A fine-scale phylogenetic assessment of digenean trematodes in central Alberta reveals we have yet to uncover their total diversity - PubMed (original) (raw)

. 2019 Feb 28;9(6):3153-3238.

doi: 10.1002/ece3.4939. eCollection 2019 Mar.

Affiliations

A fine-scale phylogenetic assessment of digenean trematodes in central Alberta reveals we have yet to uncover their total diversity

Michelle A Gordy et al. Ecol Evol. 2019.

Abstract

Despite over 100 years of digenean trematode parasite species descriptions, from a wide diversity of vertebrate and invertebrate host species, our ability to recognize the diversity of trematode species within a single lake remains an incredible challenge. The most challenging aspect is the identification of species from larval stages derived from intermediate hosts, due to the disjointed data of adult worm morphological descriptions, from which species are named, and links to corresponding molecular identifiers in depauperate databases. Cryptic species also play a significant role in the challenge of linking trematode larvae to adults, species identifications, and estimating diversity. Herein, we utilize a large, longitudinal dataset of snail first-intermediate host infection data from lakes in Alberta, Canada, to infer trematode larval diversity using molecular phylogenetics and snail host associations. From our assessments, we uncover a diversity of 79 larval trematode species among just five snail host species. Only 14 species were identified to a previously described species, while the other 65 species are either cryptic or otherwise unrepresented by mitochondrial genes in GenBank. This study currently represents the largest and most diverse singular molecular survey of trematode larval fauna composed of over one thousand mitochondrial sequences. Surprisingly, rarefaction analyses indicate we have yet to capture the complete diversity of trematodes from our sampling area.

Keywords: Alberta; cercariae; digenea; diversity; phylogenetics; trematoda.

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Conflict of interest statement

None declared.

Figures

Figure 1

Figure 1

Sample collection locations. Map of the six lakes from which snails and trematodes were collected in central Alberta, Canada. Depth of lake is given as a mean depth in meters

Figure 2

Figure 2

Molecular phylogeny of the Notocotylidae and Psilostomidae based on cox1. Bayesian inference phylogenies are given. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 are reported near the nodes, respectively. Accession numbers are given after species names. Emboldened taxa with three asterisks represent novel species from molecular analyses. (a) Notocotylidae. (b) Psilostomidae

Figure 3

Figure 3

Molecular phylogeny of the Haematoloechidae and Plagiorchiidae based on cox1. Bayesian inference phylogenies are given. Clades representing a single species have been condensed for space. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 are reported near the nodes, respectively. Accession numbers are given after species names. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. Emboldened taxa with three asterisks represent novel species from molecular analyses. (a) Haematoloechidae. (b) Plagiorchiidae

Figure 4

Figure 4

Molecular phylogeny of the Echinostomatidae: Drepanocephalus and Neopetasiger genera based on nad1. Bayesian inference phylogenies are given. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 from BI and ML analyses are reported near the nodes, respectively. Accession numbers are given after species names. Clades representing a single species have been condensed for space. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. (a) Drepanocephalus. (b) Neopetasiger

Figure 5

Figure 5

Molecular phylogeny of the Echinostomatidae: Echinoparyphium/Hypoderaeum genera based on nad1 and cox1. Bayesian inference phylogenies are given. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 from BI and ML analyses are reported near the nodes, respectively. Accession numbers are given after species names. Clades representing a single species have been condensed for space. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. Emboldened taxa with three asterisks represent novel species from molecular analysis. (a) nad1. (b) cox1

Figure 6

Figure 6

Molecular phylogeny of the Echinostomatidae based on nad1. Bayesian inference phylogenies are given. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 from BI and ML analyses are reported near the nodes, respectively. Accession numbers are given after species names. Clades representing a single species have been condensed for space. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study

Figure 7

Figure 7

Molecular phylogenies of the Diplostomidae‐I Group based on cox1. Clades representing a single species have been condensed for space. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Bootstrap values >50 and posterior probabilities >0.50 are reported near the nodes. Numbers in brackets after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. Emboldened taxa with three asterisks represent novel species from molecular analyses. (a) Maximum‐likelihood tree. (b) Bayesian inference tree

Figure 8

Figure 8

Molecular phylogenies of the Diplostomidae‐II Group based on cox1. Clades representing a single species have been condensed for space. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Bootstrap values >50 and posterior probabilities >0.50 are reported near the nodes. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. Emboldened taxa with three asterisks represent novel species from molecular analyses. Black diamonds represent sequences identified uniquely in GenBank that have high similarity and likelihood of being the same as a different species. (a) Maximum‐likelihood tree. (b) Bayesian inference tree

Figure 9

Figure 9

Molecular phylogenies of the Strigeidae based on cox1. Bayesian inference phylogenies are given. Clades representing a single species have been condensed for space. Branches are colored by support values from phylogenetic analyses, with blue having the highest support. Posterior probabilities >0.50 and bootstrap values >50 are reported near the nodes, respectively. Accession numbers are given after species names. Numbers in parentheses after taxon names correspond to the number of sequences within the clade. The first number is number of GenBank sequences and the second number, if given, represents number of sequences from this study. Emboldened taxa with three asterisks represent novel species from molecular analyses. (a) Strigeidae‐I. (b) Strigeidae‐II

Figure 10

Figure 10

Species accumulation. Several methods confirm that if delineation confidence for species differences is based on morphological identification, a plateau is reached for the maximum number of species within the study area. Whereas if confidence is based on molecular phylogenetic methods, we have yet to attain the true diversity of trematode species within the study area. (a) Collector method for accumulating sites as in the dataset, (b) Rarefaction for number of individuals, (c) Random method for accumulating sites given as a boxplot, with nonlinear Arrhenius model results displayed as lines behind the boxplot, (d) Rarefaction for number of individuals by snail species, (e) Random method for accumulating sites given as a boxplot for snail species

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