Cacti usually grow in areas with severe resource limitations, making them vulnerable to local extinction. To ensure their survival, cacti have evolved a differential allocation of resources that is reflected in trade-offs among vital rates. In this study, we assess the effect of interannual climatic variation on resource allocation to vital rates in a cactus with biogeographical rarity ( ssp. ). Eight-year observations were used to relate vital rates to climatic data using population projection matrix models and Spearman correlations. The finite rate of population growth (λ) indicates, on average, a population in equilibrium. The transition from seeds to seedlings and the growth of seedlings, juveniles, and adults are the stages of the lifecycle with the highest selection pressure, with adults and juveniles being the categories with the greatest contribution to λ. This species allocates more resources to survival than to growth or reproduction during its lifecycle. The trade-off between the survival of adult individuals and fertility seems more marked in years with higher rainfall and minimum temperature turned out to be a key factor for population maintenance. This research provides new insights into the strategies used by rare globose cacti to avoid extinction in these limiting environments.

中文翻译：

---

稀有仙人掌的权衡动态：适应度时间变化的人口统计后果是什么？

仙人掌通常生长在资源严重有限的地区，这使得它们很容易在当地灭绝。为了确保生存，仙人掌进化出了一种不同的资源分配方式，这反映在生命率之间的权衡上。在这项研究中，我们评估了年际气候变化对生物地理稀有仙人掌（ssp.）的生命率资源分配的影响。使用人口投影矩阵模型和斯皮尔曼相关性，使用八年的观察将生命率与气候数据联系起来。平均而言，有限的人口增长率 (λ) 表明人口处于均衡状态。从种子到幼苗的转变以及幼苗、幼苗和成虫的生长是生命周期中选择压力最高的阶段，其中成虫和幼苗对λ贡献最大。该物种在其生命周期中为生存分配的资源多于用于生长或繁殖的资源。在降雨量较高且最低气温较高的年份，成年个体的生存与生育力之间的权衡似乎更为明显，而最低气温却是维持种群数量的关键因素。这项研究为罕见的球形仙人掌在这些限制环境中避免灭绝的策略提供了新的见解。