World's Rarest Research Articles

Diagnosing Zygosity in Giant Panda Twins Using Short Tandem Repeats.

The giant panda, native to mountains of south-west China, is one of the world's rarest bear species and is subject to considerable conservation effort. In captivity, the proportion of twins accounts for 54% of the total number of births. To date, little is known about zygosity in panda populations - specifically, the proportion of monozygotic and dizygotic twins. In this study, we used 10 microsatellite markers for reliable zygosity testing, and the probability of monozygotic twins was 99.963% when all 10 markers were concordant. Out of 43 studied twin pairs, no MZ twins were found, indicating that there may be no identical panda twins (or the incidence is very low). We speculate that the fertilized eggs of giant pandas do not have the capability to split into two identical embryos, or that this ability is very poor, which is likely due to delayed implantation that is common in bear species. The results of this study deepen our understanding of giant panda breeding, yield insight into panda twins' likely mechanism of formation, and reduce the uncertainty of individual identity in wild population surveys.

Reproductive Ecology of the Brazilian Merganser (Mergus octosetaceus) in Serra da Canastra National Park and Adjacent Areas, Minas Gerais, Brazil

The Brazilian Merganser (Mergus octosetaceus) is globally classified as a Critically Endangered species and is one of the world's rarest waterbirds. The breeding ecology of this species was studied between 2005 and 2016 in the region of the Serra da Canastra National Park, Minas Gerais, Brazil. Between two and six nests were followed each year, with mean of 4.1 (n = 18 nests). Mean clutch size was 6.7 ± 0.9 (n = 31 clutches) with a range of five to eight eggs per nest. Average incubation constancy was 88.3% (n = 3 nests) and ranged from 86.7% to 90.7%. Mean incubation temperature and humidity were obtained from three nests and ranged from 33.6 °C to 33.8 °C and 65.9% to 70.2% respectively. The nest success was 77.1%, and the duckling survival (up to 8 weeks) was 53.8%. Nest predation was relatively low at 7.9%, and the annual reproductive output was 4.7 ducklings/female. Data on breeding ecology is fundamental in guiding conservation strategies, both in the field and in captivity.

Conservation Biology: A Walking Stick’s Redux on Lord Howe Island

Arguably the world's rarest insect - the Lord Howe Island 'tree lobster'- is being brought back from the brink. A recent study has confirmed the identity of this species using genomic data, which backstops its reintroduction to this World Heritage listed oceanic island.

Museum Genomics Confirms that the Lord Howe Island Stick Insect Survived Extinction

The Lord Howe Island stick insect, Dryococelus australis, was once common on the island but was driven to extinction after the arrival of ship rats in the early 20th century [1, 2]. It was thought to be extinct for decades, until a tiny population of similar-looking stick insects was discovered 20km away, on the islet of Ball's Pyramid, in 2001 [2]. Individuals from this population are currently being reared in Australia and elsewhere in the world, with the eventual goal of recolonizing Lord Howe Island [3]. Recent surveys of the wild population on Ball's Pyramid suggest that it is among the world's rarest species. However, there are significant morphological differences between Ball's Pyramid and museum specimens, and there has never been a genetic confirmation of the rediscovered population's species identity. Because Dryococelus is monotypic, there are also no known extant relatives for comparison. Using shotgun genomic data from the Ball's Pyramid population, we assembled a draft genome and the complete mitochondrial genome. We found that the genome is massive, over 4 Gb in size, and is most likely hexaploid. We re-sequenced mitochondrial genomes from historic museum specimens collected on Lord Howe Island before the extinction event. Sequence divergence between the two populations is less than 1% and is within the range of intraspecific differences between the museum specimens, suggesting that they are conspecific and that D.australis has successfully evaded extinction so far. This work highlights the importance of museum collections for taxonomic validation in the context of ongoing conservation efforts.

