Cascading extinctions due to loss of indirect ecological interactions

由于间接生态相互作用丧失而导致的级联灭绝

• 批准号: NE/K005650/1
• 负责人: Franciscus Van Veen
• 金额: $ 48.37万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK005650%2F1
• 关键词: Cascading; extinctions; due; loss; indirect

The current high rates of species extinctions are well publicised and it is clear that much of this is due to human activities such as overexploitation, habitat destruction and global environmental change due to greenhouse gas emissions. The loss of species is not just a moral and aesthetic issue. It has been demonstrated repeatedly that the ecosystem services (food production, soaking up of carbon emissions, pest control, flood control etc.) that human societies rely on are positively related to species diversity in ecosystems. The protection of biodiversity is therefore a major priority for governments. The effectiveness of this protection depends on how well we understand the processes that lead to species declines. Sometimes this is obvious: The collapse of cod stocks is clearly due to overfishing. Often however, such direct impacts are followed by secondary extinctions of other species, for not always obvious reasons, with the danger that this leads to a cascade of further extinctions and ecosystem collapse. Predicting these cascades is challenging and requires a detailed understanding of how the interconnectedness of species in ecosystems affects the transmission of human impacts on one species to other species that are not directly linked to it. This is particularly important for species at higher trophic levels (carnivores) which are most vulnerable to extinction. The idea has long existed that species of carnivore that specialise on different prey have positive effects on each other by limiting their prey populations and thereby preventing one prey species from outcompeting the other. A consequence of this is that if a carnivore is lost from the community, its prey is released from control and may subsequently out-compete the other prey species leaving the other carnivore without food and facing extinction. This is potentially an important mechanism by which extinction cascades occur, however, it is difficult to obtain experimental evidence for such effects. We have done preliminary experiments with simple insect communities in the laboratory which have demonstrated that the removal of one carnivore species does indeed lead to the extinction of others in just a few generations. The challenge now is to scale this model system up to a more realistic scale. We propose to carry out experiments in field-based mesocosms - roughly 2 meter cubed enclosures in which we can control the exact composition of the ecological community. We will assemble communities of insects in these and impose specific harvesting regimes on target species and follow the indirect impact this has on the other species and, in particular, whether the predicted extinction cascades occur. Within this setting we can manipulate important variables, such as the strength of competition among prey species, and test their impact on the outcome. We can also test the prediction that more species-rich and complex communities will be more resistant to extinction cascades, which would mean that as biodiversity is lost, the chance that further losses trigger extinction cascades increases.

目前物种灭绝率很高，这是众所周知的，很明显，这在很大程度上是由于人类活动，如过度开发，栖息地破坏和全球环境变化，由于温室气体排放。物种的消失不仅仅是一个道德和美学问题。事实一再表明，生态系统服务（粮食生产、吸收碳排放、虫害防治、防洪等）人类社会赖以生存的生态系统与生态系统中的物种多样性正相关。因此，保护生物多样性是各国政府的一个主要优先事项。这种保护的有效性取决于我们对导致物种减少的过程的理解程度。有时这是显而易见的：鳕鱼种群的崩溃显然是由于过度捕捞。然而，在这种直接影响之后，其他物种往往因不总是显而易见的原因而受到二次灭绝，这有可能导致进一步灭绝的级联和生态系统崩溃。预测这些级联是具有挑战性的，需要详细了解生态系统中物种之间的相互联系如何影响人类对一个物种的影响传递到与该物种没有直接联系的其他物种，这对最容易灭绝的高营养级物种（食肉动物）尤为重要。长期以来，人们一直认为，专门捕食不同猎物的食肉动物物种通过限制猎物数量，从而防止一种猎物物种竞争过另一种猎物，从而对彼此产生积极影响。这样做的后果是，如果食肉动物从群落中消失，它的猎物就失去了控制，随后可能会超过其他猎物物种，使其他食肉动物没有食物，面临灭绝。这可能是灭绝级联发生的一个重要机制，然而，很难获得这种效应的实验证据。我们已经在实验室里用简单的昆虫群落做了初步的实验，实验证明，一种食肉动物的消失确实会导致其他物种在几代内灭绝。现在的挑战是将这个模型系统扩展到更现实的规模。我们建议在野外围隔中进行实验，围隔大约为2米见方，我们可以控制生态群落的确切组成。我们将在这些昆虫群落中聚集，并对目标物种实施特定的收获制度，并跟踪这对其他物种的间接影响，特别是预测的灭绝级联是否发生。在这种情况下，我们可以操纵重要的变量，如猎物物种之间的竞争强度，并测试它们对结果的影响。我们还可以测试这样一种预测，即物种丰富和复杂的群落将更能抵抗灭绝级联，这意味着随着生物多样性的丧失，进一步丧失引发灭绝级联的可能性增加。

项目成果

Trophic assimilation efficiency markedly increases at higher trophic levels in four-level host-parasitoid food chain.

• DOI: 10.1098/rspb.2015.3043
• 发表时间: 2016-03-16
• 期刊: Proceedings. Biological sciences
• 作者: Sanders D;Moser A;Newton J;van Veen FJ
• 通讯作者: van Veen FJ

Defensive insect symbiont leads to cascading extinctions and community collapse.

• DOI: 10.1111/ele.12616
• 发表时间: 2016-07
• 期刊: Ecology letters
• 影响因子: 8.8
• 作者: Sanders D;Kehoe R;van Veen FF;McLean A;Godfray HC;Dicke M;Gols R;Frago E
• 通讯作者: Frago E

Trophic redundancy reduces vulnerability to extinction cascades.

• DOI: 10.1073/pnas.1716825115
• 发表时间: 2018-03-06
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Sanders D;Thébault E;Kehoe R;Frank van Veen FJ
• 通讯作者: Frank van Veen FJ

Plant-modified trophic interactions.

• DOI: 10.1016/j.cois.2015.02.009
• 发表时间: 2015-04
• 期刊: Current opinion in insect science
• 影响因子: 5.3
• 作者: Fj Frank van Veen

Artificial nighttime light changes aphid-parasitoid population dynamics.

• DOI: 10.1038/srep15232
• 发表时间: 2015-10-16
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Sanders D;Kehoe R;Tiley K;Bennie J;Cruse D;Davies TW;Frank van Veen FJ;Gaston KJ
• 通讯作者: Gaston KJ