Data from: Habitat heterogeneity overrides local processes to drive the species-area relationship of benthic macroinvertebrates in shallow floodplain lakes

The species–area relationship (SAR) on islands describes how the numbers
of species increase with increasing island size (or island-like habitat,
such as lakes). Despite its conceptual importance, there is considerable
uncertainty surrounding its shape in freshwater lakes, as well as the
potential mechanisms that underlie the SAR. Here, we used
standardized sampling data of benthic macroinvertebrates
from 81 shallow lakes in the Yangtze-Huai floodplain
of China to evaluate its shape and disentangle several
mechanisms (e.g., passive sampling, colonization-extinction
dynamics and heterogeneity) underlying the SAR. At the
whole-lake level, we found an increase in the total species
richness with increasing lake area, as well as an increase in
rarefied richness controlling for sampling
effort. However, within single samples, diversity was
negatively related to lake area. This scale-dependence is because
within-lake β-diversity increased with lake area,
suggesting that heterogeneity overrides local processes to
generate the positive SAR. These patterns were only
evident for measures of diversity that equally weigh common and rare
species (i.e., species richness), and disappeared when diversity measures
that weigh common species more heavily were used. This
suggests that the influence of heterogeneity on the
SAR was largely via its influence on rarer species and
their turnover in larger lakes. Overall, our result that heterogeneity was
the primary driver of the positive SAR in this system provides an
important baseline for making predictions about biodiversity changes with
ongoing habitat loss.