Heat tolerance at the immobile embryonic stage is expected to be critical in determining species vulnerability to climate change. However, how the mean and developmental plasticity of embryonic heat ...tolerance vary geographically, and how these geographic variations affect species' vulnerability under climate change remain unknown. We experimentally determined the mean and developmental plasticity of embryonic acute heat tolerance (EAHT, i.e., heat shock temperature at which embryonic heartbeats ceased) for three latitudinally distributed populations of an oviparous lacertid lizard. The experimental results suggested that the mean EAHT decreased with decreasing latitude and that the reaction norms of EAHT in relation to developmental temperatures showed "flat," "bell-shaped," and "decreasing" patterns at high, medium, and low latitudes, respectively. Based on the means and plasticity of EAHT and weather data across China, we project that the heat stress frequency would increase from the present to the future and increase toward low latitudes. Furthermore, heat stress becomes more extensive with the incorporation of developmental plasticity. Incorporating the mean EAHT during the embryonic development season, heat stress frequency, and climate variables in a species distribution model projects that suitable habitats could move northward in response to ongoing climate change and shrink due to the loss of southern habitat. More-over, even lizards within the areas that are predicted to remain highly suitable are expected to experience increases in heat stress over time, particularly at medium and low latitudes. Our study reveals geographic variation in the mean and developmental plasticity of EAHT and highlights its importance for predicting species vulnerability and range shifts in response to climate change.
Ongoing climate change has profoundly affected global biodiversity, but its impacts on populations across elevations remain understudied. Using mechanistic niche models incorporating species traits, ...we predicted ecophysiological responses (activity times, oxygen consumption and evaporative water loss) for lizard populations at high‐elevation (<3600 m asl) and extra‐high‐elevation (≥3600 m asl) under recent (1970–2000) and future (2081–2100) climates. Compared with their high‐elevation counterparts, lizards from extra‐high‐elevation are predicted to experience a greater increase in activity time and oxygen consumption. By integrating these ecophysiological responses into hybrid species distribution models (HSDMs), we were able to make the following predictions under two warming scenarios (SSP1‐2.6, SSP5‐8.5). By 2081–2100, we predict that lizards at both high‐ and extra‐high‐elevation will shift upslope; lizards at extra‐high‐elevation will gain more and lose less habitat than will their high‐elevation congeners. We therefore advocate the conservation of high‐elevation species in the context of climate change, especially for those populations living close to their lower elevational range limits. In addition, by comparing the results from HSDMs and traditional species distribution models, we highlight the importance of considering intraspecific variation and local adaptation in physiological traits along elevational gradients when forecasting species' future distributions under climate change.
Compared with their high‐elevation (<3600 m asl) counterparts, lizards from extra‐high‐elevation (≥3600 m asl) are predicted to experience a greater increase in activity time and oxygen consumption by 2081–2100, and we predict that lizards at both high‐ and extra‐high‐elevation will shift upslope; lizards at extra‐high‐elevation will gain more and lose less habitat than will their high‐elevation congeners. We therefore advocate the conservation of high‐elevation species in the context of climate change, especially for those populations living close to their lower elevational range limits.
Aim
Two of the most important forces affecting biodiversity are land use change (LUC) and global climate change (GCC). Previous studies have modelled their impacts on species separately, and ...together, but few have done so for multiple species with dispersal limitations incorporated into the models.
Location
Qinghai–Tibet plateau region.
Methods
We integrate species distribution models plus a dispersal model to predict LUC and GCC impacts on the ranges of five species of pikas in the Qinghai–Tibet plateau region of China. Pikas are sensitive to land use and climate change and have limited dispersal abilities.
Results
The predicted impacts of LUC and GCC on pikas vary between species as well as between LUC and GCC projections. Incorporation of dispersal limitations appreciably restricts the amount of colonized habitat. For all five species, the amount of habitat abandoned or colonized when LUC and GCC are modelled together is less than the sum of LUC and GCC modelled separately. Three of the five species experience a net increase in occupied habitat by 2080 relative to their current ranges under all modelled projections. However, relative to a “Dispersal Only” baseline scenario that assumes no environmental change but continued range expansion into suitable, unoccupied habitat, all five species suffer a net loss of occupied habitat by 2080 under some or all projections.
Main conclusions
Predictions of future distributions of species based solely on LUC or GCC, as well as predictions assuming additive impacts, can be misleading. Inclusion of dispersal limitations in models markedly alters predicted future distributions of species. The use of a “Dispersal Only” scenario provides a different and perhaps more accurate way to gauge net impacts to species. Future work should consider incorporating all these parameters to better predict the impacts of LUC and GCC on biodiversity.
