Quantifying pairwise relationships in biodiversity through time and
space using long term data
Abstract
Understanding the strength and predictability of changes in global
biodiversity is critical for quantifying how taxa will respond to global
change. By analyzing the relationships in population trends among taxa
exposed to both biotic and abiotic pressures, we may be able to discern
these patterns, potentially facilitating the formulation of predictive
frameworks for their future shifts. However, the extent to which these
pressures can describe changes in abundances over large spatial and
temporal scales is vastly understudied. We use two global datasets
containing abundance time-series (BioTIME) and biotic interactions
(GloBI) to fit a series of hierarchical models testing whether the
yearly change in abundance of any given genus is associated with the
yearly change in abundance of another geographically proximal genus
(i.e. genus pairs) within the same study. We then use posterior
predictive modeling to assess the predictive accuracy for each genus
pair from the modeled output. Finally, we test how associations and
predictive accuracy are influenced by site latitude, GloBI interactions,
disturbance, time-series length, and taxonomic classification to assess
what ecological factors explain differences in associations and/or
predictability. Generally, we find that abundance changes between genus
pairs tend to be neutral to weakly positively associated over time and
have good predictive accuracy as long as yearly changes in abundance are
not exceedingly large (<=39%). Associations and predictive
accuracy across genus pairs vary systematically across ecological
factors and taxonomic identity, increasing with longer time-series,
towards the equator, and in disturbed habitats. Our results show that
global time-series data can illustrate meaningful, albeit variable,
relationships between genera and that these patterns are shaped by known
ecological factors. Overall, this suggests that by incorporating broad
and accessible ecological information, we can improve forecast methods
to mitigate biodiversity loss in an era of global change.