Abstracts (first author)
Between-host phylogenetic distance and performance of haematophagous ectoparasites
Parasites vary in their abundance among host species. The host used by the majority of parasite individuals is considered the principal host, while the remaining host species are referred to as auxiliary hosts. Variation in parasite abundance among auxiliary hosts reflects the degree of phylogenetic proximity between the principal host and the auxiliary hosts it used. The mechanism underlying this pattern is expected to be related to differential performance (feeding and reproductive) of parasites in auxiliary hosts that differ in their phylogenetic distance from the principal host. We tested this hypothesis using fleas parasitic on small mammals. Although feeding performance (blood meal size, energy expenditure for digestion and time of digestion) of parasites differed among different hosts, (1) they did not always perform better on a principal host than on an auxiliary host; and (2) their performance on an auxiliary host was not negatively correlated with phylogenetic distance of this host from the principal host. In accordance with our hypothesis, reproductive performance of parasites (egg and/or new imago production) in an auxiliary host decreased significantly with an increase in phylogenetic distance between an auxiliary and the principal host. However, this was true only for auxiliary hosts belonging to the same family as the principal host. One of the proximate causes for lower reproductive performance and subsequent lower abundance of parasites on auxiliary hosts appeared to be the higher energy cost of egg production in the latter. However, in some parasite species, lower offspring number in an auxiliary host was compensated to some extent by offspring size, although this compensation might also compromise parasites’ future reproduction via decreased survival. In other words, reproductive strategy implied during exploitation of low profitable (i.e., auxiliary) hosts may differ between parasite species.