Correlates of extinction risk in squamate reptiles: the relative importance of biology, geography, threat and range size

Abstract China is a country with one of the most species rich reptile faunas in the world. However, nearly a quarter of Chinese lizard species assessed by the China Biodiversity Red List are threatened. Nevertheless, to date, no study has explicitly examined the pattern and processes of extinction and threat in Chinese lizards. In this study, we conducted the first comparative phylogenetic analysis of extinction risk in Chinese lizards. We addressed the following three questions: 1) What is the pattern of extinction and threat in Chinese lizards? 2) Which species traits and extrinsic factors are related to their extinction risk? 3) How can we protect Chinese lizards based on our results? We collected data on ten species traits (body size, clutch size, geographic range size, activity time, reproductive mode, habitat specialization, habitat use, leg development, maximum elevation, and elevation range) and seven extrinsic factors (mean annual precipitation, mean annual temperature, mean annual solar insolation, normalized difference vegetation index (NDVI), human footprint, human population density, and human exploitation). After phylogenetic correction, these variables were used separately and in combination to assess their associations with extinction risk. We found that Chinese lizards with small geographic range, large body size, high habitat specialization, and living in high precipitation areas were vulnerable to extinction. Conservation priority should thus be given to species with the above extinction-prone traits so as to effectively protect Chinese lizards. Preventing future habitat destruction should also be a primary focus of management efforts because species with small range size and high habitat specialization are particularly vulnerable to habitat loss.

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The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽

10.1017/pab.2020.52 ◽

2020 ◽

pp. 1-14

Author(s):

Michelle M. Casey ◽

Erin E. Saupe ◽

Bruce S. Lieberman

Keyword(s):

North American ◽

Fossil Record ◽

Extinction Risk ◽

Geographic Range ◽

Range Size ◽

Late Paleozoic ◽

The North ◽

Geographic Range Size ◽

The Relationship ◽

Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

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Sexual selection, range size and population size

Ornis Hungarica ◽

10.2478/orhu-2013-0001 ◽

2012 ◽

Vol 20 (1) ◽

pp. 1-25 ◽

Cited By ~ 1

Author(s):

Anders Pape Møller ◽

László Zsolt Garamszegi

Keyword(s):

Sexual Selection ◽

Population Size ◽

Extinction Risk ◽

Range Size ◽

Sexual Dichromatism ◽

Common Descent ◽

Distribution Limits ◽

Western Palaearctic ◽

Linear Contrasts ◽

Average Fitness

Abstract Sexual selection may impose fitness costs on both males and females due to the costs of developing and maintaining exaggerated sexual signals, reducing average fitness in strongly sexually selected species. Such reductions in average fitness could affect local extinction risk and hence distribution range. However, given that both sexually monochromatic and dichromatic species are common and widespread, benefits of sexual selection must be invoked to maintain equilibrium. We tested for differences in breeding range size and population size between monochromatic and dichromatic species of birds in a comparative analysis of species from the Western Palaearctic. In an analysis of standardized linear contrasts of the relationship between sexual dichromatism and range size and population size, respectively, that controlled for similarity among taxa due to common descent, we found no significant relationship. However, when we analyzed carotenoid-based sexual dichromatism sexually dichromatic species had larger distribution areas and higher northernmost distribution limits, but not southernmost distribution limits than sexually monochromatic species. In contrast, melanin-based sexual dichromatism was not significantly associated with range size or population size. Therefore, population density of sexually dichromatic species with carotenoid-based coloration was lower than that of monochromatic species, because dichromatic species had similar population sizes but larger ranges than monochromatic species. These findings suggest that the different physiological roles of pigments associated with sexual dichromatism have effects on total range size of birds.

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Geographic range size and extinction risk assessment in nomadic species

Conservation Biology ◽

10.1111/cobi.12440 ◽

2015 ◽

Vol 29 (3) ◽

pp. 865-876 ◽

Cited By ~ 38

Author(s):

Claire A. Runge ◽

Ayesha Tulloch ◽

Edd Hammill ◽

Hugh P. Possingham ◽

Richard A. Fuller

Keyword(s):

Risk Assessment ◽

Extinction Risk ◽

Geographic Range ◽

Range Size ◽

Geographic Range Size ◽

Extinction Risk Assessment

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Modeling contemporary range size patterns of endemic birds in China: Testing the relative importance of phylogeny, space, and environment

Journal of Asia-Pacific Biodiversity ◽

10.1016/j.japb.2014.05.002 ◽

2014 ◽

Vol 7 (3) ◽

pp. 229-232

Author(s):

Youhua Chen

Keyword(s):

Range Size ◽

Relative Importance ◽

Endemic Birds

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Extinction risk is most acute for the world’s largest and smallest vertebrates

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1702078114 ◽

2017 ◽

Vol 114 (40) ◽

pp. 10678-10683 ◽

Cited By ~ 89

Author(s):

William J. Ripple ◽

Christopher Wolf ◽

Thomas M. Newsome ◽

Michael Hoffmann ◽

Aaron J. Wirsing ◽

...

