Surveying frogs from the bellies of their parasites: Invertebrate-derived DNA as a novel survey method for frogs

Abstract

Biodiversity conservation is reliant on thorough species occurrence data. However, the collection of such data is often difficult for species with poor detectability. Recently, invertebrate-derived DNA (iDNA) has emerged as a potentially powerful survey method to increase the detectability of terrestrial vertebrates. Parasitic invertebrates are effective samplers of some vertebrate diversity and can be used to detect and identify their host species by sequencing the DNA contained in their meals. Among taxa that can be very difficult to detect using traditional survey methods are many frog species, which are often of a high conservation priority. However, the potential for frog-specific iDNA surveys has not been explored; most iDNA surveys have targeted mammals. We carried out traditional audio-visual and iDNA frog surveys in eastern Australia to determine whether frog-biting midges (Corethrella and Sycorax spp.) can be used as an effective survey method for frogs. The frog species detected through each method differed. Five species were detected only during traditional surveys, three by both methods, and one exclusively via iDNA. We demonstrate for the first time that iDNA can be used in targeted surveys of frog diversity and that it may increase the detectability of some species compared to traditional surveys. iDNA holds particular promise in the search for rare species, including those that are missing, feared extinct, and may also be useful in biosecurity, detecting invasive species.

Keywords

• Detectability
• iDNA
• Frog
• Survey
• Corethrella
• Sycorax