标题： 从边缘到主流：社交媒体对话中的社群规模与参与度 显示英文标题

标题： From Niche to Mainstream: Community Size and Engagement in Social Media Conversations

摘要： 公共话语的架构已被社交媒体平台深刻重塑，这些平台以前所未有的规模和复杂性中介互动。 本研究分析了在六个平台上33年间的用户行为，探讨对话和社区的规模如何影响对话动态。 我们的研究结果表明，较小的平台促进了更丰富、更持久的互动，而较大的平台则推动了更广泛但短暂的参与。 此外，我们观察到，随着社区规模的增长，用户重新参与对话的倾向会下降，但在利基环境中是一个明显的例外，其中参与度依然强劲。 这些发现表明平台架构、用户参与和社区动态之间存在相互依赖关系，揭示了数字生态系统如何塑造公共话语的结构和质量。 显示英文摘要

摘要： The architecture of public discourse has been profoundly reshaped by social media platforms, which mediate interactions at an unprecedented scale and complexity. This study analyzes user behavior across six platforms over 33 years, exploring how the size of conversations and communities influences dialogue dynamics. Our findings reveal that smaller platforms foster richer, more sustained interactions, while larger platforms drive broader but shorter participation. Moreover, we observe that the propensity for users to re-engage in a conversation decreases as community size grows, with niche environments as a notable exception, where participation remains robust. These findings show an interdependence between platform architecture, user engagement, and community dynamics, shedding light on how digital ecosystems shape the structure and quality of public discourse.