Divergent Perspectives on Landscape Connectivity Reveal Consistent Effects from Genes to Communities

Landscape connectivity is increasingly emphasized due to its relevance for interpreting effects of environmental change. Yet substantial uncertainty remains regarding the quantification of connectivity and the extent to which connectivity influences biodiversity. We review and synthesize 370 articles published since 2005 on the quantification and effects of landscape connectivity on biodiversity. We find a notable change in the quantification of connectivity from structural to functional approaches, a rise in network approaches, and a decline in approaches based on metapopulation theory. Most studies (54 %) did not test for the effects of connectivity, but of those that did, 91 % found effects on biodiversity, with over five times as many positive as negative effects reported. These effects were largely consistent across levels of biological organization, despite diverse perspectives on movement and connectivity across these domains. Nevertheless, we argue that several outstanding issues need to be addressed to advance our understanding of the effects of connectivity and its importance for conservation. These issues include the need for greater emphasis on estimating connectivity effects, explicitly incorporating the problem of scale, capturing impacts of movement processes relevant to different levels of organization, proper accounting of uncertainty, and isolating connectivity effects relative to other issues influencing biodiversity.