Mind the gaps: investigating the cause of the current range disjunction in the Cape Platanna, Xenopus gilli (Anura: Pipidae)

Low-lying areas of the Cape at Africa’s south-westernmost tip have undergone dramatic marine-remodelling, with regular changes in sea-level following glacial cycles. Species for which marine barriers are impenetrable underwent concomitant radical distribution changes which may account for current range disjunctions. The Cape platanna, Xenopus gilli, is a frog distributed in only three disjunt areas within low-lying regions of the southwestern Cape. We determined the relationship between frogs from these three disjunct areas, by using a combination of morphometric analysis and mtDNA (ND2 and 16S fragments) sequences of 130 frogs from eight ponds. Coalescent analyses on molecular data dated the divergence in two major clades to around 4.6 Mya, a period during which major uplifting on the eastern side of the subcontinent caused climate changes throughout southern Africa. Principal components analysis showed significant morphometric differences between each clade on head and limb measurements. Consistent differences in ventral colouration and patterning were also observed. We report on increased levels of hybridisation with X. laevis throughout the range of X. gilli, which reaches at least 27% hybrids in some ponds. Urgent conservation actions are required to control habitat loss from alien invasive vegetation, and prevent introgression with the domestic-exotic, X. laevis

Comparison of eDNA and visual surveys for rare and cryptic bromeliad-dwelling frogs

Surveys of rare or cryptic species may miss individuals or populations that are actually present. Despite the increasing use of environmental DNA (eDNA) analysis to survey species in ponds, rivers, and lakes, very few studies have attempted to use eDNA for the detection of species using very small water bodies such as those accumulated within plants. Our aim was to investigate the feasibility of an eDNA sampling method for detecting Crossodactylodes itambe, an endemic bromeliad-dwelling frog from a remote location in Brazil. We collected water samples from 19 bromeliads for which we had observational data from direct visual surveys. We compared occupancy estimated from direct observations with the results from quantitative real-time PCR based eDNA assays. For observational surveys, we used a single season occupancy model. We applied a novel Bayesian occupancy model to estimate occupancy from eDNA samples, as well as false positives and false negatives at different stages of the workflow. eDNA from bromeliad tanks provided reliable estimates, with very low error levels and improved detection when compared to detectability from direct observation. Estimated occupancies using eDNA and visual survey methods were similar. The method is feasible for species restricted to small water bodies and exposed to direct UV radiation, and particularly useful to survey remote locations and confirm species presence. eDNA analysis provides a viable alternative to destructive sampling of bromeliads or direct observation methods that require logistically challenging repeated observations. Therefore, eDNA methods may be widely applicable to sampling programmes of other amphibians that live in plant

Hygiene and biosecurity protocols reduce infection prevalence but do not improve fledging success in an endangered parrot

Emerging Infectious Diseases (EIDs) are recognised as global extinction drivers of threatened species. Unfortunately, biodiversity managers have few tested solutions to manage them when often the desperate need for solutions necessitates a response. Here we test in situ biosecurity protocols to assess the efficacy of managing Psittacine beak and feather disease (PBFD), one of the most common and emergent viral diseases in wild parrots (Psittaciformes) that is currently affecting numerous threatened species globally. In response to an outbreak of PBFD in Mauritius “echo” parakeets (Psittacula eques), managers implemented a set of biosecurity protocols to limit transmission and impact of Beak and feather disease virus (BFDV). Here we used a reciprocal design experiment on the wild population to test whether BFDV management reduced viral prevalence and viral load, and improved nestling body condition and fledge success. Whilst management reduced the probability of nestling infection by approximately 11% there was no observed impact on BFDV load and nestling body condition. In contrast to expectations there was lower fledge success in nests with added BFDV biosecurity (83% in untreated vs. 79% in treated nests). Our results clearly illustrate that management for wildlife conservation should be critically evaluated through targeted monitoring and experimental manipulation, and this evaluation should always focus on the fundamental objective of conservation

Beak and feather disease virus in wild and captive parrots: an analysis of geographic and taxonomic distribution and methodological trends

