In a recently published paper in Diversity and Distributions we try to illuminate aspects regarding the biology, and conservation of all narrow ranged lizard species, across the globe.
When exploring different attributes of small ranged species we found that most of them inhabit relatively inaccessible places in tropical climates worldwide. Furthermore, they are mostly small bodied species; many of them are active at night; and live in rocky habitats. Among the different lizard groups geckos and skinks dominate with many rare species.
This work could help better focus conservation efforts by pointing at the species, and places, that are in the greatest need of protection. Many of the species, especially those which have not been observed for decades, may well be already extinct. However, to-date only six of the species studied have been officially recognized as such. In order to examine the true extent of such extinctions, and try to prevent future ones, the study provides invaluable information for directing future research and conservation efforts.
In a recent publication in Global Ecology and Biogeography we explored the prevalence of nocturnality amongst Eurasian lizard species and tried to understand what drives these patterns.
Most animals – at least those that live above ground – are active either during the day or during the night. Being active at either time of day carries with it unique benefits and challenges, and thus particular adaptations. Because of this being nocturnal or diurnal is a trait that is pretty rigid amongst closely related species.
We found that nocturnal lizards have the highest species richness in the tropics and in deserts, and their richness decreases when they get closer to the North Pole. Nocturnal lizards are precluded altogether from the coldest regions inhabited by lizards – in high mountains and the highest latitudes.
Author: Enav Vidan
A short history of GARD and how it has been used to highlight gaps in global conservation priorities
In a paper published in Nature Ecology and Evolution we present the first global maps of all reptiles - and thus complete the global distributions of all tetrapods. We further explore how the new reptile information changes how we think about global conservation priorities. As this is the first place where all of the GARD maps have been used and published, we use this opportunity to share some of the history of GARD itself, as well as the particular work that was carried out for this paper.
The beginnings of GARD
Planning for reptile conservation globally we first needed to map the distribution of all known species. About 8500 of them when we started in 2006, about 10,500 now recognized. This was a time when such global databases were being published for amphibians, birds, and mammals – some of us have been instrumental in assembling those databases, so we felt fairly confident we knew how it should be done.
We finally had at least some data for all the species or reptiles we thought one could map about two year ago. Then we met again to start the immensely important process of reviewing the distribution data to ensure errors were kept to the minimum (a process that is still ongoing).
Do unique reptilian biologies and ecologies demand particular conservation needs?
Or in other words do the major global conservation priorities designations adequately represent reptiles or do their unique distributions make them less protected. It turns out that many reptiles – predominantly lizards and turtles are left out of global priority regions and protected areas.
Ecoregions that increase in importance for conservation, when reptile data are added (dark blue - top decile ecoregions, light blue - top quartile ecoregions)
Island life only works if you’re easy-going – uncovering predictions of the island syndrome for lizard clutch size variation
In a recent publication in the Journal of Biogeography we show that Insular lizards with variable clutch sizes follow the predictions of the island syndrome, while lizards with fixed clutches do not.
Author: Rachel Schwarz
The latitudinal diversity gradient and interspecific competition: no global relationship between lizard dietary niche breadth and species richness
In a 2017 publication in Global Ecology and Biogeography, we collated a novel quantitative volumetric dietary dataset for 308 lizard species worldwide from the field and literature. This novel dataset enabled us to test seven competing hypotheses posited to explain dietary niche breadth, focusing on those that are thought to either cause, or be influenced by, the latitudinal diversity gradient.
A major tenant explaining greater species richness in the tropics is interspecific competition. Dietary niche breadth has long been hypothesized to decrease from the poles toward the tropics, as the numbers of competitors increase. Geographical variation in niche breadth is also hypothesized to be linked to high ambient energy levels, water availability, productivity and climate stability – reflecting an increased number of available prey taxa. Range size and body size are also hypothesized to be strongly and positively associated with niche breadth. We sought to determine which of these factors is associated with geographical variation in niche breadth across broad spatial scales and thus potentially drive the latitudinal diversity gradient.
The synergistic effects of a narrow dietary niche and small range size augments the vulnerability of species to habitat loss and climate change. Based on our findings, the ‘competitionist’s paradigm’ seems to be the exception rather than the rule in explaining the latitudinal diversity gradient.
