title: Macroevolutionary trends: new perspectives on the roles of adaptation and incidental effect.
abstract: Trends, long-term directional tendencies in evolution, are traditionally interpreted as selected for and adaptive. Alternatively, trends may be unselected effects of characters and processes within species: the effect hypothesis. Thus adaptations of organisms, varying among species, were selected for immediate fitness, but they may also incidentally determine different speciation and extinction rates and trends.
authors.forename: E S
authors.initials: ES
authors.lastname: Vrba