Using biological traits to assess diet selection: the case of the Pyrenean Desman

Traditionally, researchers have assessed diet selection by comparing consumed versus available taxa. However, taxonomic assignment is probably irrelevant for predators, who likely base their selection on characteristics including prey size, habitat, or behavior. Here, we use an aquatic insectivore,...

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Bibliographic Details
Published in:Journal of mammalogy 2023-12, Vol.104 (6), p.1205-1215
Main Authors: Esnaola, Amaiur, Larrañaga, Aitor, González-Esteban, Jorge, Elosegi, Arturo, Aihartza, Joxerra
Format: Article
Language:English
Subjects:
aquatic mammal
comportamiento trófico
DNA metabarcoding
endangered species
especie amenazada
feeding behavior
functional traits
macroinvertebrados
macroinvertebrates
mamífero acuático
rasgos funcionales
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Summary:Traditionally, researchers have assessed diet selection by comparing consumed versus available taxa. However, taxonomic assignment is probably irrelevant for predators, who likely base their selection on characteristics including prey size, habitat, or behavior. Here, we use an aquatic insectivore, the threatened Pyrenean Desman (Galemys pyrenaicus), as a model species to assess whether biological traits help unravel the criteria driving food and habitat preferences. We reanalyzed data from a previous taxonomy-based study of prey selection in two contrasting streams, one with excellent conservation status and the other affected by diversion for hydropower and forestry. Available and consumed prey were characterized according to nine biological traits, and diet selection was estimated by comparing availability—measured from Surber net samples, and consumption—analyzed by metabarcoding desman feces. Traits offered a biologically coherent image of diet and almost identical selection patterns in both streams, depicting a highly specialized rheophilic predator. Desmans positively selected prey with a preference for fast flow and boulder substrate, indicating their preferred riffle habitat. On the other hand, they positively selected prey with larger but not the largest potential size, living in the water column or the litter, and not inside sediments. They also chose agile prey, swimmers or prey attached to the substrate, prey with high body flexibility, and prey living exposed and clustered in groups. Overall, our results offer a picture of desman diet preference and point to biological traits as being better than taxonomic identity to describe the diet preference of consumers. Tradicionalmente, los investigadores han estimado la selección de dieta comparando los taxones ingeridos con los disponibles. Sin embargo, la asignación taxonómica probablemente sea irrelevante para los depredadores, que probablemente basan su selección en características tales como el tamaño de presa, su hábitat o su comportamiento. Aquí, utilizamos como especie modelo un insectívoro acuático, el amenazado desmán ibérico (Galemys pyrenaicus), para evaluar si los rasgos biológicos ayudan a desvelar los criterios que rigen las preferencias de alimentos y de hábitat. Reanalizamos los datos de un estudio previo basado en taxonomía sobre la selección de presas de desmán en dos ríos diferentes, uno en excelente estado de conservación y el otro afectado por la derivación de agua para producci
ISSN:0022-2372
1545-1542
DOI:10.1093/jmammal/gyad061