Although parasite community studies are growing in numbers, our understanding of which macro-ecological and evolutionary processes have shaped parasite communities is still based on a narrow range of host–parasite systems. The present study assessed the diversity and endoparasite species composition in New Zealand deep-sea fish (grenadiers, family Macrouridae), and tested the effects of host phylogeny and geography on the structure of endoparasite communities using a distance decay framework. We found that grenadiers from the Chatham Rise harboured a surprisingly high diversity of digeneans, cestodes and nematodes, with different species of grenadiers having different parasite assemblages. Our results demonstrate that community similarity based on the presence/absence of parasites was only affected by the phylogenetic relatedness among grenadier species. In contrast, both phylogenetic distance among grenadiers (measured as the number of base-pair differences of DNA sequences) and geographic distance between sample locations influenced the similarity of parasite communities based on the parasites' prevalence and mean abundance. Our key findings highlight the significant effect of deep-sea host phylogeny in shaping their parasite assemblages, a factor previously neglected in studies of parasite communities in deep-sea systems.

There is great heterogeneity in parasite communities among hosts, understanding the nature and drivers of such variations is still a great scientific quest. Here, we analyse the variation in parasite communities by addressing the following questions: (i) What is the beta-diversity component (nestedness or turnover) that most contributes to beta diversity in parasite communities among anuran species? (ii) Does the beta diversity of parasite communities follow a non-random pattern? (iii) Is the dissimilarity in composition of parasite communities related to the phylogenetic or functional dissimilarity among hosts? We found that turnover in parasite assemblages was the main component of beta diversity, but the variation observed both in the total beta diversity and in its components did not differ from the respective null models. The dissimilarity among parasite communities was not related to the phylogenetic species variability or functional dissimilarity among anuran species for most localities. In short, our findings may indicate a process of resource tracking by the parasite species, in which the resource may not necessarily be conserved phylogenetically in their hosts.

We compared helminth communities in spiny mice (Acomys dimidiatus) from 4 wadis in the arid montane region of the southern Sinai in Egypt, in a 4-week period in late summer. Total helminth species richness was 14 (8 nematodes, 5 cestodes and 1 acanthocephalan) with 94% of mice carrying at least 1 species and an overall mean species richness of 1·85. The most prevalent parasites were Protospirura muricola (47·8%) and Dentostomella kuntzi (46·3%). One larval cestode, Joyeuxiella rossicum, represents a new host record. The helminth community was dominated by intestinal nematodes (88·7%) of which 58·2% were arthropod-transmitted heteroxenic species. At the component community level, 70% of the worms were recovered from mice in just two wadis (Gharaba and Tlah) and 48·6% of intestinal nematodes were from Wadi Gharaba. Although only 7 species of helminths were recorded from Wadi Gharaba, this site gave the highest Berger-Parker dominance index because of P. muricola. P. muricola was also dominant in Wadi El Arbaein whilst Syphacia minuta was the dominant species in Wadis Gebal and Tlah. At the infracommunity level, mean species richness and Brillouin's index of diversity were highest in Wadi Tlah and lowest in Wadi Gebal, and the former was age dependent. Whilst mice from different wadis differed in the nematodes that were most common, those from Wadi Gharaba carried the highest mean number of worms/mouse. The abundance of P. muricola in particular varied markedly between sites: Wadi Gharaba was distinct as the site showing the highest mean worm burden whereas mice from Wadi Gebal were uninfected. None of the directly transmitted oxyuroid nematodes showed significant variation in abundance between wadis, or host sex or age classes. Overall, the single extrinsic factor in the study, site of capture, was more important than the intrinsic factors in explaining variation in helminth communities in the region. We conclude that in the high mountains of southern Sinai, each wadi is distinct in terms of its rodent parasites, and hence we expect spatially different coevolutionary pressures on their hosts, with resultant variation in life-histories.