The global distribution of tetrapods reveals a need for targeted reptile conservation

Abstract

The distributions of amphibians, birds and mammals have underpinned global and local conservation priorities, and have been fundamental to our understanding of the determinants of global biodiversity. In contrast, the global distributions of reptiles, representing a third of terrestrial vertebrate diversity, have been unavailable. This prevented the incorporation of reptiles into conservation planning and biased our understanding of the underlying processes governing global vertebrate biodiversity. Here, we present and analyse the global distribution of 10,064 reptile species (99% of extant terrestrial species). We show that richness patterns of the other three tetrapod classes are good spatial surrogates for species richness of all reptiles combined and of snakes, but characterize diversity patterns of lizards and turtles poorly. Hotspots of total and endemic lizard richness overlap very little with those of other taxa. Moreover, existing protected areas, sites of biodiversity significance and global conservation schemes represent birds and mammals better than reptiles. We show that additional conservation actions are needed to effectively protect reptiles, particularly lizards and turtles. Adding reptile knowledge to a global complementarity conservation priority scheme identifies many locations that consequently become important. Notably, investing resources in some of the world’s arid, grassland and savannah habitats might be necessary to represent all terrestrial vertebrates efficiently

A biogeographic reversal in sexual size dimorphism along a continental temperature gradient

“…We found no relationship with precipitation seasonality, suggesting differences between dry and wet seasons are less important than temperature variation for sexual size dimorphism; this could be because lizards, in general (though there are exceptions), are able to effectively exploit dry environments (Roll et al 2017). We found no relationship with precipitation seasonality, suggesting differences between dry and wet seasons are less important than temperature variation for sexual size dimorphism; this could be because lizards, in general (though there are exceptions), are able to effectively exploit dry environments (Roll et al 2017).…”

“…All data used in this manuscript are available via Hijmans et al (2005), Roll et al (2017) and Meiri (2018). A list of species is given in Supplementary material Appendix 1 Table A7.…”

“…We test predictions of the reproductive selection hypotheses by evaluating the relationships between SSD, male and female size, clutch size and climate. Furthermore, males of many lizard species compete for mates and territories (Stamps 1983), their morphology (including size) has been linked to resource use, competition intensity, clutch size and reproductive output (Butler et al 2000, Meiri 2008, Losos 2009, Meiri et al 2012, Mesquita et al 2016, and they display a strong species richness gradient in North America (Currie 1991, Olalla-Tarraga et al 2006, Roll et al 2017). To address the potential scale dependence of the SSD-species richness relationship, we carry out our tests at three different sampling grains, with the expectation that patterns should emerge most strongly at finer grain sizes, that may better reflect the existence of sympatric competing species.…”

Alternative pathways to diversity across ecologically distinct lizard radiations

“…Some of the greatest diversity in lizards is present in the hot and dry deserts of southern Africa, the Arabian Peninsula and western Australia (Pianka, 1973;Roll et al, 2017), biomes relatively low in diversity of other vertebrates. Some of the greatest diversity in lizards is present in the hot and dry deserts of southern Africa, the Arabian Peninsula and western Australia (Pianka, 1973;Roll et al, 2017), biomes relatively low in diversity of other vertebrates.…”

Sunning themselves in heaps, knots, and snarls: The extraordinary abundance and demography of island watersnakes

“…The variation in annual survival revealed in our case study, and review suggests that demography may be unusually plastic in snakes compared to more frequently studied taxa. Our review reveals a strong bias favoring North American and temperate/subtropical species with few representatives from centers of snake diversity in the tropics (compare Figure 6 with figure 1d in Roll et al., 2017), thus much remains to be learned regarding snake demography. We suspect that, as additional studies accumulate, future analyses, which might also include juvenile survival, offspring size, offspring number, growth parameters, and generation time, will clarify ecological and evolutionary determinants of snake life history.…”