Peer review is crucial to the knowledge production system and publication quality control. However, limited research has been conducted on the characteristics of anonymous reviewers and the connections between journals and reviewers. Based on the journal–reviewer coupling relationship of 477,684 reviewers and 6,058 journals from Publons, we show a highly concentrated review network with a small number of journals relying on a disproportionately high share of reviewers. The skewness in reviewer distribution is evident at various levels: journal field, country of origin, and journal impact. Moreover, we revealed significant disparities in reviewer background: Women review for fewer journals and are underrepresented among reviewers, especially in fields such as physics and mathematics and in countries such as China and Japan. Journals in fields like psychology, health, and humanities tend to rely on reviewers from a limited geographic location pool, and those based in Brazil and Japan often connect with local countries’ reviewers. We also observed homophily effects, where journals within most fields and countries, and with higher journal impact tend to share reviewers mutually. Our study provides a more comprehensive understanding of the global peer review system and highlights the need for greater diversity and inclusion in the peer review process.

Historically Black Colleges and Universities (HBCUs) play a foundational role in promoting equality in U.S. higher education and society. Studying faculty transitions and research dynamics at HBCUs is crucial to understanding and addressing these institutions’ challenges, such as the brain drain and its relationships with faculty research practices. By tracking the affiliation changes of 139 professors and their research outcomes (consisting of 4,269 publications) and comparing them with a matched control group with similar backgrounds, we revealed a moving penalty for professors moving from Predominantly White Institutions (PWIs) to HBCUs, who experienced declines in research productivity and citation impact. In contrast, professors transitioning from HBCUs to PWIs benefited from the moving premium of increasing high-impact publications. Professors at HBCUs tend to increase their collaborations with PWIs before transitioning, while those moving to PWIs reduce their collaborations with HBCUs. Our findings highlight the ongoing challenges HBCUs face and underscore the need for comprehensive strategies to strengthen these institutions’ research functionality and ultimately their overall academic standing.