Niche modelling and molecular phylogenetics unravel the colonisation biology of three species of the freshwater planarian genus Girardia (Platyhelminthes, Tricladida)

Benítez-Álvarez, Lisandra; Leria, Laia; Sluys, Ronald; Leal-Zanchet, Ana María; Riutort, Marta

doi:10.1007/s10750-023-05239-x

Cited by 3 publications

References 65 publications

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A comparative analysis of planarian regeneration specificity reveals tissue polarity contributions of the axial cWnt signalling gradient

Cleland,

Vu,

Dickmann

et al. 2024

Preprint

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SummaryPlanarians exhibit remarkable whole-body regeneration abilities. The formation of heads at forward-facing wounds and tails at rearward-facing wounds suggests an intrinsic tissue polarity guiding regeneration. While the underlying mechanisms remain unclear, reports of double-headed regenerates from increasingly narrow tissue fragments have long been hypothesised to reflect gradient-based polarity specification. Here, we systematically re-examine this hypothesis in the modern model speciesSchmidtea mediterraneaand a representative of the genus likely used in the original studies,Girardia sinensis. While we never observed double-heads inS. mediterranea,G. sinensisreadily regenerated double-heads in a manner dependent on piece length, anatomical position and body size. We found that the reduced regeneration robustness ofG. sinensiswas partially explained by wound site-symmetric expression of the head determinantnotum, which is highly anterior-specific inS. mediterranea. Exploring what else might mediate head/tail regeneration specificity inG. sinensis, we examined the role of the conserved tail-to-head cWnt signalling gradient. By developing a time-resolved pharmacological approach to reduce the cWnt gradient slope without affecting wound-induced cWnt signalling dynamics, we observed an increased incidence of double-headed regenerates. In addition, the body size-dependence of double-head formation correlated with the decreasing steepness of the cWnt gradient due to scaling. Taken together, our results indicate that the slope of the cWnt gradient may contribute to planarian head/tail regeneration specificity. Furthermore, they suggest that planarian tissue polarity is composed of multiple parallely-acting polarity cues, the differential reliance on which contributes to the observed interspecies variation in regeneration specificity.

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A comparative analysis of planarian regeneration specificity reveals tissue polarity contributions of the axial cWnt signalling gradient

Cleland,

Vu,

Dickmann

et al. 2024

Preprint

View full text Add to dashboard Cite

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Treasure island: DNA data reveals unknown diversity in Cuban freshwater planarians (Platyhelminthes: Tricladida)

Catalá,

Benítez-Álvarez,

Diez

et al. 2024

Zoologia (Curitiba)

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Little neighbours in Hamburg: free-living aquatic flatworms (Platyhelminthes)

Diez,

Schmidt-Rhaesa

2024

EvolSyst

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Free-living flatworms, also known as turbellarians, are abundant and key components of aquatic habitats. They play vital roles in food webs and contribute to ecosystem health. However, our understanding of their diversity remains limited, even from comparably well-studied regions of Europe. In this work, we summarise the available records on aquatic turbellarians from Hamburg, Germany, provide new records based on material obtained during exploratory collecting, and place selected species in a molecular phylogenetic context. We sampled four localities in Hamburg, two urban and two suburban, and three other localities in Germany and Switzerland, collecting submerged vegetation, litter, and mosses. Prior to our investigation, Hamburg had documented 26 species of aquatic turbellarians. Our collections have led to the first recorded instances of Stenostomum gotlandense and Castrella alba in Germany, along with four new species for Hamburg: Macrostomum rostratum, Microdalyellia schmidtii, Krumbachia hiemalis, and Polycelis tenuis. Additionally, we provide updated information for five species previously recorded from Hamburg: S. leucops, Prorhynchus stagnalis, Microdalyellia armigera, Gyratrix hermaphroditus, and Planaria torva. The phylogenetic analysis revealed cryptic diversity within S. grande and S. leucops, with S. grande comprising two distinct clades (Brazil and Japan + Germany), and S. leucops consisting of four clades (Sweden + Germany, two from Finland, and Brazil). One of the Finnish clades, S. leucops aquariorum, is both morphologically and molecularly distinct, and we recognise it as a valid species, now S. aquariorum. Future research is needed to further clarify the relationships of the remaining clades of these two species, particularly with material from their type localities in the United States. Among rhabdocoel microturbellarians, we identified cryptic diversity within Castrella truncata (with European and North American lineages) and Microdalyellia armigera (encompassing Finnish and Spanish lineages). We also provided the first molecular evidence supporting the monophyly of Krumbachia following the sequencing of K. hiemalis. Conversely, species of Bothromesostoma were found to be nested within a clade containing species of Mesostoma, leading us to propose synonymising these genera. Overall, our study underscores the rich biodiversity potential of urban and suburban ecosystems for detecting freshwater turbellarian species, while highlighting the need for further research in Hamburg and across Germany to clarify species distributions. Moreover, molecular phylogenetic analyses have uncovered cryptic diversity in several species of catenulids and rhabdocoels, emphasizing the importance of future efforts to describe potential new species.

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Niche modelling and molecular phylogenetics unravel the colonisation biology of three species of the freshwater planarian genus Girardia (Platyhelminthes, Tricladida)

Cited by 3 publications

References 65 publications

A comparative analysis of planarian regeneration specificity reveals tissue polarity contributions of the axial cWnt signalling gradient

A comparative analysis of planarian regeneration specificity reveals tissue polarity contributions of the axial cWnt signalling gradient

Treasure island: DNA data reveals unknown diversity in Cuban freshwater planarians (Platyhelminthes: Tricladida)

Little neighbours in Hamburg: free-living aquatic flatworms (Platyhelminthes)

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