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Investigating the ecology and evolution of cryptic marine nematode species through quantitative real‐time PCR of the ribosomal ITS region
Author(s) -
DERYCKE S.,
SHEIBANI TEZERJI R.,
RIGAUX A.,
MOENS T.
Publication year - 2012
Publication title -
molecular ecology resources
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.96
H-Index - 136
eISSN - 1755-0998
pISSN - 1755-098X
DOI - 10.1111/j.1755-0998.2012.03128.x
Subject(s) - biology , species complex , nematode , internal transcribed spacer , ecology , ribosomal dna , ribosomal rna , environmental dna , dna barcoding , evolutionary biology , zoology , phylogenetics , gene , biodiversity , genetics , phylogenetic tree
The presence of morphologically similar but genetically distinct species has impacted biogeographical and ecological paradigms. In marine sediments, free‐living nematodes form one of the most abundant and diverse faunal groups. Inferring the importance of nematode diversity for ecosystem functioning requires species‐level identification, which is hampered by the lack of easily observable diagnostic characters and the presence of cryptic species. New techniques are urgently needed to adequately study the ecology and evolution of cryptic species. The aim of the present study was to evaluate the potential of a quantitative real‐time PCR (qPCR) assay using the internal transcribed spacer (ITS) region of the ribosomal DNA to detect and quantify cryptic species of the R. (P.) marina complex. All primer pairs proved to be highly specific, and each primer pair was able to detect a single juvenile in a pool of 100 nematodes. C t values were significantly different between developmental stages for all species except for PmIII. Despite differences between developmental stages, a strong correlation was observed between the amount of extracted DNA and the number of nematodes present. Relative and absolute quantification estimates were comparable and resulted in strong positive correlations between the qPCR estimate and the actual number of nematodes present in the samples. The qPCR assay developed here provides the ability to quickly identify and quantify cryptic nematode species and will facilitate their study in laboratory and field settings.