Local awareness and perceptions: consequences for conservation of marsh habitat at Lake Alaotra for one of the world's rarest lemurs

AbstractManagement and monitoring of community-based protected areas in Madagascar remain challenging because of a lack of financial, human and technical resources, and capacity. At Lake Alaotra, conversion of marshland for rice cultivation and a lack of effective habitat protection have pushed the locally endemic Alaotra gentle lemur Hapalemur alaotrensis to the brink of extinction. The highest density of the species is found in the locally managed Park Bandro, a high-priority conservation zone within the Lake Alaotra New Protected Area. We evaluated local awareness and perceptions of Park Bandro, and discussed preferred management options with local communities. Two questionnaire surveys were carried out, one with 180 participants at six sites around the lake and marsh, and another with 50 participants in the village adjacent to Park Bandro. The majority of participants knew of the existence of Park Bandro but most did not know its purpose or size. Values and perceptions of local communities were influenced by occupation and distance to the Park, with fishers being most aware of the Park. We found that local people had a high level of environmental awareness and were willing to discuss zonation and alternative resource management strategies as long as these activities could provide a tangible livelihood benefit. Lack of awareness among local resource users regarding the purpose and status of protected areas such as Park Bandro is a challenge that needs to be addressed, and one that is relevant for environmental education and management of protected areas throughout Madagascar.

Larva of one of the world's rarest and most threatened damselflies: Spesbona angusta (Odonata: Platycnemididae)

Larva of one of the world's rarest and most threatened damselflies: Spesbona angusta (Odonata: Platycnemididae)

Phylogenetic relationships, song and distribution of the endangered Rufous‐headed Robin Larvivora ruficeps

The Rufous‐headed Robin Larvivora ruficeps is one of the world's rarest and least known birds. We summarize the known records since it was first described in 1905 from Shaanxi Province, central China. All subsequent Chinese records are from seven adjacent localities in nearby Sichuan Province. We studied its phylogenetic position for the first time using mitochondrial and nuclear markers for all species of Larvivora and a broad selection of other species in the family Muscicapidae. Our results confirmed that L. ruficeps is appropriately placed in the genus Larvivora, and suggested that it is sister to the Rufous‐tailed Robin Larvivora sibilans, with these two forming a sister clade to a clade comprising both the Japanese Robin Larvivora akahige and Ryukyu Robin Larvivora komadori. Siberian Blue Robin Larvivora cyane and Indian Blue Robin Larvivora brunnea form the sister clade to the other Larvivora species. In contrast, song analyses indicated that the song of L. ruficeps is most similar to that of L. komadori, whereas the song of L. sibilans is relatively more similar to that of L. akahige, and songs of L. cyane and L. brunnea closely resemble each other. We used ecological niche modelling to estimate the suitable habitats of L. ruficeps based on the records from breeding grounds, suggesting that north and central Sichuan, south Gansu, south Shaanxi and south‐east Tibet are likely to contain the most suitable habitats for this species.

Spatiotemporal requirements of the Hainan gibbon: Does home range constrain recovery of the world's rarest ape?

Re-evaluation reveals Hainan gibbon home range as c. 1-2 km2 . Hainan gibbon home range is, therefore, similar to other Nomascus gibbons. Limited data for extremely rare species does not necessarily prevent derivation of robust home range estimates.

How many remnant gibbon populations are left on Hainan? Testing the use of local ecological knowledge to detect cryptic threatened primates.

For Critically Endangered "species of extreme rarity," there is an urgent need to clarify the potential survival of remnant populations. Such populations can be difficult to detect using standard field methods. Local ecological knowledge (LEK) represents an important alternative source of information, but anecdotal reports of rare or possibly extinct species can contain uncertainty and error. The Hainan gibbon (Nomascus hainanus), the world's rarest primate species, is confirmed to only survive as a tiny remnant population in Bawangling National Nature Reserve, China, but unverified gibbon sightings have been reported from other forest areas on Hainan. We conducted a large-scale community interview survey to gather new data on patterns of primate LEK from 709 respondents around seven reserves across Hainan, to investigate the possibility of gibbon survival outside Bawangling and assess whether LEK can provide useful information for conservation management of cryptic remnant populations. Comparative LEK data for gibbons and macaques are consistent with independent data on the relative status of these species across Hainan. Local awareness and experience of gibbons was low across Hainan, including at Bawangling, but we recorded recent anecdotal gibbon reports from most reserves. A follow-up field survey at Limushan Provincial Nature Reserve did not detect gibbons, however, and documented intensive wildlife exploitation within this reserve. All other surveyed landscapes showed some statistically lower levels of respondent awareness, experience, or sighting histories of gibbons compared to Bawangling, and are therefore considered biologically unlikely to support gibbons. Unverified LEK data can provide important insights into the possible status of cryptic remnant populations when assessed carefully and critically in relation to data from known populations.

