The observed architecture of ecological and socio-economic networks differs significantly from that of random networks. From a network science standpoint, non-random structural patterns observed in real networks call for an explanation of their emergence and an understanding of their potential systemic consequences. This article focuses on one of these patterns: nestedness. Given a network of interacting nodes, nestedness can be described as the tendency for nodes to interact with subsets of the interaction partners of better-connected nodes. Known since more than $80$ years in biogeography, nestedness has been found in systems as diverse as ecological mutualistic organizations, world trade, inter-organizational relations, among many others. This review article focuses on three main pillars: the existing methodologies to observe nestedness in networks; the main theoretical mechanisms conceived to explain the emergence of nestedness in ecological and socio-economic networks; the implications of a nested topology of interactions for the stability and feasibility of a given interacting system. We survey results from variegated disciplines, including statistical physics, graph theory, ecology, and theoretical economics. Nestedness was found to emerge both in bipartite networks and, more recently, in unipartite ones; this review is the first comprehensive attempt to unify both streams of studies, usually disconnected from each other. We believe that the truly interdisciplinary endeavour -- while rooted in a complex systems perspective -- may inspire new models and algorithms whose realm of application will undoubtedly transcend disciplinary boundaries.

中文翻译：

---

复杂网络中的嵌套：观察、出现和影响

观察到的生态和社会经济网络的架构与随机网络的架构显着不同。从网络科学的角度来看，在真实网络中观察到的非随机结构模式需要对其出现的解释和对其潜在系统后果的理解。本文重点介绍其中一种模式：嵌套。给定一个交互节点网络，嵌套性可以描述为节点与连接更好的节点的交互伙伴的子集交互的趋势。早在 80 多美元的生物地理学中就已为人所知，在生态共生组织、世界贸易、组织间关系等多种系统中发现了嵌套性。这篇评论文章侧重于三个主要支柱：观察网络嵌套的现有方法；旨在解释生态和社会经济网络中嵌套性出现的主要理论机制；交互的嵌套拓扑对给定交互系统的稳定性和可行性的影响。我们调查各种学科的结果，包括统计物理学、图论、生态学和理论经济学。发现嵌套性出现在双向网络中，最近也出现在单方网络中。这篇综述是第一次综合尝试统一这两种研究流，通常是相互脱节的。