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.本研究针对两种蚤类物种（切氏细蚤（Parapulex chephrenis）、印度客蚤（Xenopsylla ramesis））的繁殖性能展开探究，两类蚤类分别寄生于一种主要宿主（principal host）或八种备选辅助宿主物种中的任意一种。我们提出如下研究假说：其一，相较于辅助宿主，蚤类寄生于主要宿主时可产出更多虫卵与成虫后代；其二，相较于与主要宿主系统发育距离（phylogenetic distance）较远的辅助宿主，蚤类寄生于与主要宿主亲缘关系较近的辅助宿主时繁殖表现更优。在两种蚤类中，单雌单次吸血后的虫卵生成量，以及在宿主身上持续栖息一段预设时长后新羽化成虫的产出量，均因宿主物种不同而存在显著差异。总体而言，除与主要宿主亲缘关系最近的辅助宿主外，寄生于其他辅助宿主的蚤类，其虫卵或新羽化成虫产出量均低于寄生于主要宿主的个体。当纳入所有辅助宿主物种进行分析时，我们未发现蚤类寄生于辅助宿主时的虫卵或新羽化成虫产出量，与该辅助宿主和主要宿主之间的系统发育距离存在显著相关性。然而，当分析范围限定为与主要宿主同科（鼠科Muridae）的辅助宿主时，寄生于此类辅助宿主的蚤类，其新羽化成虫产出量（切氏细蚤）或虫卵与新羽化成虫产出量（印度客蚤），随辅助宿主与主要宿主之间系统发育距离的增加而显著降低。本研究结果表明，寄生虫在两类辅助宿主中可获得更高的适合度（fitness）：一类是与主要宿主亲缘关系最近的辅助宿主，另一类则是与主要宿主亲缘关系最远的辅助宿主。这一发现或对入侵新区域的寄生虫的宿主关联模式产生影响。