Keyword(s):

Body Mass ◽

Extinction Risk ◽

Anthropogenic Activities ◽

Large Body ◽

Range Size ◽

Bony Fishes ◽

Cartilaginous Fishes ◽

Direct Killing ◽

Negative Relationships ◽

Insight Into

Extinction risk in vertebrates has been linked to large body size, but this putative relationship has only been explored for select taxa, with variable results. Using a newly assembled and taxonomically expansive database, we analyzed the relationships between extinction risk and body mass (27,647 species) and between extinction risk and range size (21,294 species) for vertebrates across six main classes. We found that the probability of being threatened was positively and significantly related to body mass for birds, cartilaginous fishes, and mammals. Bimodal relationships were evident for amphibians, reptiles, and bony fishes. Most importantly, a bimodal relationship was found across all vertebrates such that extinction risk changes around a body mass breakpoint of 0.035 kg, indicating that the lightest and heaviest vertebrates have elevated extinction risk. We also found range size to be an important predictor of the probability of being threatened, with strong negative relationships across nearly all taxa. A review of the drivers of extinction risk revealed that the heaviest vertebrates are most threatened by direct killing by humans. By contrast, the lightest vertebrates are most threatened by habitat loss and modification stemming especially from pollution, agricultural cropping, and logging. Our results offer insight into halting the ongoing wave of vertebrate extinctions by revealing the vulnerability of large and small taxa, and identifying size-specific threats. Moreover, they indicate that, without intervention, anthropogenic activities will soon precipitate a double truncation of the size distribution of the world’s vertebrates, fundamentally reordering the structure of life on our planet.

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Coarse- and fine-scale patterns of distribution and habitat selection places an Amazonian floodplain curassow in double jeopardy

PeerJ ◽

10.7717/peerj.4617 ◽

2018 ◽

Vol 6 ◽

pp. e4617 ◽

Cited By ~ 1

Author(s):

Gabriel A. Leite ◽

Izeni P. Farias ◽

André L. S. Gonçalves ◽

Joseph E. Hawes ◽

Carlos A. Peres

Keyword(s):

Habitat Selection ◽

Home Range ◽

Extinction Risk ◽

Spatial Scales ◽

Habitat Preferences ◽

Open Water ◽

Home Range Size ◽

Range Size ◽

Conservation Strategy ◽

Fine Scale

Patterns of habitat selection are influenced by local productivity, resource availability, and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (Crax globulosa), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to white-water floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of C. globulosa using conventional VHF telemetry. To estimate patterns of habitat selection, we used geo-locations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood map of the study area. We captured two females and one male, which we monitored for 13 months between September 2014 and September 2015. Average home range size was 283 ha, based on the 95% aLoCoH estimator. Wattled Curassows selected areas of prolonged flood pulses (six to eight months/year) and had a consistent tendency to be near open water, usually in close proximity to river banks and lakes, especially during the dry season. Amazonian floodplains are densely settled, and the small portions of floodplain habitat used by Wattled Curassows are both the most accessible to hunters and most vulnerable to deforestation. As a result, the geographic and ecological distribution of Wattled Curassows places them at much higher extinction risk at multiple spatial scales, highlighting the need to consider habitat preferences within their conservation strategy.

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Correlates of extinction risk in Australian squamate reptiles

Journal of Biogeography ◽

10.1111/jbi.14140 ◽

2021 ◽

Author(s):

Anna F. Senior ◽

Monika Böhm ◽

Christopher P. Johnstone ◽

Matthew D. McGee ◽

Shai Meiri ◽

...

Keyword(s):

Extinction Risk ◽

Squamate Reptiles

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Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Journal of Mammalogy ◽

10.1093/jmammal/gyaa093 ◽

2020 ◽

Author(s):

Zhixin Wen ◽

Anderson Feijó ◽

Jilong Cheng ◽

Yuanbao Du ◽

Deyan Ge ◽

...

Keyword(s):

Body Mass ◽

Small Mammals ◽

Environmental Conditions ◽

Niche Breadth ◽

Interspecific Variation ◽

Range Size ◽

Relative Importance ◽

Elevational Gradients ◽

Negative Effect ◽

Elevational Range

Abstract Recent work on tropical montane small mammals and birds has shown that abundance–elevational range size relationships (i.e., the relationship between abundance of a species and its elevational range size) can be manifested in a number of distinct generalized patterns. To understand why different patterns occur, one first must understand the causal mechanisms behind patterns of interspecific variation in species abundance and elevational range size. Using small mammal data along five elevational gradients in Southwest China, we assessed the relative importance of body mass, niche position (i.e., how typical the environmental conditions in which a species occurs are of the full set of conditions under consideration) and niche breadth in explaining the interspecific variation in mean abundance of species of small mammals, and elevational range size. Niche position and niche breadth were calculated using outlying mean index analysis based on 24 environmental variables. The relative importance of body mass, niche position, and niche breadth, in explaining the mean abundance and elevational range size of species were examined using phylogenetic regression and phylogenetic path analyses. Along each of five elevational gradients, body mass maintained a nonsignificant (P > 0.05) relationship both with mean abundance and elevational range size when the effects of phylogeny were taken into account. Niche position had a negative effect on mean abundance and elevational range size (species with a niche position close to edge environmental conditions were rarer and had smaller elevational range sizes) across five gradients (significant negative effect: three gradients for mean abundance; five gradients for elevational range size). Conversely, a positive effect of niche breadth on mean abundance and elevational range size was observed consistently, yet the effect was significant only for some gradients (mean abundance: two gradients; elevational range size: four gradients). Our study suggests that niche position and niche breadth both are good predictors of abundance and elevational range size of montane small mammals; niche position and niche breadth therefore play a strong role in the formation of abundance–elevational range size relationship.

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