Immune stress and diet influence reproductive fitness in male tuatara ().

The theoretical trade-off between immune and endocrine investment in mating animals has received mixed empirical support, particularly in reptiles. We investigated the relationship between male sexual characteristics, diet, and immune response to stress in an island population of tuatara () across two mating seasons. Tuatara are promiscuous, with a highly skewed mating system where males face significant competition for access to mates and postcopulatory competition for fertilization success.

Limited gut bacterial response of tuatara (Sphenodon punctatus) to dietary manipulation and captivity.

The bacteria of a host's digestive tract play crucial roles in digestion and pathogen resistance. Hosts living in captivity often have more human interaction and antibiotic use, in addition to differences in diet and environment, compared to their wild counterparts. Consequently, wild and captive animals frequently harbour different bacterial communities.

Gut microbiome of the sole surviving member of reptile order Rhynchocephalia reveals biogeographic variation, influence of host body condition and a substantial core microbiota in tuatara across New Zealand.

Tuatara are the sole extant species in the reptile order Rhynchocephalia. They are ecologically and evolutionarily unique, having been isolated geographically for ~84 million years and evolutionarily from their closest living relatives for ~250 million years. Here we report the tuatara gut bacterial community for the first time.

The effects of annual cycle, source population, and body condition on leukocyte profile and immune challenge in a basal reptile, the tuatara (Sphenodon punctatus).

Leukocyte profiles are broadly used to assess the health status of many species. Reference intervals, and an understanding of the factors that may influence these intervals, are necessary for adequate interpretation of leukograms. Using a data set that spans over three decades, we investigated variation in leukocyte profile in several populations of the evolutionarily unique reptile, the tuatara (Sphenodon punctatus).

16S rRNA gene-based meta-analysis of the reptile gut microbiota reveals environmental effects, host influences and a limited core microbiota.

An animal's gut microbiota plays an important role in host health, reproduction and digestion. However, many studies focus on only a few individuals or a single species, limiting our ability to recognize emergent patterns across a wider taxonomic grouping. Here, we compiled and reanalysed published 16S rRNA gene sequence data for 745 gut microbiota samples from 91 reptile species using a uniform bioinformatics pipeline to draw broader conclusions about the taxonomy of the reptile gut microbiota and the forces shaping it.

Characterization of sperm and implications for male fertility in the last of the Rhynchocephalians.

Managing a species of conservation concern can be best achieved when there is information on the reproductive physiology of both sexes available; however, many species lack this critical, baseline information. One such species, the tuatara (), is the last surviving member of one of the four reptile orders (Rhynchocephalia) and is the only reptile known to lack a male intromittent organ. Culturally and evolutionarily significant, the conservation of this species is a global priority for the maintenance of biodiversity.

Investigating the link between morphological characteristics and diet in an island population of omnivorous reptiles (Sphenodon punctatus).

The morphological characteristics that impact feeding ecology in ectotherms, particularly reptiles, are poorly understood. We used morphometric measures and stable isotope analysis (carbon-13 and nitrogen-15) to assess the link between diet and functional morphology in an island population of an evolutionarily unique reptile, the tuatara (Sphenodon punctatus). First, we established a significant positive correlation between overall body size, gape size, and fat store in tuatara (n=56).

Initial collection, characterization, and storage of tuatara (Sphenodon punctatus) sperm offers insight into their unique reproductive system.

Successful reproduction is critical to the persistence of at-risk species; however, reproductive characteristics are understudied in many wild species. New Zealand's endemic tuatara (Sphenodon punctatus), the sole surviving member of the reptile order Rhynchocephalia, is restricted to 10% of its historic range. To complement ongoing conservation efforts, we collected and characterized mature sperm from male tuatara for the first time.

Publisher Correction: The tuatara genome reveals ancient features of amniote evolution.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The tuatara genome reveals ancient features of amniote evolution.

The tuatara (Sphenodon punctatus)-the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana-is an iconic species that is endemic to New Zealand. A key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes. Here we analyse the genome of the tuatara, which-at approximately 5 Gb-is among the largest of the vertebrate genomes yet assembled.

Estimating the biodiversity of terrestrial invertebrates on a forested island using DNA barcodes and metabarcoding data.

Invertebrates are a major component of terrestrial ecosystems, however, estimating their biodiversity is challenging. We compiled an inventory of invertebrate biodiversity along an elevation gradient on the temperate forested island of Hauturu, New Zealand, by DNA barcoding of specimens obtained from leaf litter samples and pitfall traps. We compared the barcodes and biodiversity estimates from this data set with those from a parallel DNA metabarcoding analysis of soil from the same locations, and with pre-existing sequences in reference databases, before exploring the use of combined data sets as a basis for estimating total invertebrate biodiversity.

Behavioral variation in nesting phenology may offset sex-ratio bias in tuatara.

The nest environment for eggs of reptiles has lifelong implications for offspring performance and success, and, ultimately, for population viability and species distributions. However, understanding the various abiotic and biotic drivers of nesting is complex, particularly regarding variation in nesting behavior of females and consequences for sex ratios in species with temperature-dependent sex determination (TSD). We investigated how nest construction and nesting phenology affect the incubation environment of a reptile with TSD, the tuatara (Sphenodon punctatus), a species that is at risk from climate-mediated male bias in population sex ratios.

Thermoregulation of a temperate reptile in a forested habitat.

A major focus in zoology is to understand the phenotypic responses of animals to environmental variation. This is particularly important when dealing with ectotherms in a thermally heterogenous environment. We measured body temperatures of a free-ranging, medium sized temperate reptile, the tuatara, Sphenodon punctatus, to investigate its thermal opportunities and the degree to which the animal actively regulates its body temperature.

