Complementariedad temática estructurada y pluralismo en ecosistemas digitales

The predominant assumption in media studies holds that media concentration leads to content homogenization and, consequently, a decline in pluralism. However, the dynamics of digital ecosystems have raised questions regarding the validity of this relationship in contemporary contexts. This study analyzes the configuration of the news agenda on X/Twitter within a highly concentrated Chilean regional market, proposing the concept of structured thematic complementarity as a form of systemic articulation among differentiated editorial profiles. The analysis is based on 8509 tweets and utilizes a design that integrates contingency tests, diversity indices, cluster analysis, and logistic regression models. The results show that concentration does not lead to agenda homogenization but rather to patterns of thematic specialization and differentiation that operate complementarily at the ecosystem level (χ² = 1589.16, p < .001; Cramer's V = .250). This organization is reflected in two predominant clusters (institutional-balanced and specialized-differentiated), with distinctive content markers identified via logistic regression (OR = 1.86-7.78). Diversity indices confirm this configuration, from more heterogeneous topics (H”² = 2.189) to more specialized ones (H”² = 1.993). The findings suggest that diversity can be understood as a relational property of the regional news ecosystem rather than a simple aggregation of individual agendas, providing situated empirical evidence to the debate on information pluralism in environments of high media conglomeration.