Survival of the immobile embryo in response to rising temperature is important to determine a species’ vulnerability to climate change. However, the collective effects of 2 key thermal ...characteristics associated with climate change (i.e., rising average temperature and acute heat events) on embryonic survival remain largely unexplored. We used empirical measurements and niche modeling to investigate how chronic and acute heat stress independently and collectively influence the embryonic survival of lizards across latitudes. We collected and bred lizards from 5 latitudes and incubated their eggs across a range of temperatures to quantify population‐specific responses to chronic and acute heat stress. Using an embryonic development model parameterized with measured embryonic heat tolerances, we further identified a collective impact of embryonic chronic and acute heat tolerances on embryonic survival. We also incorporated embryonic chronic and acute heat tolerance in hybrid species distribution models to determine species’ range shifts under climate change. Embryos’ tolerance of chronic heat (T‐chronic) remained consistent across latitudes, whereas their tolerance of acute heat (T‐acute) was higher at high latitudes than at low latitudes. Tolerance of acute heat exerted a more pronounced influence than tolerance of chronic heat. In species distribution models, climate change led to the most significant habitat loss for each population and species in its low‐latitude distribution. Consequently, habitat for populations across all latitudes will shift toward high latitudes. Our study also highlights the importance of considering embryonic survival under chronic and acute heat stresses to predict species’ vulnerability to climate change.
Efectos colectivos del aumento de las temperaturas promedio y los eventos de calor en embriones ovíparos
Resumen
La supervivencia de los embriones inmóviles en respuesta al incremento de temperatura es importante para determinar la vulnerabilidad de las especies al cambio climático. Sin embargo, los efectos colectivos de dos características térmicas claves asociadas con el cambio climático (i. e., aumento de temperatura promedio y eventos de calor agudo) sobre la supervivencia embrionaria permanecen en gran parte inexplorados. Utilizamos mediciones empíricas y modelos de nicho para investigar cómo el estrés térmico crónico y agudo influye de forma independiente y colectiva en la supervivencia embrionaria de los lagartos en todas las latitudes. Recolectamos y criamos lagartos de cinco latitudes e incubamos sus huevos en un rango de temperaturas para cuantificar las respuestas específicas de la población al estrés por calor crónico y agudo. Posteriormente, mediante un modelo de desarrollo embrionario parametrizado con mediciones de tolerancia embrionaria al calor, identificamos un impacto colectivo de las tolerancias embrionarias al calor agudo y crónico en la supervivencia embrionaria. También incorporamos la tolerancia embrionaria crónica y aguda al calor en modelos de distribución de especies híbridas para determinar los cambios de distribución de las especies bajo el cambio climático. La tolerancia embrionaria al calor crónico (T‐crónico) permaneció constante, mientras que la tolerancia al calor agudo (T‐agudo) fue mayor en latitudes altas que en latitudes bajas. La tolerancia al calor agudo ejerció una influencia más pronunciada que la tolerancia al calor crónico. En los modelos de distribución de especies, el cambio climático provocó la pérdida de hábitat más significativa para cada población y especie en su distribución de latitudes bajas. En consecuencia, el hábitat para poblaciones en todas las latitudes se desplazará a latitudes altas. Nuestro estudio también resalta la importancia de considerar la supervivencia embrionaria bajo estrés térmico crónico y agudo para predecir la vulnerabilidad de las especies al cambio climático.
摘要
动物胚胎在面对温度升高时的存活率对于确定气候变化下物种的脆弱性至关重要。然而, 与气候变化相关的两个关键温度特征(即平均气温升高和极端高温事件)对胚胎存活的整合影响仍然存在诸多未知。我们利用实验测定和生态位建模相结合的方式探究了慢性和急性热压力如何独立和共同影响不同纬度的蜥蜴胚胎存活率。我们从五个纬度采集并繁殖蜥蜴, 并在一定温度范围内孵化其受精卵以测定各个种群对慢性和急性热压力的耐受响应。我们根据测定的胚胎耐热特征构建胚胎发育模型, 进一步确定了胚胎的慢性和急性高温耐受对胚胎存活的整合影响。最后, 我们将胚胎的慢性和急性高温耐受纳入混合物种分布模型, 以确定未来气候变化对物种分布范围的影响。结果表明, 胚胎对慢性高温的耐受能力在不同纬度保持一致, 而对极端高温事件的耐受能力随纬度升高而增强。在决定胚胎存活时, 急性高温耐受能力比慢性高温耐受能力具有更显著的作用。在气候变化的影响下, 各种群或物种在其各自低纬度分布区的栖息地丧失最为严重, 所有纬度的蜥蜴种群或物种的适宜栖息地都将向高纬度方向转移。本研究强调了考虑胚胎在慢性和急性热压力下的存活对预测气候变化下物种脆弱性的重要性。
The world's warm deserts are predicted to experience disproportionately large temperature increases due to climate change, yet the impacts on global desert biodiversity remain poorly understood. ...Because species in warm deserts live close to their physiological limits, additional warming may induce local extinctions. Here, we combine climate change projections with biophysical models and species distributions to predict physiological impacts of climate change on desert birds globally. Our results show heterogeneous impacts between and within warm deserts. Moreover, spatial patterns of physiological impacts do not simply mirror air temperature changes. Climate change refugia, defined as warm desert areas with high avian diversity and low predicted physiological impacts, are predicted to persist in varying extents in different desert realms. Only a small proportion (<20%) of refugia fall within existing protected areas. Our analysis highlights the need to increase protection of refugial areas within the world's warm deserts to protect species from climate change.
