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Research Article

Molecular markers and SEM imaging reveal pseudocryptic diversity within the Ponto-Caspian low-profile amphipod invader Dikerogammarus bispinosus

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Pages 94-108 | Received 03 Aug 2021, Accepted 08 Dec 2021, Published online: 03 Feb 2022

Figures & data

Table I. Localities and GenBank accession numbers of specimens used for the current study. N – 54

Figure 1. Phylogenetic relationships of Dikerogammarus species based on maximum-likelihood gene trees (left) and haplotype networks (right) of the COI and 28S fragments. Numbers above tree branches represent statistical support (ultrafast bootstrap and Shimodaira-Hasegawa approximate likelihood ratio test). Colored boxes next to the trees indicate the results of the species delimitation analyses. Numbers within the mPTP column are posterior probabilities for species support.

Figure 1. Phylogenetic relationships of Dikerogammarus species based on maximum-likelihood gene trees (left) and haplotype networks (right) of the COI and 28S fragments. Numbers above tree branches represent statistical support (ultrafast bootstrap and Shimodaira-Hasegawa approximate likelihood ratio test). Colored boxes next to the trees indicate the results of the species delimitation analyses. Numbers within the mPTP column are posterior probabilities for species support.

Figure 2. Phylogeny of Dikerogammarus based on a combined COI and 28S dataset. Left, time-calibrated Bayesian species tree. Numbers above branches are posterior probabilities. Right, maximum-likelihood tree based on locus concatenation. Numbers above branches represent statistical support from ultrafast bootstrap and the Shimodaira-Hasegawa approximate likelihood ratio test.

Figure 2. Phylogeny of Dikerogammarus based on a combined COI and 28S dataset. Left, time-calibrated Bayesian species tree. Numbers above branches are posterior probabilities. Right, maximum-likelihood tree based on locus concatenation. Numbers above branches represent statistical support from ultrafast bootstrap and the Shimodaira-Hasegawa approximate likelihood ratio test.

Table II. Results of Bayes factor species delimitation (BFD) based on Bayesian multilocus analysis of COI and 28S fragments

Figure 3. Distribution of D. bispinosus MOTUs: D. bispinosus 1 – red; D. bispinosus 2 – yellow; D. bispinosus 3 – blue.

Figure 3. Distribution of D. bispinosus MOTUs: D. bispinosus 1 – red; D. bispinosus 2 – yellow; D. bispinosus 3 – blue.

Table III. Estimates of evolutionary divergence between groups (mean p-distances) based on COI gene region (below diagonal) and 28S (above diagonal)

Figure 4. SEM pictures of antenna 2 and gnathopod 2 from D. bispinosus 1 (A, B), D. bispinosus 2 (C, D) and D. bispinosus 3 (E, F) respectively.

Figure 4. SEM pictures of antenna 2 and gnathopod 2 from D. bispinosus 1 (A, B), D. bispinosus 2 (C, D) and D. bispinosus 3 (E, F) respectively.