Abstract:

Current unprecedented declines in biodiversity have galvanized efforts to understand how changes in biodiversity affect disease risk. Empirical evidence is mixed in understanding the relationship between loss in biodiversity and disease. While some empirical research supports a dilution effect (i.e., disease risk decreases with increasing host biodiversity), many studies support an amplification effect, and in some cases no effect. In this review, we first summarize the research progresses in this area, and introduce key research topics that include: the shape of the biodiversity-disease relationship, spatial- and context dependence of dilution effect, and the phylogenetic dilution effect. Following our summary, we discuss the disputes and criticisms in this field of research. These controversies include: whether the dilution effect is prevalent, publication bias in experimental studies, and an excessive focus by some disease ecologists on the numeric relationship between biodiversity and disease. Finally, we highlight some open questions for future research looking at dilution effect that include: the relationship between dilution effect and species coexistence, the effects of global climate change on dilution effect, the relationship between dilution effect and evolution, and the implications this research can have on policy decisions.

Key words: disease ecology, ecosystem service, amplification effect, pathogen, host, dilution effect