Author: Alison Gainsbury
When exploring the extinction of Late Quaternary reptiles it seems that body-size was an important predictor of extinction rate. Larger reptiles were more likely to go extinct - published now in Global Ecology and Biogeograpy.
The causes for these extinctions are numerous, and include over-harvesting by humans, introduction of invasive carnivores and rats, habitat change by human colonization, and possibly indirect cascade effects caused by the extinction of other, co-existing species. Our study helps us better understand the mechanisms of extinction in reptiles, and therefore might prove useful for pinpointing species which might be vulnerable to anthropogenic pressures in the future, and thus in need of conservation planning.
Author: Alex Slavenko
In our recent publication in the Journal of Biogeography, we assembled a comprehensive distribution map of all reptiles in Africa in order to quantify their geographical overlap with the other vertebrate groups, and to assess the environmental correlates underlying these patterns.
The latitudinal gradient of increasing biological diversity towards the equator is one of the best recognized patterns in biogeography, and has been acknowledged for some time. The naturalist, Alexander von Humboldt wrote of his travels over 200 hundred years ago, that as we approach the tropics, "the greater the variety of structure, form, colour, youth and vigor of organic life." A number of well-known hypotheses explaining this pervasive pattern of the increasing number of different species towards the equator have since proliferated. These include elevated ambient energy and precipitation, the number of different habitats or niches, higher plant productivity, and many more.
To create our geographic distribution map of reptiles in Africa, we obtained data from a variety of field-guides and atlases, museum databases, the primary literature, IUCN assessments, and maps based on expert knowledge of reptile species and the habitats they occupy. A challenging aspect of the project was to ensure that our maps remained current with respect to new species discoveries and taxonomic name changes (which are constantly being revised), and we also had to confirm the validity of type specimen identifications and localities, especially those referenced from obscure sources and archaic museum specimens. We used GIS software to digitize and overlay the maps of each individual African reptile species (1,601 species in total!) one on top of the other, which allowed us to count the number of species present in a given area - which we call “species richness”.
When we looked at which environmental predictors best explained these species richness maps we found that net primary productivity (the amount of photosynthetic activity by plants) and precipitation explain most of the variation in reptile and other vertebrates. This explains the clear latitudinal pattern seen in their respective maps, which reflects a strong correlation with plant productivity and rainfall as you move closer to the equator. But again, lizards are unique in that none of these environmental correlates explain their distributions. This is because lizards are well adapted to a wide range of habitats including the tropics as well as the harsh conditions of the desert where plant productivity and rainfall are low. We also showed that individual lizard species on average occupy smaller geographic distributions, reflecting their ability to occupy diverse niches.
Our findings that the distribution of lizard species in Africa is unique when compared to the other vertebrate groups now confirms a pattern that has been seen elsewhere in previous studies (i.e. Australia) and most recently by our paper on the global distribution of reptiles. This shows the importance of studying the diverse reptile groups distinctly instead of lumping them all together, and will have bearing on large-scale conservation efforts that do not represent all reptile groups.
Author: Amir Lewin
Here be dragons – how new digital tools aid in exploring humans’ perceptions towards reptiles, and their conservation
In an article published in Biological Conservation we tallied the number of page-views each reptile species’ page in all of Wikipedia language editions had during 2014. We further correlated these numbers with various other attributes of the reptiles.
There is a debate in conservation as to whether the fact that we as humans like a particular species justifies conserving it, regardless of its importance from an ecological point of view. But although this idea of some species being "culturally valuable" has been around for some time, it has been difficult to measure and define. Whether or not we want to take these cultural variables into account when shaping conservation policy, we need data to support those decisions. In our study we looked at 55.5 million page views in the year 2014 for all of the 10,002 species of reptile accessed in Wikipedia.
Among more traditional conservationists there may be the view that we shouldn't incorporate cultural values into decisions about policy or funding. However, the fact is that whether we like it or not, we already do – how much funding do lions get compared with, for example, a species of small snail that doesn't even have an English name, even if the snail is more at risk of going extinct? The biases are already there. There's also an argument that the traditional thinking around conservation hasn't quite worked, so we need to reframe our approach. Regardless of the point of view you take, having this sort of quantitative data is critical.
The findings of this article have been picked up by several news outlets such as The Guardian, Haaretz Daily Newspaper, as well as Mongabay, Oxford University news and many others.
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