Trait-Based Research on Rotifera: The Holy Grail or Just Messy?

Abstract

In recent years, trait-based research on plankton has gained interest because of its potential to uncover general roles in ecology. While trait categories for phytoplankton and crustaceans have been posited, rotifer trait assessment has lagged behind. Here, we reviewed the literature to assess traits key to their life histories and provided a data matrix for the 138 valid genera of phylum Rotifera. We considered seven traits: habitat type, trophi type, presence of lorica and foot, predation defense attributes, corona type, and feeding traits. While most traits were morphological attributes and supposedly easy to assess, we were faced with several challenges regarding trait assignment. Feeding traits were especially difficult to assess for many genera because relevant information was missing. Our assembled trait matrix provides a foundation that will initiate additional research on rotifer functional diversity, diminish the misclassification of rotifer genera into trait categories, and facilitate studies across trophic levels.

Diversity, Composition and Environmental Relations of Periphytic Rotifer Assemblages in Lentic Freshwater Bodies (Flanders, Lower Belgium)

“…Our combination of morphological, behavioural and physiological traits yielded nine functional groups, of which seven may be considered autochthonous for the periphyton and two as more or less planktonic. In comparison, Obertegger and Wallace [62] clustered all 138 rotifer genera into ten groups using a somewhat different trait selection (e.g., including corona type but not diet) and non-fuzzy coding. For the 54 genera in common, only one of their clusters matched entirely with one of our functional groups (cluster 1 and FG7, bdelloids).…”

“…Grouping of traits within these categories was not always clear-cut. Habitat specificity may be considered an overarching trait [62], which we classified here as behavioural. Likewise, size is also a key trait relating to a range of organismal properties, including behavioural and physiological features.…”

“…Next, the relation of assemblage composition and multi-trait functional-group representation to environmental conditions is examined in more detail. Combination of a taxonomic with a trait-based approach may provide a more complete understanding of ecological relations and ecosystem status, but multiple traits have been rarely considered for littoral meiofauna from lentic waterbodies, especially rotifers, so far [61][62][63]. Hence, their complementarity is largely left unexplored.…”

The dorsal plate is a critical feature in the reassessment of the rotiferan genus Ptygura (Monogononta; Gnesiotrocha; Flosculariidae)

“…While sessile Collothecaceae are all raptorial macrophages with uncinate trophi, Flosculariaceae are microphages filter feeders with malleoramate trophi (Obertegger & Wallace 2023). Currently nine genera of Flosculariidae are recognized: Beauchampia, Floscularia, Lacinularia, Lacinularoides, Limnias, Octotrocha, Pentatrocha, Ptygura, and Sinantherina (Meksuwan et al 2011).…”

Discordant spatiotemporal dynamics of functional and phylogenetic diversity of rotiferan communities exposed to aquaculture effluent

“…However, while the theoretical basis of species diversity, namely the species concept, is well established, the same cannot be said about functional diversity (Moretti et al, 2017). Nonetheless, over the last decade, the focus of diversity‐based analyses shifted from taxonomic to trait‐based approaches (Obertegger & Wallace, 2023). Using functional diversity constrains the possible parameter space (there are more species than species traits), but enables generalizations across communities and ecosystems that are needed to investigate the general consequences of the various changes—often due to anthropogenic stressors—for ecosystem processes (Hortal et al, 2015; Kunstler et al, 2016; McGill et al, 2006).…”