性、原因和后果。
