Cryptic speciation and patterns of phenotypic variation of a highly variable acanthocephalan parasite

Abstract

An investigation of a parasite species that is broadly host- and habitat-specific and exhibits alternative transmission strategies was undertaken to examine intraspecific variability and if it can be attributed to cryptic speciation or environmentally induced plasticity. Specimens of an acanthocephalan parasite, Leptorhynchoides thecatus, collected throughout North America were analysed phylogenetically using sequences of the cytochrome oxidase I gene and the internal transcribed spacer region. Variation in host use, habitat use, and transmission were examined in a phylogenetic context to determine if they were more likely phylogenetically based or due to environmental influences. Results indicated that most of the variation detected can be explained by the presence of cryptic species. The majority of these species have narrow host and microhabitat specificities although one species, which also may comprise a complex of species, exhibits broad host and habitat specificity. Alternate transmission pathways only occurred in two of the cryptic species and correlate with host use patterns. Taxa that mature in piscivorous piscine hosts use a paratenic fish host to bridge the trophic gap between their amphipod intermediate host and piscivorous definitive host. One potential example of environmentally induced variation was identified in three populations of these parasites, which differ on their abilities to infect different host species.

Genetic and morphological diversity of Trisetacus species (Eriophyoidea: Phytoptidae) associated with coniferous trees in Poland: phylogeny, barcoding, host and habitat specialization

“…Host- and habitat-induced specialization is very common in parasitic and phytophagous taxa, e.g. avian feather lice (Johnson et al 2012), malaria parasites (Loiseau et al 2012), parasitic flatworms (Brooks and McLennan 1993), an acanthocephalan parasite (Steinauer et al 2007), fleas (Arbiv et al 2012), beetles (Blair et al 2005), parasitoid wasps (Kankare et al 2005), many phytophagous insects (Stireman et al 2005), and other eriophyoid mites (Miller et al 2013). …”

“…Variability in host or habitat use in parasites or herbivores has often been explained by the presence of cryptic species that exhibit narrower microhabitat preference or host range (e.g. Hebert et al 2004; Steinauer et al 2007; Johnson et al 2012). Microhabitat and host specificity have been proposed to play a large role in the speciation of organisms because specialization promotes speciation by reducing gene flow (Futuyma and Moreno 1988; Brooks and McLennan 1993).…”

Diversity and significance of eriophyoid mites (Acari: Eriophyoidea) associated with coniferous trees in Poland: a review

“…Such microhabitat and host specialization may play a large role in speciation because specialization may lead to reduced gene flow between populations associated with a specific host or microhabitat (futuyMa & Moreno 1988;BrookS & McLennan 1993;heBert et al 2004;Steinauer et al 2007). Host and habitat associations resulting in genetic and morphological differentiation (potentially leading to the formation of reproductive barriers) have also been observed in conifer-associated eriophyoid mites in Poland.…”

Proboscis profiler: a tool for detecting acanthocephalan morphotypes

“…However, the true species diversity in this phylum is masked by the phenomenon of cryptic speciation. Molecular systematics have suggested that each of the following taxa are complexes of two or more reproductively isolated, sibling species: Acanthocephaloides propinquus (Dujardin, 1845) Meyer, 1932 (see Buron et al, 1986), Echinorhynchus gadi Zoega in Müller, 1776 (see Väinölä et al, 1994), E. bothniensis Zdzitowiecki & Valtonen, 1987(see Väinölä et al, 1994, Leptorhynchoides thecatus (Linton, 1891) Kostylew, 1924 (see Steinauer et al, 2007) and Neoechinorhynchus golvani Salgado-Maldonado, 1978 (see Martínez-Aquino et al, 2009). Once dissected by molecular markers, the members of these species complexes are sometimes found to be distinguished by subtle morphometric differences (Buron et al, 1986;Wayland et al, 2005).…”

“…Consequently, this graphical approach has been proven to be effective in discriminating closely related species with different host-specificities and/ or allopatric distributions, since a meristogram can be generated for each host and/or geographical locality and the patterns compared (Huffman & Bullock, 1975;Huffman & Nickol, 1978). However, morphologically cryptic sibling species sometimes co-infect the same definitive host species (Steinauer et al, 2007) and even the same host individual (Wayland et al, 2005). In this situation, the worms would need to be grouped by biological species, inferred from molecular markers, before a meaningful meristogram analysis could be performed.…”