Biological inventory of Ranomafana National Park tetrapods using leech-derived iDNA

Testing and optimizing metabarcoding of iDNA from dung beetles to sample mammals in the hyperdiverse Neotropics

Over the past few years, insects have been used as samplers of vertebrate diversity by assessing the ingested-derived DNA (iDNA), and dung beetles have been shown to be a good mammal sampler given their broad feeding preference, wide distribution and easy sampling. Here, we tested and optimized the use of iDNA from dung beetles to assess the mammal community by evaluating if some biological and methodological aspects affect the use of dung beetles as mammal species samplers. We collected 403 dung beetles from 60 pitfall traps. iDNA from each dung beetle was sequenced by metabarcoding using two mini-barcodes (12SrRNA and 16SrRNA). We assessed whether dung beetles with different traits related to feeding, nesting and body size differed in the number of mammal species found in their iDNA. We also tested differences among four killing solutions in preserving the iDNA and compared the effectiveness of each mini barcode to recover mammals. We identified a total of 50 mammal OTUs (operational taxonomic unit), including terrestrial and arboreal species from 10 different orders. We found that at least one mammal-matching sequence was obtained from 70% of the dung beetle specimens. The number of mammal OTUs obtained did not vary with dung beetle traits as well as between the killing solutions. The 16SrRNA mini-barcode recovered a higher number of mammal OTUs than 12SrRNA, although both sets were partly non-overlapping. Thus, the complete mammal diversity may not be achieved by using only one of them. This study refines the methodology for routine assessment of tropical mammal communities via dung beetle 'samplers' and its universal applicability independently of the species traits of local beetle communities.

Long forgotten record of a freshwater leech on Madagascar indicates a host-associated dispersal event from continental Africa

Madagascar houses a peculiar and largely endemic biota, having ancient Gondwanan affinities. However, the faunal composite of many invertebrate groups on the island is poorly known. For a long time, it was believed that the freshwater leech fauna of Madagascar contains a salifid species (Salifidae) only. Here, we report on a historical record of Placobdelloides multistriatus (Johansson, 1909) (Glossiphoniidae), a widespread African species, from Andrahomana, Southern Madagascar. Franz Sikora (1863-1902), an Austrian traveler and collector, who visited Andrahomana in 1899 to excavate fossils from a cave, collected the leech sample. The two specimens were obtained from an unspecified turtle species. We assume that P. multistriatus may have arrived to Madagascar relatively recently (i.e., in the Late Pleistocene or Holocene) via a long-distance dispersal event from continental Africa with its reptilian hosts such as the Nile crocodile and marsh terrapin. Based on a review of the body of available literature, two more freshwater leech species are known to occur on Madagascar: Linta be Westergren & Siddall, 2004 (Salifidae) and Alboglossiphonia sp. (Glossiphoniidae). Our findings indicate that Madagascar houses at least three freshwater leech species and that some additional taxa may have been overlooked there due to the scarcity of sampling efforts in the island’s freshwater bodies.

Dung beetles as samplers of mammals in Malaysian Borneo-a test of high throughput metabarcoding of iDNA

Invertebrate-derived DNA (iDNA) sampling in biodiversity surveys is becoming increasingly widespread, with most terrestrial studies relying on DNA derived from the gut contents of blood-feeding invertebrates, such as leeches and mosquitoes. Dung beetles (superfamily Scarabaeoidea) primarily feed on the faecal matter of terrestrial vertebrates and offer several potential benefits over blood-feeding invertebrates as samplers of vertebrate DNA. Importantly, these beetles can be easily captured in large numbers using simple, inexpensive baited traps, are globally distributed, and occur in a wide range of habitats. To build on the few existing studies demonstrating the potential of dung beetles as sources of mammalian DNA, we subjected the large-bodied, Bornean dung beetle (Catharsius renaudpauliani) to a controlled feeding experiment. We analysed DNA from gut contents at different times after feeding using qPCR techniques. Here, we first describe the window of DNA persistence within a dung beetle digestive tract. We found that the ability to successfully amplify cattle DNA decayed over relatively short time periods, with DNA copy number decreasing by two orders of magnitude in just 6 h. In addition, we sampled communities of dung beetles from a lowland tropical rainforest in Sabah, Malaysia, in order to test whether it is possible to identify vertebrate sequences from dung beetle iDNA. We sequenced both the gut contents from large dung beetle species, as well as whole communities of smaller beetles. We successfully identified six mammalian species from our samples, including the bearded pig (Sus barbatus) and the sambar deer (Rusa unicolor)—both vulnerable species on the IUCN red list. Our results represent the first use of dung beetle iDNA to sample Southeast Asian vertebrate fauna, and highlight the potential for dung beetle iDNA to be used in future biodiversity monitoring surveys.

