Eichenwald Adam J, Fefferman Nina H, Reed J Michael
Department of Biology Tufts University Medford Massachusetts USA.
Department of Ecology and Evolutionary Biology University of Tennessee Knoxville Tennessee USA.
Ecol Evol. 2024 Feb 15;14(2):e10930. doi: 10.1002/ece3.10930. eCollection 2024 Feb.
Desert communities are threatened with species loss due to climate change, and their resistance to such losses is unknown. We constructed a food web of the Mojave Desert terrestrial community (300 nodes, 4080 edges) to empirically examine the potential cascading effects of bird extinctions on this desert network, compared to losses of mammals and lizards. We focused on birds because they are already disappearing from the Mojave, and their relative thermal vulnerabilities are known. We quantified bottom-up secondary extinctions and evaluated the relative resistance of the community to losses of each vertebrate group. The impact of random bird species loss was relatively low compared to the consequences of mammal (causing the greatest number of cascading losses) or reptile loss, and birds were relatively less likely to be in trophic positions that could drive top-down effects in apparent competition and tri-tropic cascade motifs. An avian extinction cascade with year-long resident birds caused more secondary extinctions than the cascade involving all bird species for randomized ordered extinctions. Notably, we also found that relatively high interconnectivity among avian species has formed a subweb, enhancing network resistance to bird losses.
沙漠群落因气候变化面临物种丧失的威胁，但其对这种丧失的抵抗力尚不清楚。我们构建了莫哈韦沙漠陆地群落的食物网（300个节点，4080条边），以实证研究鸟类灭绝与哺乳动物和蜥蜴灭绝相比，对这个沙漠网络可能产生的级联效应。我们关注鸟类是因为它们已经从莫哈韦消失，且其相对的热脆弱性是已知的。我们量化了自下而上的次生灭绝，并评估了群落对每个脊椎动物类群丧失的相对抵抗力。与哺乳动物（造成级联损失数量最多）或爬行动物丧失的后果相比，随机鸟类物种丧失的影响相对较小，而且鸟类相对不太可能处于能在明显竞争和三营养级联模式中引发自上而下效应的营养位置。对于随机有序灭绝，常年留鸟导致的鸟类灭绝级联造成的次生灭绝比涉及所有鸟类物种的级联更多。值得注意的是，我们还发现鸟类物种之间相对较高的连通性形成了一个子网络，增强了网络对鸟类丧失的抵抗力。
