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|Title:||An examination of the accuracy of a sequential PCR and sequencing test used to detect the incursion of an invasive species: the case of the red fox in Tasmania|
|Citation:||Journal of Applied Ecology, 2015; 52(3):562-570|
|David S. L. Ramsey, Anna J. MacDonald, Sumaiya Quasim, Candida Barclay, and Stephen D. Sarre|
|Abstract:||1. Polymerase chain reaction (PCR) diagnostic tests are increasingly applied to the identiﬁcation of wildlife. Yet rigorous veriﬁcation is rare and the estimation of test accuracy (the probability that true positive and true negative samples are correctly identiﬁed – test sensitivity and speciﬁcity, respectively), particularly in combination with sequencing, is uncommon. This is important because PCR-based tests are prone to contamination in sampling and the laboratory. 2. Here, we use an experimental case–control approach to estimate the sensitivity and speciﬁcity of a sequential PCR-based wildlife detection test used to identify incursions of red foxes into Tasmania from predator faeces (scats). 3. Our results show that the sensitivity of the fox test is high (˜94%) for the PCR-based test on its own, but this decreases to ~84% when combined with the DNA sequencing step. In contrast, the speciﬁcity increases from ~96% in the PCR -only test to ~99.6% after inclusion of the DNA sequencing step. 4. The intense public scrutiny of the fox eradication programme in Tasmania has undoubtedly inﬂuenced the application of a sequential PCR test that maximizes speciﬁcity at the expense of sensitivity and so increases the risk that scats containing fox DNA would not be detected. This could lead to the establishment of foxes in Tasmania as a consequence. 5. Synthesis and applications. Importantly, the estimation of the sensitivity and speciﬁcity of sequential tests enables decisions about the risk associated with mistaken identiﬁcation (i.e. false negatives vs. false positives) to be quantiﬁed for decision-makers. The cost of false-nega tive errors should be balanced against the costs of false-positive errors, which could include the expenditure incurred in the application of unnecessary management actions were foxes not in fact present. Understanding the risks and costs associated with both false-negative and false-positive errors is therefore a key component to the decision-making process for the management of the Tasmanian fox incursion.|
|Keywords:||Bayesian analysis; blind testing; predator faeces; scats, sensitivity; sequential test; speciﬁcity; trace DNA; Vulpes vulpes|
|Rights:||© 2015 The Authors. Journal of Applied Ecology © 2015 British Ecological Society|
|Appears in Collections:||Earth and Environmental Sciences publications|
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