Immediate action required to prevent another Australian avian extinction: the King Island Scrubtit

For small and rapidly declining populations acting fast to prevent extinction is crucial. However, many endangered species receive little attention or management action. Action paralysis can prevail for several reasons, particularly for data deficient species when conservation resources are scarce. Here we draw attention to one of the world's rarest birds, the King Island Scrubtit (Acanthornis magnus greenianus), a subspecies of a monotypic genus. Recognised as critically endangered for more than two decades, conservation action is virtually non-existent despite a rapid population decline. To establish current baseline information using a repeatable cost-effective monitoring methodology we surveyed 154 sites at eight locations as well as additional sites within the agricultural matrix. We detected the King Island Scrubtit at 28 sites in three locations (Nook Swamp, Colliers Swamp and Pegarah State Forest). At these locations, we estimated overall occupancy to be 0.35 (s.e. 0.05) and detectability to be 0.68 (s.e. 0.05) during a single site visit. We estimate the current area of occupancy of the bird to be <1 km2, declining. This study documents previously unrecognised threats (acid sulfate soils, macropod browsing and wind-throw) and provides a path forward to population recovery. Our results highlight the need for urgent action to prevent Australia’ s next avian extinction.

Assessing current genetic status of the Hainan gibbon using historical and demographic baselines: implications for conservation management of species of extreme rarity

Evidence-based conservation planning is crucial for informing management decisions for species of extreme rarity, but collection of robust data on genetic status or other parameters can be extremely challenging for such species. The Hainan gibbon, possibly the world's rarest mammal, consists of a single population of ~25 individuals restricted to one protected area on Hainan Island, China, and has persisted for over 30years at exceptionally low population size. Analysis of genotypes at 11 microsatellite loci from faecal samples for 36% of the current global population and tissue samples from 62% of existing historical museum specimens demonstrates limited current genetic diversity (Na=2.27, Ar=2.24, He =0.43); diversity has declined since the 19th century and even further within the last 30years, representing declines of ~30% from historical levels (Na=3.36, Ar=3.29, He =0.63). Significant differentiation is seen between current and historical samples (FST =0.156, P=0.0315), and the current population exhibits extremely small Ne (current Ne =2.16). There is evidence for both a recent population bottleneck and an earlier bottleneck, with population size already reasonably low by the late 19th century (historical Ne =1162.96). Individuals in the current population are related at the level of half- to full-siblings between social groups, and full-siblings or parent-offspring within a social group, suggesting that inbreeding is likely to increase in the future. The species' current reduced genetic diversity must be considered during conservation planning, particularly for expectations of likely population recovery, indicating that intensive, carefully planned management is essential.

The rarest of them all

When Sam Turvey stared into the face of a Hainan gibbon he knew he had to join the effort to save the world's rarest mammal

International action required to rescue world's rarest plant

International action required to rescue world's rarest plant

Identifying environmental versus phylogenetic correlates of behavioural ecology in gibbons: implications for conservation management of the world's rarest ape.

BackgroundFor conservation of highly threatened species to be effective, it is crucial to differentiate natural population parameters from atypical behavioural, ecological and demographic characteristics associated with human disturbance and habitat degradation, which can constrain population growth and recovery. Unfortunately, these parameters can be very hard to determine for species of extreme rarity. The Hainan gibbon (Nomascus hainanus), the world’s rarest ape, consists of a single population of c.25 individuals, but intensive management is constrained by a limited understanding of the species’ expected population characteristics and environmental requirements. In order to generate a more robust evidence-base for Hainan gibbon conservation, we employed a comparative approach to identify intrinsic and extrinsic drivers of variation in key ecological and behavioural traits (home range size, social group size, mating system) across the Hylobatidae while controlling for phylogenetic non-independence.ResultsAll three studied traits show strong phylogenetic signals across the Hylobatidae. Although the Hainan gibbon and some closely related species have large reported group sizes, no observed gibbon group size is significantly different from the values expected on the basis of phylogenetic relationship alone. However, the Hainan gibbon and two other Nomascus species (N. concolor, N. nasutus) show home range values that are higher than expected relative to all other gibbon species. Predictive models incorporating intraspecific trait variation but controlling for covariance between population samples due to phylogenetic relatedness reveal additional environmental and biological determinants of variation in gibbon ranging requirements and social structure, but not those immediately associated with recent habitat degradation.ConclusionsOur study represents the first systematic assessment of behavioural and ecological trait patterns across the Hylobatidae using recent approaches in comparative analysis. By formally contextualising the Hainan gibbon’s observed behavioural and ecological characteristics within family-wide variation in gibbons, we are able to determine natural population parameters expected for this Critically Endangered species, as well as wider correlates of variation for key population characteristics across the Hylobatidae. This approach reveals key insights with a direct impact on future Hainan gibbon conservation planning, and demonstrates the usefulness of the comparative approach for informing management of species of conservation concern.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0430-1) contains supplementary material, which is available to authorized users.

