Data from: Ectoparasite fitness in auxiliary hosts: Phylogenetic distance from a principal host matters

We studied reproductive performance in two flea species (Parapulex chephrenis and Xenopsylla ramesis) exploiting either a principal or one of eight auxiliary host species. We predicted that fleas would produce more eggs and adult offspring when exploiting (a) a principal host than an auxiliary host and (b) an auxiliary host phylogenetically close to a principal host than an auxiliary host phylogenetically distant from a principal host. In both flea species, egg production per female after one feeding and production of new imago after a timed period of an uninterrupted stay on a host differed significantly between host species. In general, egg and/or new imago production in fleas feeding on an auxiliary host was lower than in fleas feeding on the principal host, except for the auxiliary host that was the closest relative of the principal host. When all auxiliary host species were considered, we did not find any significant relationship between either egg or new imago production in fleas exploiting an auxiliary host and phylogenetic distance between this host and the principal host. However, when the analyses were restricted to auxiliary hosts belonging to the same family as the principal host (Muridae), new imago production (for P. chephrenis) or both egg and new imago production (for X. ramesis) in an auxiliary host decreased significantly with an increase in phylogenetic distance between the auxiliary and principal host. Our results demonstrated that a parasite achieves higher fitness in auxiliary hosts that are either the most closely-related to or the most distant from its principal host. This may affect host associations of a parasite invading new areas.

本研究针对两种跳蚤——具带量蚤（Parapulex chephrenis）与印度客蚤（Xenopsylla ramesis）展开，探究其分别寄居于主要宿主（principal host）或8种辅助宿主（auxiliary host）时的繁殖表现。我们提出两项研究假设：其一，跳蚤寄居于主要宿主时，单雌产卵量及成虫子代产出量均高于寄居于辅助宿主时；其二，跳蚤寄居于与主要宿主系统发育关系较近的辅助宿主时，繁殖产出高于寄居于与主要宿主系统发育关系较远的辅助宿主时。针对两种跳蚤而言，单次吸血后的单雌产卵量，以及在宿主身上持续停留指定时长后新生成虫的产出量，均因宿主种类不同而存在显著差异。总体而言，寄居于辅助宿主的跳蚤，其产卵量及/或新生成虫产出量均低于寄居于主要宿主的跳蚤，但与主要宿主亲缘关系最近的辅助宿主属于例外情况。当纳入所有辅助宿主物种进行整体分析时，未发现寄居于辅助宿主的跳蚤的产卵量或新生成虫产出量，与该辅助宿主同主要宿主之间的系统发育距离（phylogenetic distance）存在显著关联。然而，当分析仅限定于与主要宿主同科（鼠科Muridae）的辅助宿主时，随着辅助宿主与主要宿主的系统发育距离增大，寄居于该辅助宿主的跳蚤的新生成虫产出量（具带量蚤）或产卵量与新生成虫产出量（印度客蚤）均显著降低。本研究结果表明，寄生虫在与主要宿主亲缘关系极近或极远的辅助宿主中可获得更高的适合度（fitness），这一现象可能会影响入侵新区域的寄生虫的宿主关联模式。