Temporal variability of carabid beetles as a function of geography, environment, and species

Populations of species fluctuate through time and across geographic space. Identifying the potential drivers of temporal variability in population dynamics is a fundamental aim of population ecology, with clear implications to understanding population extinction risk, the influence of diversity on composite community scale variability, and the extent to which temporal variability is driven by exogenous (e.g., climate) or endogenous (e.g., life history) factors. We used data from the National Ecological Observatory Network (NEON) consisting of over 750 carabid beetle species systematically sampled between 2013 and 2021 across 47 terrestrial sites in the USA to examine the relative roles of geographic location, environmental gradients, and species identity on temporal variability. We find an effect of species taxonomic identity on resulting temporal variability in abundance both at site-level and taxonomy-level scales. Environmental variables (mean annual temperature and precipitation and seasonality in temperature and precipitation) and geographic position (latitude and longitude) were not strongly related to temporal variability, and there was no spatial signal in site-level mean temporal variability. The importance of species to temporal variability highlights the role of life history differences across species, resulting in a mean shift in population growth rate, as a potentially more important driver than aspects of site and environment that may relate more to temporal changes in population growth rates.