Abstract:
Wildlife and humans tend to prefer the same productive environments, yet high human densities
often lead to reduced biodiversity. Species richness is often positively correlated with
human population density at broad scales, but this correlation could also be caused by unequal
sampling effort leading to higher species tallies in areas of dense human activity. We
examined the relationships between butterfly species richness and human population density
at five spatial resolutions ranging from 2' to 60' across South Africa. We used atlas-type
data and spatial interpolation techniques aimed at reducing the effect of unequal spatial
sampling. Our results confirm the general positive correlation between total species richness
and human population density. Contrary to our expectations, the strength of this positive
correlation did not weaken at finer spatial resolutions. The patterns observed using total
species richness were driven mostly by common species. The richness of threatened and
restricted range species was not correlated to human population density. None of the correlations
we examined were particularly strong, with much unexplained variance remaining,
suggesting that the overlap between butterflies and humans is not strong compared to other
factors not accounted for in our analyses. Special consideration needs to be made regarding
conservation goals and variables used when investigating the overlap between species
and humans for biodiversity conservation.
