Data from: Temperature accounts for the biodiversity of a hyperdiverse group of insects in urban Los Angeles

The urban heat island effect is a worldwide phenomenon that has been
linked to species’ distributions and abundances in cities. However,
effects of urban heat on biotic communities are nearly impossible to
disentangle from effects of land cover in most cases because hotter urban
sites also have less vegetation and more impervious surfaces than cooler
sites within cities. We sampled phorid flies, one of the largest, most
biologically diverse families of true flies (Insecta: Diptera: Phoridae),
at 30 sites distributed within the central Los Angeles Basin, where we
found that temperature and the density of urban land cover are decoupled.
Abundance, richness, and community composition of phorids inside urban Los
Angeles were most parsimoniously accounted for by mean air temperature in
the week preceding sampling. Sites with intermediate mean temperatures had
more phorid fly individuals and higher richness. Communities were more
even at urban sites with lower minimum temperatures and sites located
further away from natural areas, suggesting that communities separated
from natural source populations may be more homogenized. Species
composition was best explained by minimum temperature. Inasmuch as warmer
areas within cities can predict future effects of climate change, phorid
fly communities are likely to shift non-linearly under future climates in
more natural areas. Exhaustive surveys of biotic communities within
cities, such as the one we describe here, can provide baselines for
determining the effects of urban and global climate warming as they
intensify.