Host-Parasite Incongruences in Rodent Eimeria Suggest Significant Role of Adaptation Rather than Cophylogeny in Maintenance of Host Specificity

Abstract

The degree of host specificity, its phylogenetic conservativeness and origin are virtually unknown in Eimeria. This situation is largely due to the inadequate sample of eimerian molecular data available for reliable phylogenetic analyses. In this study, we extend the data set by adding 71 new sequences of coccidia infecting 16 small-mammal genera, mostly rodents. According to the respective feasibility of PCR gene amplification, the new samples are represented by one or more of the following genes: nuclear 18S rRNA, plastid ORF 470, and mitochondrial COI. Phylogenetic analyses of these sequences confirm the previous hypothesis that Eimeria, in its current morphology-based delimitation, is not a monophyletic group. Several samples of coccidia corresponding morphologically to other genera are scattered among the Eimeria lineages. More importantly, the distribution of eimerians from different hosts indicates that the clustering of eimerian species is influenced by their host specificity, but does not arise from a cophylogenetic/cospeciation process; while several clusters are specific to a particular host group, inner topologies within these clusters do not reflect host phylogeny. This observation suggests that the host specificity of Eimeria is caused by adaptive rather than cophylogenetic processes.

Diversity and host specificity of coccidia (Apicomplexa: Eimeriidae) in native and introduced squirrel species

“…As already mentioned, morphological identification of oocysts is often unreliable and, despite Eimeria spp. having usually a high host-specificity, a few studies gave evidence for the sharing of some species between different squirrel species (Levine and Ivens 1965;Motriuk-Smith et al 2009 Phylogenetic analyses of morphotype E2 (detected in both hosts) were based on 3 different markers (18S, ITS, cox I) as suggested by recent studies, which have described the use of multiple genetic markers in Eimeria species as an helpful tool to identify species boundaries or cryptic species (Kvičerová and Hypša 2013;Motriuk -Smith et al 2009Ogedengbe et al 2011). These analysis displayed fairly distinct monophyletic clades from each different host species isolates, with pairwise distance values for 18S (97.2-100%), and cox I (94.1-100%) datasets, which proved indisputable distinction between E2 morphotypes in red and grey squirrels.…”

“…Techniques of molecular taxonomy are helpful tool with better taxonomic resolution on species level in eimeriid coccidia using various markers (Kvičerová and Hypša 2013;Motriuk -Smith et al 2009Ogedengbe et al 2011). The 18S rDNA is broadly used for phylogenetic analyses within the genus Eimeria, facilitated by growing number of available sequences.…”

“…DNA was extracted from ~ 200 mg of sediment of representative samples using the PowerSoil DNA Isolation Kit (MO BIO Laboratories, Carlsbad, CA USA) according to the manufacturer's instructions. Three different markers, namely part of nuclear 18S rRNA, ITS region of nuclear rRNA = internal Kvičerová and Hypša (2013). The PCR reaction was performed in a 25 µl volume containing 2 µl (1-10 ng) of total DNA, 12.5 µl of commercial premix PPP master mix (Top-Bio s.r.o), 1 µl (400 µM) of each primer and 8.5 µl PCR H2O.…”

Check list of parasites and bacteria recorded from pangolins (Manis sp.)

“…Parasites reported from pangolins were identified to their species level in most of the cases, except eight cases where they were identified to their genus level. There were reports of six new parasite species described from pangolins, including two protozoan parasites (Eimeria tenggilingi and Eimeria nkaka), three helminth parasites (Dipetalonema fausti, Leipernema leiperi, Prolospirura hamospiculala) and one mite species (Manisicola africana) (Else and colley 1976;Kvicerova and Hypsa 2013;Esslinger 1966;Singh 1976;Neveu-Lemaire 1927;Lawrence 1939). It appears that the present checklist is the first comprehensive review of parasites and bacteria of pangolins.…”

Genomics of Apicomplexa

“…Eimeria parasites exhibit immense diversity in host range including mammals, birds, reptiles, fish and amphibians [81][82][83][84][85][86]. It is estimated that there are many thousands of Eimeria species [87].…”