Evaluating food web interactions among microcrustaceans and insect in a tropical shallow lake using DNA-based protocol

Abstract

We developed species-specific primers of five microcrustacean preys, Ceriodaphnia richardi, Diaphanosoma cf. brevireme, Daphnia gessneri, Simocephalus serrulatus, Thermocyclops decipiens and Mesocyclops sp., to analyze food-web interactions involving their two insect predators Rheumatobates crassifemur and Martarega uruguayensis distributed in a tropical shallow lake. We designed internal primers of the COI gene (177–282 bp), and tested them, by means of PCR, for specificity and sensitivity. In our tests for specificity, all primers successfully amplified the DNA target but were species-specific failing to amplify the biomarker from any of the other species tested, even in a mixed DNA sample, including predators’ DNA. In tests for sensitivity, primers successfully amplified zooplankton biomarkers from low concentration of DNA extractions and also from digestive tract of predators, even after many hours of ingestion. This technique provides a framework as an efficient tool for evaluation of food-web research in natural aquatic environments, where it is impossible to observe if predation occurs. Furthermore, this technique provides an effective solution for the identification of zooplankton species from the predator’s digestive tract, where morphological identification alone is sometimes difficult because predators do not consume the prey but feeds using extra-oral digestion, such is the case of heteropterans.

Keywords:

• Barcoding gene
• COI
• food web
• gut content analysis
• zooplankton

Acknowledgments

We are also grateful to Alan L. Melo (Universidade Federal de Minas Gerais) for identifying the heteropterans, to Lourdes M.A. El-Moor Loureiro (Universidade Católica de Brasilia) for identifying the cladocerans and to Carlos E.F. da Rocha (Universidade de São Paulo) for identifying the copepods. We also thank anonymous reviewer for help with corrections and suggestions.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Additional information

Funding

This study is part of a PhD project of ARD under support of a scholarship from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES. Molecular and laboratory support for this study was provided by research grants from Fundação de Amparo a Pesquisa do Estado de São Paulo – FAPESP (Temáticos Biota 2010/50188-8 and INTERCRUSTA 2018/13685-5) and CAPES (Ciências do Mar II Proc. 2005/2014 − 23038.004308/2014-14) under FLM responsibility and coordination. FLM thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq for research fellowships (Proc. 304968/2014-5 and 302253/2019-0) for additional support. A-CB thanks CAPES for PhD scholarship. RR thanks FAPESP (2013/05663-8) and CAPES (Ciências do Mar II Proc. 2005/2014 − 23038.004308/2014-14) for post-doctoral scholarships.