Integration of dispersal data into distribution modeling: what have we done and what have we learned?

Abstract

Inclusion of dispersal data in models of species’ distributions in response to environmental change has been advocated for more than 15 years. We investigated whether there has been a shift in recent publications to include dispersal processes and how dispersal estimates explicitly change the conclusions of analyses. To address this question, we conducted a systemic review of the literature to assess what kinds of dispersal data and methods are being included in species distribution models across taxa. We collected metadata on 6,406 publications, 907 of which included dispersal data. The proportion of papers that included dispersal data in estimates of the species’ range increased from 8% to 20% from 1991 to 2017. Evaluation of a subsample of 200 papers showed no evidence for differences in taxa studied between dispersal and non-dispersal publications, with most studies focused on North America or Europe. Dispersal was incorporated at a higher frequency in studies from South America, Africa, and island systems. We found that forecasting models predicting range shifts with climate change rarely used dispersal data, but when they did, range shift projections were greatly affected. Our simulation models, in which a range of dispersal estimates were included, showed that projections were greatly influenced by dispersal distance assumptions. We summarize best practices for future research on distributions, including potential methodologies for dispersal integration and highlight the problems if dispersal is ignored.