Non-monotonicity check graphs

This file shows the graphs corresponding to the checks for non-monotonicity for the publication by Parker et al., \"Poaching of African elephant indirectly decreases population growth through lowered orphan survival\" published in Current Biology in 2021. The summary for this publication is as follows: Prolonged maternal care is vital to the well-being of many long-lived mammals (Clutton-Brock, 1991). The premature loss of maternal care, i.e. orphaning, can reduce offspring survival even after weaning is complete (Watts et al., 2009; Foster et al., 2012; Andres et al., 2013; Stanton et al., 2020). However, ecologists have not explicitly assessed how orphaning impacts population growth. We examined the impact of orphaning on population growth in a free ranging African elephant population, using 19 years of individual-based demographic monitoring data. We compared orphan and nonorphan survival, performed a sensitivity analysis to understand how population growth responds to the probability of being orphaned and orphan survival, and investigated how sensitivity to these orphan parameters changed with level of poaching. Orphans were found to have lower survival compared to nonorphaned age mates, and population growth rate was negatively correlated with orphaning probability and positively correlated with orphan survival. This demonstrates that, in addition to its direct effects, adult elephant death indirectly decreases population growth through orphaning. Population growth rate’s sensitivity to orphan survival increased for the analysis parameterized using only data from years of more poaching, indicating orphan survival is more important for population growth as orphaning increases. We conclude that orphaning substantively decreases population growth for elephants and should not be overlooked when quantifying the impacts of poaching. Moreover, we conclude that population models characterizing systems with extensive parental care benefit from explicitly incorporating orphan stages, and encourage research into quantifying effects of orphaning in other social mammals of conservation concern.

本文件配套展示的是2021年发表于《当代生物学（Current Biology）》的Parker等人的论文《盗猎非洲象通过降低孤儿象存活率间接抑制种群增长（Poaching of African elephant indirectly decreases population growth through lowered orphan survival）》的非单调性检验相关图表。该论文的研究摘要如下：长期的母育抚育对诸多长寿哺乳动物的生存繁衍至关重要（Clutton-Brock，1991）。幼崽在断奶完成后，若过早失去母育抚育（即成为孤儿），其存活率仍会下降（Watts等人，2009；Foster等人，2012；Andres等人，2013；Stanton等人，2020）。然而，生态学家尚未明确评估幼崽成为孤儿这一情况对种群增长的影响。我们基于19年的个体水平种群监测数据，对野外自由活动的非洲象种群中孤儿状况对种群增长的影响展开了研究。我们对比了孤儿象与非孤儿象的存活率，开展了敏感性分析以探明种群增长对成为孤儿的概率以及孤儿存活率的响应规律，并探究了对这些孤儿相关参数的敏感性如何随盗猎强度变化。研究发现，与同龄非孤儿象相比，孤儿象的存活率更低；种群增长率与成为孤儿的概率呈负相关，与孤儿存活率呈正相关。这表明，成年象死亡除了会产生直接影响外，还会通过导致幼崽成为孤儿的方式间接抑制种群增长。在仅使用高盗猎压力年份的数据进行参数化分析时，种群增长率对孤儿存活率的敏感性有所提升，这说明随着孤儿现象愈发普遍，孤儿存活率对种群增长的重要性也随之提升。我们的研究结论为：孤儿现象会显著降低大象的种群增长速率，在评估盗猎的影响时不应忽视这一因素。此外，我们认为，针对存在长期育幼行为的物种构建种群模型时，若明确纳入孤儿阶段将能提升模型的适用性；同时我们呼吁学界开展相关研究，量化孤儿现象对其他具有保护价值的群居哺乳动物的影响。