Short Communication Non-Invasive Genetic Identification Confirms the Presence of the Endangered Okapi Okapia Johnstoni South-West of the Congo River
Total Page:16
File Type:pdf, Size:1020Kb
Short Communication Non-invasive genetic identification confirms the presence of the Endangered okapi Okapia johnstoni south-west of the Congo River D AVID W. G. STANTON,JOHN H ART,ASHLEY V OSPER,NOËLLE F. KÜMPEL J INLIANG W ANG,JOHN G. EWEN and M ICHAEL W. BRUFORD Abstract The okapi Okapia johnstoni, a rainforest giraffid he okapi Okapia johnstoni is a monotypic species of the endemic to the Democratic Republic of Congo, was recate- Tfamily Giraffidae, endemic to the Democratic Republic gorized as Endangered on the IUCN Red List in . of Congo. In the species was recategorized as Historical records and anecdotal reports suggest that a dis- Endangered on the IUCN Red List but there is still a lack junct population of okapi may have occurred south-west of of information regarding its range and population sizes the Congo River but the current distribution and status (Mallon et al., ). Most of the okapi’s range lies to the of the okapi in this region are not well known. Here we de- north and east of the Congo River (Kingdon, ; Stuart scribe the use of non-invasive genetic identification for this & Stuart, ; IUCN, ; Hart, ). However, there species and assess the success of species identification from are anecdotal historical (dating back at least to ; Royal dung in the wild, which varied throughout the range. This Museum for Central Africa, Tervuren) and present-day re- variation is probably attributable to varying okapi popu- ports of okapi also occurring south-west of the river (Fig. ), lation densities and/or different sample collection strategies although these are unconfirmed. It is important to deter- across the okapi’s distribution. Okapi were confirmed to mine the validity of these reports because rediscovery of a occur south-west of the Congo River, in scattered localities southern okapi population would imply a geographically west of the Lomami River. We demonstrated that non-in- and potentially evolutionarily distinct population and re- vasive genetic methods can provide information on the dis- inforce efforts to gazette protected areas within this region. tribution of cryptic, uncommon species that is difficult to Okapi are elusive (the first camera-trap image of an okapi obtain by other methods. Further investigation is required was obtained in ; Nixon & Lusenge, ) and are to genetically characterize the okapi across its range and consequently difficult to monitor in the wild. Previously, to investigate the biogeographical processes that have led dung counts have been used to determine okapi presence/ to the observed distribution of okapi and other fauna in absence (Beyers, ; Vosper et al., ). However, studies the region. of other species have shown that accurate visual identifi- cation of animal dung can be difficult (Busby et al., ; Keywords Democratic Republic of Congo, dung sample, Faria et al., ). According to field researchers okapi Endangered, endemic species, Giraffidae, okapi, protected dung is likely to be confused with bongo Tragelaphus eury- area cerus dung in the wild (J. Hart & S. Nixon, pers. comm.). This paper contains supplementary material that can be Non-invasive genetic methods provide a useful way of test- found online at http://journals.cambridge.org ing this possibility (Taberlet & Luikart, ; Busby et al., ; Faria et al., ). Here we present an update on the distribution of the okapi south and west of the Congo River, based on genetic identification of putative okapi dung. Our results show the DAVID W. G. STANTON (Corresponding author) and MICHAEL W. BRUFORD School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK potential utility of this non-invasive, cost-effective method E-mail [email protected] as a means to confirm species’ identities where numbers JOHN HART Lukuru Foundation, Projet Tshuapa-Lomami-Lualaba, Kinshasa, are low and confusion with other species is possible. We Democratic Republic of Congo used two mitochondrial DNA (mtDNA) primers, OJ and ASHLEY VOSPER Wildlife Conservation Society, Okapi Faunal Reserve, OJ (OJ-F (–, based on Genbank okapi mt gen- Democratic Republic of Congo ome, Genbank accession number: NC_.): ATGA NOËLLE F. KÜMPEL Conservation Programmes, Zoological Society of London, – London, UK ATCGGAGGACAACCA, OJ -R ( ): GGCCTC TTCTTTGAGTCTTAGG, bp; OJ-F (–): JINLIANG WANG and JOHN G. EWEN Institute of Zoology, Zoological Society of – London, London, UK CCTAAGACTCAAAGAAGAGGCC, OJ -R ( ): Received March . Revision requested June . TGCTGCGTTAAGGCTGTG, bp) from Stanton et al. Accepted July . First published online November . (). Primer OJ is sited in the okapi cytochrome b Oryx, 2016, 50(1), 134–137 © 2014 Fauna & Flora International doi:10.1017/S0030605314000593 Downloaded from https://www.cambridge.org/core. IP address: 170.106.33.14, on 01 Oct 2021 at 04:55:18, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605314000593 Okapi south-west of the Congo River 135 