Psittacine beak and feather disease (PBFD) has emerged in recent years as a major threat to wild parrot populations and is an increasing concern to aviculturists and managers of captive populations. Pathological and serological tests for screening for the presence of beak and feather disease virus (BFDV) are a critical component of efforts to manage the disease and of epidemiological studies. Since the disease was first reported in the mid-1970s, screening for BFDV has been conducted in numerous wild and captive populations. However, at present, there is no current and readily accessible synthesis of screening efforts and their results. Here, we consolidate information collected from 83 PBFD- and BFDV-based publications on the primary screening methods being used and identify important knowledge gaps regarding potential global disease hotspots. We present trends in research intensity in this field and critically discuss advances in screening techniques and their applications to both aviculture and to the management of threatened wild populations. Finally, we provide an overview of estimates of BFDV prevalence in captive and wild flocks alongside a complete list of all psittacine species in which the virus has been confirmed. Our evaluation highlights the need for standardised diagnostic tests and more emphasis on studies of wild populations, particularly in view of the intrinsic connection between global trade in companion birds and the spread of novel BFDV strains into wild populations. Increased emphasis should be placed on the screening of captive and wild parrot populations within their countries of origin across the Americas, Africa and Asia

Data from: Individual consumption of supplemental food as a predictor of reproductive performance and viral infection intensity

1.Supplemental food is often provided to threatened species in order to maintain or enhance reproductive fitness and thus population growth. However, its impact on individual reproductive fitness is rarely evaluated, despite being associated with both positive and negative consequences. 2. We used stable isotope analyses to characterise the relative proportional consumption of supplemental food and quantitative polymerase chain reaction (qPCR) to assess beak and feather disease viral infection intensity among parakeets. Life-history and nest-site data from a long-term monitoring effort was incorporated. 3. Older females benefitted the most from supplemental feeding; demonstrated by a greater reproductive uplift than younger females. There were no strong predictors of viral infection levels among nestlings. 4. Reproductive fitness, measured by the number of fledglings produced per brood, was positively associated with proportional dietary content of supplemental food among adult parakeets and breeding pairs that nested closer to feeding stations consumed more supplemental food than those nesting further away. 5. Synthesis and applications. Our study demonstrates that supplementary feeding can lead to an overall increase in population growth. However, by characterising individual consumption, we also reveal subtle patterns of use and differential benefits on reproductive fitness within a population. Manipulating the delivery of supplemental food may help to reduce demand on finite resources or target the proportion of a population that derives the most benefit, but is associated with trade-offs in fecundity. For example the use of, and access to feeding stations could potentially be targeted towards specific individuals or, positioned in the habitats most deficient in native food. However, increasing reproductive fitness in one component of the population may be accompanied by a decrease in another. This knowledge can be incorporated into adaptive management strategies that aim to fulfil specific objectives associated with species recovery and long-term viability as long as the relative importance of each objective is be considered

Individual consumption of supplemental food as a predictor of reproductive performance and viral infection intensity

1. Supplemental food is often provided to threatened species in order to maintain or enhance reproductive fitness and thus population growth. However, its impact on individual reproductive fitness is rarely evaluated, despite being associated with both positive and negative consequences. 2. We used stable isotope analyses to characterise the relative proportional consumption of supplemental food and quantitative polymerase chain reaction to assess beak and feather disease viral infection intensity among parakeets. Life- history and nest- site data from a long-term monitoring effort was incorporated. 3. Older females benefitted the most from supplemental feeding; demonstrated by a greater reproductive uplift than younger females. There were no strong predictors of viral infection levels among nestlings. 4. Reproductive fitness, measured by the number of fledglings produced per brood, was positively associated with proportional dietary content of supplemental food among adult parakeets and breeding pairs that nested closer to feeding stations consumed more supplemental food than those nesting further away. 5. Synthesis and applications. Our study demonstrates that supplementary feeding can lead to an overall increase in population growth. However, by characterising individual consumption, we also reveal subtle patterns of use and differential benefits on reproductive fitness within a population. Manipulating the delivery of supplemental food may help to reduce demand on finite resources or target the proportion of a population that derives the most benefit, but is associated with trade-offs in fecundity. For example, the use of and access to feeding stations could potentially be targeted towards specific individuals, or positioned in the habitats most deficient in native food. However, increasing reproductive fitness in one component of the population may be accompanied by a decrease in another. This knowledge can be incorporated into adaptive management strategies that aim to fulfil specific objectives associated with species recovery and long-term viability as long as the relative importance of each objective is be considered