# Rapid Shifts in Relative Abundance Obscure Temporal Diversity Changes in a Metacommunity

## TL;DR

The study shows how changes in insect populations can mask broader biodiversity trends, emphasizing the need to consider multiple ecological scales.

## Contribution

A novel approach to partition biodiversity changes across multiple spatial scales using an analogy to natural selection.

## Key findings

- Selection among species was more significant than selection between treatments or communities.
- Rapid shifts in aphid abundance due to immigration and selection obscured broader diversity changes.
- The approach helps disentangle mechanisms driving biodiversity changes across spatial scales.

## Abstract

Changes in biodiversity reflect processes acting at multiple spatial scales, from local to global, among habitats and within communities. This complexity makes it difficult to measure mechanisms that have traditionally interested ecologists, such as environmental filters. To resolve this, we propose an approach to partition temporal changes in biodiversity into contributions from selection at multiple scales. We applied this approach to study changes in the biodiversity of invertebrate herbivores from a large‐scale, plant community experiment. Though the experiment was designed to foster distinct insect communities due to differences in host plants, our approach showed that selection among these treatments was a negligible facet of diversity change. These effects were swamped by rapid changes in relative abundances of aphids due to both immigration and selection across the metacommunity. More broadly, our work highlights how total change in biodiversity across a biogeographic region can be partitioned into logically distinct mechanisms.

Using an analogy to natural selection, we propose a novel approach to tease apart processes shaping biodiversity at multiple spatial scales. Using data from a metacommunity study of insect herbivores, we show selection among species was more important than selection between treatments or between communities. This effect is easy to miss when studying overall changes in diversity over time.