Combining stable isotopes, morphological, and molecular analyses to reconstruct the diet of free‐ranging consumers

• Published in: Ecology and evolution 2020-07, Vol.10 (13), p.6664-6676
• Main Authors: Bonin, Michaël, Dussault, Christian, Taillon, Joëlle, Lecomte, Nicolas, Côté, Steeve D.
• Format: Article
• Language: English
• Subjects: Analytical methods; Animal behavior; Animals; Biomarkers; Canis lupus; Carnivores; Consumers; Deoxyribonucleic acid; Diet; diet reconstruction; DNA; Empirical analysis; Estimates; Feces; feeding strategies; Food; Food chains; Food sources; Food webs; Foraging behavior; Isotopes; Methods; molecular diet analyses; morphological diet analyses; Morphology; omnivores; Original Research; Population studies; Stable isotopes; Stomach; Studies; Taxonomy; trophic interactions; Ursus americanus
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6397

Accurate estimates of animal diet composition are essential to untangle complex interactions in food webs. Biomarkers and molecular tools are increasingly used to estimate diet, sometimes alongside traditional dietary tracing methods. Yet only a few empirical studies have compared the outcomes and potential gains of using a combination of these methods, especially using free‐ranging animals with distinct foraging preferences. We used stable isotopes, morphological, and molecular analyses to investigate the diet of free‐ranging consumers with two distinct diet types, that is, carnivore and omnivore. By combining the three analytical methods to assess the diet of consumers during the same period, we aimed to identify the limits of each method and to assess the potential benefits of their combined use to derive diet estimates. Our results showed that the different methods led to a consistent diet description for carnivores, which have a relatively simple diet mixture, but their outcomes somewhat differed for omnivore, which have a more complex diet. Still, the combined use of morphological and molecular analyses enhanced the diversity of food sources detected compared to the use of a single method independently of diet types. Precision of diet estimates derived from stable isotope analyses was improved by the addition of priors obtained from morphological and molecular diet analyses of the same population. Although we used free‐ranging animals without a known diet, our empirical testing of three of the most widely used methods of diet determination highlights the limits of relying over a single approach, especially in systems with few or no a priori information about the foraging habits of consumers. The choice of an appropriate approach of diet description should be a key step when planning dietary studies of free‐ranging populations. We recommend using more than one dietary determination methods especially for species with complex diet mixtures. Estimates of diet composition are essential to decipher complex interactions in food webs. Combining approaches of diet reconstruction gains in popularity as it could bring complementary information about consumers' food habits. Still, there are few empirical examples of the outcomes of different methods applied to a consumer diet over the same period. Here, we compared the use of stable isotopes, morphological, and molecular analyses over a same period to reconstruct the diet of free‐ranging consumers with distinct