Changing juvenile growth patterns in tropical trees: selective effects, history, or both?

In this article, the author discusses the result of a study which examines the changing juvenile growth patterns in tropical trees. He highlights that the study found that the juvenile selection effect was not ubiquitous. He assesse that the study raised questions, such why did an extremely shade-intolerant tree species not show a juvenile selection effect and would older trees of relatively shade-tolerant species show faster growth.