bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.06.24.497348

Ectoparasitism in Polystomatidae (Neodermata, Monogenea): phylogenetic position and mitogenome of Sphyranura euryceae, a parasite of the Oklahoma salamander

Leeming, S.·Hahn, C.·Koblmueller, S.·McAllister, C.·Vanhove, M. P. M.·Kmentova, N.
View original source ↗Export metadata ↓

Abstract

BackgroundPolystomatidae represents a monogenean group whose representatives infect mainly (semi)-aquatic tetrapods. Sphyranuridae with its single genus (Sphyranura) exhibits ectoparasitism on salamander hosts and was traditionally considered a sister-group to Polystomatidae based on the presence of a well-developed opisthaptor yet was distinguished due to the presence of a single pair of haptoral suckers, as opposed to the three pairs present in polystomatids. However, more recent molecular work supported its inclusion within Polystomatidae, at an early diverging, yet unresolved, position in the clade of polystomatids that otherwise exhibit endoparasitism of batrachians. Resolving the position of Sphyranura in relation to Polystomatidae is a prerequisite for understanding the factors driving evolution and the shifts between ecto- and endoparasitism in Polystomatidae. MethodsVarious staining methods were used to morphologically characterise collected specimens of Sphyranura. The mitochondrial genome was assembled from WGS data. Based on a combination of nuclear (18S, 28S rRNA) and mitochondrial markers (cox1, 12S) we inferred the phylogeny of Polystomatidae using Bayesian inference and maximum likelihood methods. ResultsBased on morphological examination and comparison with type material, specimens of Sphyranura infecting Oklahoma salamander (Eurycea tynerensis) at Greathouse Spring, Arkansas (USA), were identified as S. euryceae, a new distributional record for the species. Along with an amended diagnosis of Sphyranura we provide the first molecular data for S. euryceae. Mitochondrial level comparison reveals instances of tRNA gene rearrangements in polystomatids. Our phylogeny identifies two clades within polystomatids infecting tetrapods, one infecting exclusively batrachians, the other mainly known from chelonians. Although not fully supported, Sphyranura appears as the earliest branching lineage within the former. ConclusionsWith Sphyranura nested within Polystomatidae, we consider Sphyranuridae invalid. Sphyranuras apparent early branching position indicates ectoparasitism is an ancestral trait with endoparasitism having evolved later in the Polbatrach clade. However, the reduced number of haptoral suckers in representatives of Sphyranura is a derived characteristic potentially resulting from paedomorphic evolution. Whilst there is an indication towards phylogenetic congruence of polystomatids and their batrachian hosts, the same was not true for polystomatid parasites of chelonians with evidence of multiple host switches. Furthermore, geographic distribution of hosts was not found to drive polystomatid phylogeny.

Explore related subjects

evolutionary biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Leeming, S., Hahn, C., Koblmueller, S., McAllister, C., Vanhove, M. P. M., Kmentova, N.. 2022-06-26. Ectoparasitism in Polystomatidae (Neodermata, Monogenea): phylogenetic position and mitogenome of Sphyranura euryceae, a parasite of the Oklahoma salamander. https://doi.org/10.1101/2022.06.24.497348

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Global homeostatic forces shape the composition of a hyperdiverse tropical insect fauna

Despite comprising the bulk of terrestrial biodiversity, we know surprisingly little about insect faunas, particularly in the tropics. Here, we characterize the insect fauna of Madagascar, a global biodiversity hotspot, based on extensive DNA metabarcoding of Malaise trap and leaf litter samples. We estimate that the fauna comprises at least 250,000 species, only 5% of which are currently recorded. The ecological and taxonomic composition is surprisingly similar to that of temperate forests. We show that this is likely caused by global homeostatic forces shaping net diversification rates after colonization of Madagascar rather than by the composition of colonizing lineages. Features differing from temperate forests include the dearth of parasitoids and richness of beetles. Understanding the forces shaping these patterns is key in sustainable management of tropical insect faunas.

evolutionary biology↗
bioRxiv2026

Do divergent mitochondrial backgrounds alter the fate of nuclear alleles during hybridization and admixture?

Hybridization brings together genetic variation from different populations or species into admixed genomes. As selection sorts this variation, the fate of each allele is determined by its fitness effect in the new hybrid genomic background. Because mitochondrial genes coevolve with the nuclear genome, they may be especially sensitive to foreign nuclear backgrounds, making them potential "hot-spots" for hybrid incompatibilities. Here, we test whether selection against mitonuclear incompatibilities drives repeatable hybridization outcomes. Specifically, we experimentally evolved three sets of five populations of hybrid Drosophila melanogaster, each carrying the same nuclear chromosomes but paired with one of three increasingly divergent mitochondrial DNA backgrounds. We hypothesized that accumulated incompatibilities would result in different patterns of nuclear admixture among mitochondrial backgrounds. To test this, we tracked nuclear allele frequencies in all 15 populations by whole-genome sequencing at intermediate time points. After 25 generations, we observed that rapid genomic evolution produced a strikingly parallel mosaic of both nuclear ancestries, independent of mitochondrial background. Contrary to our hypothesis, we found no evidence that mitochondrial background1 shaped nuclear admixture, even for interspecific combinations. These results suggest that in species with large effective population sizes, efficient purifying selection limits the accumulation of mitonuclear incompatibilities, allowing selection on nuclear alleles to promote repeatable ancestry sorting immediately following hybridization.

evolutionary biology↗
bioRxiv2026

Body size cascades from Neodiprion sawfly hosts to Perilampid parasitoids: An investigation of sequential divergence

Ecological speciation drives diversity in plant-eating insect systems, but it may also generate parallel specialization in parasitoid associates in a cascading effect of "sequential divergence." However, sequential divergence has never been successfully identified in parasitoids of externally feeding insects. To address this gap, we consider the Pinus-Neodiprion-Perilampus neodiprioni system, where plant-associated, externally feeding Neodiprion demonstrate ecological divergence, as supported by body size as a magic trait in sympatric species. It seems possible that this body size differentiation may cascade to Neodiprion's parasitoids via sequential divergence. Therefore, we asked, "Does P. neodiprioni exhibit host-specific divergence in body size that parallels patterns in Neodiprion hosts?" Further, "Does P. neodiprioni exhibit host-related variation in the abdominal region or sexually dimorphic features, supporting reproductive barriers?" Using by-catch samples, we measured body size of P. neodiprioni, reared from Neodiprion lecontei and Neodiprion pinetum hosts. We analyzed body size variation as predicted by host species, parasitoid sex, host sex, host cocoon size, latitude, and their interactions. In addition, we used mixed models to analyze the effects of parasitoid sex and Neodiprion host on three size-based facial features. We found that P. neodiprioni demonstrates host-associated body size variation that mirrors size differences in their Neodiprion hosts. In addition, host-associated size variation occurs in the abdominal region and two sexually dimorphic characters of P. neodiprioni, supporting possible reproductive isolation. Together, these patterns suggest that host magic traits may drive not only within-species ecological divergence, but they can facilitate parasitoids' subsequent morphological differentiation and possible sequential divergence.

evolutionary biology↗