Temperature selection by juvenile tuatara (Sphenodon punctatus) is not influenced by temperatures experienced as embryos.

Most reptiles thermoregulate to achieve body temperatures needed for biological processes, such as digestion and growth. Temperatures experienced during embryogenesis may also influence post-hatching growth rate, potentially through influencing post-hatching choice of temperatures. We investigated in laboratory settings whether embryonic temperatures (constant 18°C, 21°C and 22°C) influence selected body temperatures (T) of juvenile tuatara (Sphenodon punctatus), providing a possible mechanism for differences in growth rates.

Cryptic inbreeding depression in a growing population of a long-lived species.

Genetic effects are often overlooked in endangered species monitoring, and populations showing positive growth are often assumed to be secure. However, the continued reproductive success of a few individuals may mask issues such as inbreeding depression, especially in long-lived species. Here, we test for inbreeding depression in little spotted kiwi (Apteryx owenii) by comparing a population founded with two birds to one founded with 40 birds, both from the same source population and both showing positive population growth.

The effect of two glyphosate formulations on a small, diurnal lizard (Oligosoma polychroma).

Formulations of glyphosate-based herbicides continue to dominate the global herbicide market, while there continue to be concerns regarding the impact of this herbicide on non-target organisms. Research also indicates that the additives within certain glyphosate formulations, such as surfactants, are actually more toxic than the glyphosate active ingredient alone. Concerns arise in particular when glyphosate formulations are proposed for vegetation control in areas inhabited by rare or threatened species.

Microbial Genomics of a Host-Associated Commensal Bacterium in Fragmented Populations of Endangered Takahe.

Isolation of wildlife into fragmented populations as a consequence of anthropogenic-mediated environmental change may alter host-pathogen relationships. Our understanding of some of the epidemiological features of infectious disease in vulnerable populations can be enhanced by the use of commensal bacteria as a proxy for invasive pathogens in natural ecosystems. The distinctive population structure of a well-described meta-population of a New Zealand endangered flightless bird, the takahe (Porphyrio hochstetteri), provided a unique opportunity to investigate the influence of host isolation on enteric microbial diversity.

Glucocorticoids in tuatara (Sphenodon punctatus): Some influential factors, and applications in conservation management.

Glucocorticoid (GC) hormones promote basic life processes, regulate life-history transitions, and help individuals cope with challenges and stressors, thereby playing an important fitness role. Here, we review recent evidence for several factors that influence plasma concentrations of corticosterone (CORT), the main GC in tuatara (Sphenodon punctatus), and discuss the application of CORT as a physiological tool to monitor conservation efforts. Observational studies show an association between CORT concentrations and seasonal reproductive activity, ambient temperature, and ecological habitat parameters (including presence of rats/seabird abundance, sex-ratio, and genetic diversity), and experimental studies show a positive influence of acute temperature increase on the CORT response.

Evaluating a multigene environmental DNA approach for biodiversity assessment.

Background: There is an increasing demand for rapid biodiversity assessment tools that have a broad taxonomic coverage. Here we evaluate a suite of environmental DNA (eDNA) markers coupled with next generation sequencing (NGS) that span the tree of life, comparing them with traditional biodiversity monitoring tools within ten 20×20 meter plots along a 700 meter elevational gradient.

Results: From six eDNA datasets (one from each of 16S, 18S, ITS, trnL and two from COI) we identified sequences from 109 NCBI taxonomy-defined phyla or equivalent, ranging from 31 to 60 for a given eDNA marker.

Presence of antibodies to Salmonella in tuatara (Sphenodon punctatus) sera.

Colonisation of a host by pathogenic microorganisms is a near constant threat to the health of all vertebrates and most species have evolved an efficient adaptive immune response which produces antibodies following exposure to a specific antigen. The strength of this response can be influenced by many factors including sex and season. Tuatara are exposed to Salmonella through contact with infected skinks and soil; however, no gastrointestinal colonisation of tuatara with Salmonella has been found.

Using a common commensal bacterium in endangered Takahe as a model to explore pathogen dynamics in isolated wildlife populations.

Predicting and preventing outbreaks of infectious disease in endangered wildlife is problematic without an understanding of the biotic and abiotic factors that influence pathogen transmission and the genetic variation of microorganisms within and between these highly modified host communities. We used a common commensal bacterium, Campylobacter spp., in endangered Takahe (Porphyrio hochstetteri) populations to develop a model with which to study pathogen dynamics in isolated wildlife populations connected through ongoing translocations.

Moving house: long-term dynamics of corticosterone secretion are unaltered in translocated populations of a rare reptile (the tuatara, Sphenodon punctatus).

Translocations are an important conservation tool used to restore at-risk species to their historical range. Unavoidable procedures during translocations, such as habitat disturbance, capture, handling, processing, captivity, transport and release to a novel environment, have the potential to be stressful for most species. In this study, we examined acute and chronic stress (through the measurement of the glucocorticoid corticosterone) in a rare reptile (the tuatara, Sphenodon punctatus).

Reptile reservoirs and seasonal variation in the environmental presence of Salmonella in an island ecosystem, Stephens Island, New Zealand.

A wide variety of Salmonella serotypes occurs within reptilian hosts, but their ecology is poorly understood. We collected cloacal swabs from tuatara (Sphenodon punctatus), fairy prions (Pachyptila turtur), and skinks (Oligosoma spp.) on Stephens Island, New Zealand, to screen for Salmonella.