Data from: Land cover, individual's age and spatial sorting shape landscape resistance in the invasive frog Xenopus laevis

1. The description of functional connectivity is based on the quantification of landscape resistance, which represents species-specific movement costs across landscape features. Connectivity models use these costs to identify movement corridors at both individual and population levels and provide management recommendations for populations of conservation interest. Typically, resistance costs assigned to specific land cover types are assumed to be valid for all individuals of the population. Little attention has been paid to intraspecific variation in resistance costs due to age or dispersal syndrome, which may significantly affect model predictions. 2. We quantified resistance costs in an expanding invasive population of the African clawed frog Xenopus laevis in Western France. In this principally aquatic amphibian, juveniles, sub-adults and adults disperse overland. The enhancement of dispersal traits via spatial sorting has been also observed at the range periphery of the population. Resistance costs, and thus connectivity, might vary as a function of life stage and position within the invaded range. 3. We assessed multiple dimensions of functional connectivity. On various land cover types, we measured locomotion, as crossing speed, in different post-metamorphic age classes, and dehydration, sensitivity of locomotion to dehydration, and substrate preference in juveniles. We also tested the effect of the position in the invaded range (core vs. periphery) on individual performances. 4. In juveniles, general trends toward higher resistance costs on grass and lower resistance costs on bare soil and asphalt were observed, although not all experiments provided the same cost configurations. Resistance to locomotion varied between age classes, with adults and subadults facing lower costs than juveniles, particularly when crossing structurally complex land cover types like grass and leaf litter. The position in the range had a minor effect on landscape resistance, and only in the dehydration experiment, where water loss in juveniles was lower at the range periphery. 5. Depicting functional connectivity requires: i) assessing multiple dimensions of behavioural and physiological challenges faced by animals during movement; ii) considering factors, such as age and dispersal syndrome, that may affect movement at both individual and population level. Ignoring this complexity might generate unreliable connectivity models and provide unsupported management recommendations for conservation.

1. 功能连通性（functional connectivity）的描述基于景观阻力（landscape resistance）的量化，景观阻力表征物种在不同景观要素间运动的特异性成本。连通性模型借助此类成本，可在个体及种群层面识别运动廊道，并为具有保护价值的种群提供管理建议。通常而言，研究者默认分配给特定土地覆盖类型的阻力成本适用于种群内所有个体，但针对因年龄或扩散综合征导致的阻力成本种内变异的关注却极少，而这类变异可能会对模型预测结果产生显著影响。
2. 本研究针对法国西部一个处于扩张过程中的入侵种群——非洲爪蟾（Xenopus laevis），对其景观阻力成本进行了量化。作为以水生为主的两栖动物，非洲爪蟾的幼体、亚成体与成体均会进行陆地扩散。此前研究已在该种群的分布范围边缘观察到，空间分选作用会强化其扩散相关性状。因此，景观阻力成本乃至功能连通性，可能会随生活史阶段以及入侵范围中的位置差异而发生变化。
3. 本研究从多个维度对功能连通性进行了评估：针对多种土地覆盖类型，我们测定了不同变态后龄期个体的运动能力（以穿越速度为指标）；同时在幼体层面测定了脱水情况、运动能力对脱水的敏感性以及基质偏好。此外，我们还检验了入侵范围中的位置（核心区与边缘区）对个体表现的影响。
4. 在幼体实验中，尽管不同实验的阻力成本配置并不完全一致，但整体呈现出草地的阻力成本更高，裸土与沥青路面的阻力成本更低的趋势。不同龄期个体的运动阻力存在差异：成体与亚成体的运动成本低于幼体，尤其是在穿越草地、枯落物层等结构复杂的土地覆盖类型时。分布范围位置对景观阻力的影响较小，仅在脱水实验中观察到显著差异——边缘区幼体的水分流失量更低。
5. 要准确刻画功能连通性，需要做到两点：其一，评估动物在运动过程中面临的多维度行为与生理挑战；其二，考虑年龄、扩散综合征等可能在个体及种群层面影响运动能力的因素。若忽视这类复杂性，可能会生成不可靠的连通性模型，并为保护工作提供缺乏依据的管理建议。