Abstract
The purging of deleterious alleles has been hypothesized to mitigate inbreeding depression, but its effectiveness in endangered species remains debatable. To understand how deleterious ...alleles are purged during population contractions, we analyzed genomes of the endangered Chinese crocodile lizard (Shinisaurus crocodilurus), which is the only surviving species of its family and currently isolated into small populations. Population genomic analyses revealed four genetically distinct conservation units and sharp declines in both effective population size and genetic diversity. By comparing the relative genetic load across populations and conducting genomic simulations, we discovered that seriously deleterious alleles were effectively purged during population contractions in this relict species, although inbreeding generally enhanced the genetic burden. However, despite with the initial purging, our simulations also predicted that seriously deleterious alleles will gradually accumulate under prolonged bottlenecking. Therefore, we emphasize the importance of maintaining a minimum population capacity and increasing the functional genetic diversity in conservation efforts to preserve populations of the crocodile lizard and other endangered species.
Montane reptiles are predicted to move to higher elevations in response to climate warming. However, whether upwards-shifting reptiles will be physiologically constrained by hypoxia at higher ...elevations remains unknown. We investigated the effects of hypoxic conditions on preferred body temperatures (T
) and thermal tolerance capacity of a montane lizard (
) from two populations on the Qinghai-Tibet Plateau. Lizards from 2600 m a.s.l. were exposed to O
levels mimicking those at 2600 m (control) and 3600 m (hypoxia treatment). Lizards from 3600 m a.s.l. were exposed to O
levels mimicking those at 3600 m (control) and 4600 m (hypoxia treatment). The T
did not differ between the control and hypoxia treatments in lizards from 2600 m. However, lizards from 3600 m selected lower body temperatures when exposed to the hypoxia treatment mimicking the O
level at 4600 m. Additionally, the hypoxia treatment induced lower critical thermal minimum (CT
) in lizards from both populations, but did not affect the critical thermal maximum (CT
) in either population. Our results imply that upwards-shifting reptiles may be constrained by hypoxia if a decrease in T
reduces thermally dependent fitness traits, despite no observed effect on their heat tolerance.
Nature reserves play an extraordinarily important role in conserving animal populations and their habitats. However, landscape change and unreasonable zoning designations often render these protected ...areas inadequate. Therefore, regular evaluation of the efficacy of protected lands is critical for maintaining and improving management strategies. Using species distribution models and GAP analysis, we assessed the changes in suitable habitat for the Brown Eared-pheasant (Crossoptilon mantchuricum) in two Chinese nature reserves between 1995 and 2013. Our results showed that the habitat suitability of Brown Eared-pheasant has changed dramatically during this period, and fragmentation analyses showed an increase in concentration area and decrease in patch area. In particular, our findings show that the national nature reserves need to adjust their ranges to ensure the conservation of this flagship species. Our study further provides a new viewpoint for evaluating the efficacy of protected lands, particularly in highly urbanized regions where conservation goals must be balanced with changing landscapes.
Zoning is an effective way to achieve regional planning and construction as well as standardized management. Efficient management zone designations would contribute to strengthening endangered ...species and biodiversity conservation of nature reserves. We evaluated the conservation effectiveness of the Baihuashan National Nature Reserve (BNNR), which was established primarily to conserve the vulnerable Brown Eared-Pheasant (Crossoptilon mantchuricum). We used species distribution models (SDMs) and GAP analysis to assess that the suitability of current functional zoning efforts to the protection of this species. Our results showed that current functional zoning is not adequate for protecting the Brown Eared-pheasant in BNNR. To optimize the conservation effectiveness for this species, we recommend a new functional zoning strategy be employed at BNNR, which is based on the distribution of the Brown Eared-pheasant and on the local economy. Our study thus provides a new strategy for optimizing the conservation effectiveness of functional zoning in nature reserves.
•Zoning is an effective way to achieve regional planning and construction as well as standardized management.•The current functional zoning within the BNNR is sub-optimal for the protection of Brown-Eared-pheasant.•As the zonation of nature reserves can be influenced by diverse factors, we suggest the zonation should consider the influence of multiple protected objects and other factors.
PDF
