The tuatara (Sphenodon punctatus)-the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana 1,2-is an iconic species that is endemic to New Zealand 2,3. 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 2,4. Here we analyse the genome of the tuatara, which-at approximately 5 Gb-is among the largest of the vertebrate genomes yet assembled. Our analyses of this genome, along with comparisons with other vertebrate genomes, reinforce the uniqueness of the tuatara. Phylogenetic analyses indicate that the tuatara lineage diverged from that of snakes and lizards around 250 million years ago. This lineage also shows moderate rates of molecular evolution, with instances of punctuated evolution. Our genome sequence analysis identifies expansions of proteins, non-protein-coding RNA families and repeat elements, the latter of which show an amalgam of reptilian and mammalian features. The sequencing of the tuatara genome provides a valuable resource for deep comparative analyses of tetrapods, as well as for tuatara biology and conservation. Our study also provides important insights into both the technical challenges and the cultural obligations that are associated with genome sequencing.
Our knowledge of the conservation status of reptiles, the most diverse class of terrestrial vertebrates, has improved dramatically over the past decade, but still lags behind that of the other tetrapod groups. Here, we conduct the first comprehensive evaluation (~92% of the world's ~1714 described species) of the conservation 1 Joint senior authors. D.G. Chapple et al.
A lthough islands cover only ~5% of the global land area, they support ~20% of terrestrial plant and vertebrate species (Courchamp et al. 2014). Insular species are particularly vulnerable to extinction; one-third of critically endangered species and nearly two-thirds of recent extinctions consisted of species endemic to islands (Tershy et al. 2015), and these declines may have impacts on Indigenous peoples (Lyver et al. 2019). Several interacting factors contribute to this vulnerability, including invasions by non-native species and habitat loss (Simberloff et al. 2013). Island ecosystems are particularly susceptible to multiple climate-change factors, including rising sea level and loss of suitable climatic conditions (Courchamp et al. 2014), but conservation and restoration efforts rarely account for such interacting drivers of change (Parmesan et al. 2013). Understanding the effects of climate change on island ecosystems necessitates knowing how climate interacts with other ecologically influential processes (eg habitat loss, land transformation, invasive species). Here, we use the example of New Zealand to highlight interactions between changing climate and other threats to biodiversity, and stress the need to collect and maintain long-term datasets to improve strategies to mitigate climate-change effects. Lessons learned from New Zealand are relevant to islands (and potentially continental systems) elsewhere (Simberloff 2019), particularly with respect to the indirect and interactive effects of climate-change impacts. Although we focus on land-based ecosystems, we note that warming seas and ocean acidification are affecting marine systems in New Zealand's territorial waters, as well as elsewhere. Finally, we emphasize the need to work with Indigenous communities to improve the effectiveness of mitigation and adaptation approaches. New Zealand (also known by the Indigenous name Aotearoa) consists of three main islands, along with hundreds of smaller islands in rivers, lakes, and harbors, as well
The urgency of predicting future impacts of environmental change on vulnerable populations is advancing the development of spatially explicit habitat models. Continental-scale climate and microclimate layers are now widely available. However, most terrestrial organisms exist within microclimate spaces that are very small, relative to the spatial resolution of those layers. We examined the effects of multi-resolution, multi-extent topographic and climate inputs on the accuracy of hourly soil temperature predictions for a small island, generated at a very high spatial resolution (<1 m 2 ) using the mechanistic microclimate model in NicheMapR. Achieving an accuracy comparable to lower-resolution, continentalscale microclimate layers (within about 2-3°C of observed values) required the use of daily weather data as well as high resolution topographic layers (elevation, slope, aspect, horizon angles), while inclusion of site-specific soil properties did not markedly improve predictions. Our results suggest that large-extent microclimate layers may not provide accurate estimates of microclimate conditions when the spatial extent of a habitat or other area of interest is similar to or smaller than the spatial resolution of the layers themselves. Thus, effort in sourcing model inputs should be focused on obtaining high resolution terrain data, e.g., via LiDAR or photogrammetry, and local weather information rather than in situ sampling of microclimate characteristics.
Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.
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