Conserving the world's rarest ape: action planning for the Hainan gibbon

Conserving the world's rarest ape: action planning for the Hainan gibbon

In search of lost frogs: the campaign to rediscover the world's rarest amphibans

In search of lost frogs: the campaign to rediscover the world's rarest amphibans

The Sri Lankan torrent toads (Bufonidae: Adenominae: Adenomus): species boundaries assessed using multiple criteria.

The bufonid genus Adenomus, an endemic of the montane and lowland rainforests of central and south-western Sri Lanka, has been considered to comprise of three species, viz. A. kelaartii, A. dasi and A. kandianus, the last of which has been recently highlighted as "the world's rarest toad". We conducted a survey across the known range of Adenomus and used multiple criteria to delineate species boundaries within the genus. These include: a molecular phylogeny based on a 16S ribosomal RNA gene fragment; an examination of the external morphology of adults and larvae, and the skeletal morphology of adults; a bioacoustic analysis; and ecological niche modelling. We show that Adenomus is monophyletic and that it comprises only two species: A. kelaartii and A. kandianus, with A. dasi being a junior synonym of the latter. For the two valid species of Adenomus, we provide detailed osteological descriptions; clarify the distribution patterns; and provide genetic data to facilitate their scientific conservation management.

Interview-based sighting histories can inform regional conservation prioritization for highly threatened cryptic species.

The use of robust ecological data to make evidence-based management decisions is frequently prevented by limited data quantity or quality, and local ecological knowledge (LEK) is increasingly seen as an important source of information for conservation. However, there has been little assessment of LEK's usefulness for informing prioritization and management of landscapes for threatened species, or assessing comparative species status across landscapes.A large-scale interview survey in the Annamite Mountains (Vietnam and Lao PDR) compiled the first systematic LEK data set for saola Pseudoryx nghetinhensis, one of the world's rarest mammals, and eight other ungulates. Saola conservation is hindered by uncertainty over continued presence across much of its proposed distribution. We analysed comparative LEK-based last-sighting data across three landscapes to determine whether regional sighting histories support previous suggestions of landscape importance for saola conservation (Hue-Quang Nam: top-priority Vietnamese landscape; Pu Mat: lower priority Vietnamese landscape; Viengthong: high-priority Lao landscape) and whether they constitute an effective spatial prioritization tool for cryptic species management.Wild pig and red muntjac may be the only Annamite ungulates with stable populations; the regional status of all other species appears to be worse. Saola have declined more severely and/or are significantly rarer than most other ungulates and have been seen by relatively few respondents. Saola were also frequently considered locally rarest or declining, and never as species that had not declined.In contrast to other species, there are no regional differences in saola sighting histories, with continued persistence in all landscapes challenging suggestions that regional status differs greatly. Remnant populations persist in Vietnam despite heavy hunting, but even remote landscapes in Lao may be under intense pressure.Synthesis and applications. Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species.Our local ecological knowledge data suggest that intact saola populations probably no longer exist, but individuals persist in all three landscapes, making management activities to reduce hunting pressure on ungulates in each landscape a conservation priority. Analysis of last-sighting histories can constitute an important conservation tool when robust data are otherwise unavailable, and collection of last-sighting records should be incorporated more widely into field studies and management of other highly threatened, cryptic species.

Do Introduced Mammals Chronically Impact the Breeding Success of the World's Rarest Albatross?

Introduced mammals may have deleterious effects on avifauna. We investigated whether such species may be affecting the breeding success of the critically endangered Amsterdam Albatrosses Diomedea amsterdamensis on its remote breeding island. Twelve camera-traps deployed near albatross nests during the chick brooding period in 2011 captured 25,000 pictures. Two of them showed Black Rats Rattus rattus, but without revealing evidence of any direct interaction between the two species. Breeding success in 2011 was similar to that in previous years (60%). Our survey suggests that introduced mammals may not currently represent a primary direct threat to this population, but they might amplify the risks of chick mortality in case of disease outbreaks.

Facing extinction: the world's rarest birds and the race to save them

Facing extinction: the world's rarest birds and the race to save them