Biotic interactions influence the projected distribution of a specialist mammal under climate change
Bateman, BL and VanDerWal, J and Williams, SE and Johnson, CN, Biotic interactions influence the projected distribution of a specialist mammal under climate change, Diversity and Distributions, 18, (9) pp. 861-872. ISSN 1366-9516 (2012) [Refereed Article]
Aim To measure the effects of including biotic interactions on climate-based
species distribution models (SDMs) used to predict distribution shifts under
climate change. We evaluated the performance of distribution models for an
endangered marsupial, the northern bettong (Bettongia tropica), comparing
models that used only climate variables with models that also took into account
Location North-east Queensland, Australia.
Methods We developed separate climate-based distribution models for the
northern bettong, its two main resources and a competitor species. We then
constructed models for the northern bettong by including climate suitability
estimates for the resources and competitor as additional predictor variables to
make climate + resource and climate + resource + competition models. We
projected these models onto seven future climate scenarios and compared predictions
of northern bettong distribution made by these differently structured
models, using a ‘global’ metric, the I similarity statistic, to measure overlap in
distribution and a ‘local’ metric to identify where predictions differed significantly.
Results Inclusion of food resource biotic interactions improved model performance.
Over moderate climate changes, up to 3.0 °C of warming, the climateonly
model for the northern bettong gave similar predictions of distribution to
the more complex models including interactions, with differences only at the
margins of predicted distributions. For climate changes beyond 3.0 °C, model
predictions diverged significantly. The interactive model predicted less contraction
of distribution than the simpler climate-only model.
Main conclusions Distribution models that account for interactions with other
species, in particular direct resources, improve model predictions in the present-
day climate. For larger climate changes, shifts in distribution of interacting
species cause predictions of interactive models to diverge from climate-only
models. Incorporating interactions with other species in SDMs may be needed
for long-term prediction of changes in distribution of species under climate
change, particularly for specialized species strongly dependent on a small number
of biotic interactions.