The potential of aquatic bloodfeeding and nonbloodfeeding leeches as a tool for iDNA characterisation

Leeches play important roles in food webs due to their abundance, diversity and feeding habits. Studies using invertebrate‐derived DNA (iDNA) extracted from leech gut contents to target vertebrate DNA have focused on the Indo‐Pacific region and mainly leveraged the leech family Haemadipsidae, composed of bloodfeeding terrestrial leeches, while predatory, fluid/tissue‐feeding and aquatic bloodfeeding species have been largely disregarded. While there is some general knowledge regarding the taxonomic groups that leeches prefer to feed on, detailed taxonomic resolution is missing and, therefore, their potential use for monitoring animals is unknown. In this study, 116 leeches from 12 species (six families) and spanning the three feeding habits were collected in Mexico and Canada. We used DNA metabarcoding to investigate their diet and assess their potential use for biodiversity monitoring. We detected vertebrates from five orders including fish, turtles and birds in the diet of aquatic bloodfeeding leeches; eight invertebrate orders of annelids, arthropods and molluscs in leeches that feed on body fluids and tissues; and 10 orders of invertebrates belonging to Arthropoda and Annelida, as well as one vertebrate and one parasitic nematode, in predatory leeches. These results show the potential use of iDNA from aquatic bloodfeeding leeches for retrieving vertebrate taxa, and from predatory and fluid‐feeding leeches for invertebrates. Our study provides information about the dietary range of freshwater leeches and one terrestrial leech and contributes proof‐of‐concept for the use of these leeches for animal monitoring, expanding our knowledge of the use of iDNA from leech gut contents to North America.

Host-parasite relationships between seabirds and the haemadipsid leech Chtonobdella palmyrae (Annelida: Clitellata) inhabiting oceanic islands in the Pacific Ocean

The duognathous haemadipsid leeches of the genus Chtonobdella show a trans-oceanic distribution throughout the Indo-Pacific region. Although passive long-distance dispersal (LDD) of Chtonobdella leeches by birds has been suggested, little is known about the host-parasite relationships between avian hosts and Chtonobdella leeches. In the current study, we investigated Chtonobdella leech infestations of the eyes and other mucus membranes of migratory procellariiform seabirds, Pterodroma hypoleuca and Oceanodroma tristrami, captured at six locations in the Bonin Islands, Honshu and Okinawa Island, Japan. Analyses of the partial sequences of 18S rRNA, 28S rRNA, and mitochondrial cytochrome c oxidase subunit I (COI) and morphological examination of the specimens demonstrated that the Chtonobdella leeches belonged to Chtonobdella palmyrae, which is indigenous to Palmyra Atoll in the Northern Line Islands. A dominant COI sequence type was observed in samples from all six sites; therefore, C. palmyrae almost surely dispersed approximately 1000 km by infesting the eyes and mucus membranes of procellariiform seabirds. The host-parasite relationships between procellariiform seabirds and C. palmyrae provide explicit evidence of the LDD of duognathous haemadipsid leeches. The taxonomic status of Haemadipsa zeylanica ivosimae from the Volcano Islands is also briefly discussed.