FIG. 1 Map of the study area in the Democratic Republic of Congo, showing the locations where dung samples with viable DNA were found, and of historical records of okapi Okapia johnstoni presence (Royal Museum for Central Africa, Tervuren, and the Centre de Recherche en Science Naturelles, Lwiro, DRC). The study area is divided into four sampling regions. Areas with local knowledge of okapi presence and/ or evidence of okapi observed in a local village are delineated by dashed lines, based on information collected from the Okapi Conservation Workshop. (Cyt b) and tRNA genes, whereas the reverse primer for OJ is respectively. Products were visualized on a % agarose gel sited in the control region. Cyt b is usually more conserved and sequenced by Macrogen Europe. For successfully se- between taxa than the control region, and therefore whereas quenced PCR products, species were identified using the primer OJ may amplify DNA from other taxa as well as GenBank (BLAST) database. The formulae from Faria okapi, primer OJ should only amplify DNA from okapi. et al. () were used to quantify and describe the accuracy This combination of primers may therefore be useful for spe- of species identification based on the observed pattern of cies identification, based on their relative amplification suc- PCR bands on agarose gel before DNA sequencing had cesses, without the need for DNA sequencing. We analysed been carried out. These formulae estimate the error of omis- putative okapi dung samples collected during – sion (where dung from a given species is overlooked by this throughout the okapi’s known range. Seven samples were method), error of commission (where dung is incorrectly at- from sampling region , from region , seven from region tributed to a particular species) and identification accuracy and from region (Fig. ). Faecal samples were collected (rate of identification accuracy, both within species and either by () walking along randomly placed transects through overall). Here, the estimation of identification accuracy re- forest sites and collecting any faeces observed, or ()identify- flects only the accuracy of this method for identifying okapi ing putative okapi sign (dung or prints, for which the re- and is therefore equivalent to one minus the error of liability of correctly identifying okapi in the wild is omission. unknown) and searching the surrounding area for faeces. Of the dung samples tested did not amplify suc- Sampling methodology () was used in areas of high okapi cessfully using either of the mtDNA primers (four of seven density (the Okapi Faunal Reserve; Fig. )and()wasused (.%), sampling region ; of (.%), sampling re- in areas of low okapi density (everywhere else in the range gion ; four of seven (.%), sampling region ; of where faecal samples were found). Sample collection in the (.%), sampling region ), probably because of degraded Reserve was carried out as part of a separate large-mammal DNA. Details of OJ and OJ primer amplification and spe- survey (Vosper et al., ). Elsewhere in the range, areas for cies identification are in Supplementary Material . All sam- sample collection were chosen based on the historical distri- ples in which primer OJ could be amplified were okapi bution of okapi (Fig. ; Kingdon, ;Stuart&Stuart,; samples, based on a Genbank (BLAST) of sequenced PCR IUCN, ;Hart,), attempting to maximize spatial products. Primer OJ failed to amplify a fragment in all coverage within logistical limits. In sampling locations bongo samples. Successful PCR amplification of primer whereitwasnotclearwhetherdungpileswerefromoneor OJ can therefore be used to differentiate between okapi more individuals, samples were genotyped with microsatel- and bongo without the need for DNA sequencing, with pri- lites (Stanton et al., ) to distinguish between individuals. mer OJ acting as a positive control. Using the species Details of mtDNA PCR (polymerase chain reaction) re- identification formulae from Faria et al. () we estimate agents and conditions are in Supplementary Tables S &S, an error of omission of %, an error of commission of % Oryx, 2016, 50(1), 134–137 © 2014 Fauna & Flora International doi:10.1017/S0030605314000593 Downloaded from https://www.cambridge.org/core. IP address: 170.106.33.14, on 01 Oct 2021 at 04:55:18, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605314000593 136 D. W. G. Stanton et al. and an identification accuracy of % for correctly identify- apparently no longer exists in some areas where it was re- ing an okapi individual by the presence/absence of a band ported historically, whereas bongo appear to be more com- for primer OJ. This is because the primer pair OJ primes mon in the areas surveyed south-west of the Congo River in the Cyt b and tRNA genes, whereas the reverse primer of than in the Okapi Faunal Reserve (J. Hart, pers. comm.). the OJ primer pair primes in the control region, which is These differences in density may account for the higher oc- much less conserved between species (Supplementary currence of bongo dung samples in sampling region .In Table S).