Schupp (1995) discusses the quantity, quality, and effectiveness of animal-mediated seed dispersal. He emphasizes that disperser effectiveness is the contribution a disperser makes to plant reproduction. Effectiveness has both quantitative and qualitative components. Quantity depends on the number of visits to a plant and the number of seeds dispersed per visit. Quality depends on the treatment of seeds in the disperser's mouth and gut, and the probability that a dispersed seed will survive and become an adult. The paper reviews how disperser behavior, morphology, and physiology influence these components. It also addresses the importance of quantity versus quality in determining disperser effectiveness and whether dispersers are inherently high or low quality. The paper highlights the need for a consistent terminology to study disperser effectiveness. It proposes a hierarchical framework for understanding the factors influencing effectiveness. Disperser effectiveness is ideally defined by the contribution to future plant reproduction. However, reliable estimates of this are difficult, so empirical measures based on seedlings are often used. These may be misleading in some cases, as the consequences of seed dispersal can last beyond the seedling stage. The paper also discusses the importance of incorporating plant demography into seed dispersal studies. Empirically, effectiveness is calculated as the product of quantity and quality. Quantity is influenced by the number of visits and seeds per visit. Quality is influenced by seed treatment and deposition. Both components are affected by the biology of the disperser and the plant. The paper concludes that studies of disperser effectiveness should consider individual, population, and species levels. It emphasizes the importance of understanding the factors that influence seed dispersal effectiveness for ecological and evolutionary studies.Schupp (1995) discusses the quantity, quality, and effectiveness of animal-mediated seed dispersal. He emphasizes that disperser effectiveness is the contribution a disperser makes to plant reproduction. Effectiveness has both quantitative and qualitative components. Quantity depends on the number of visits to a plant and the number of seeds dispersed per visit. Quality depends on the treatment of seeds in the disperser's mouth and gut, and the probability that a dispersed seed will survive and become an adult. The paper reviews how disperser behavior, morphology, and physiology influence these components. It also addresses the importance of quantity versus quality in determining disperser effectiveness and whether dispersers are inherently high or low quality. The paper highlights the need for a consistent terminology to study disperser effectiveness. It proposes a hierarchical framework for understanding the factors influencing effectiveness. Disperser effectiveness is ideally defined by the contribution to future plant reproduction. However, reliable estimates of this are difficult, so empirical measures based on seedlings are often used. These may be misleading in some cases, as the consequences of seed dispersal can last beyond the seedling stage. The paper also discusses the importance of incorporating plant demography into seed dispersal studies. Empirically, effectiveness is calculated as the product of quantity and quality. Quantity is influenced by the number of visits and seeds per visit. Quality is influenced by seed treatment and deposition. Both components are affected by the biology of the disperser and the plant. The paper concludes that studies of disperser effectiveness should consider individual, population, and species levels. It emphasizes the importance of understanding the factors that influence seed dispersal effectiveness for ecological and evolutionary studies.