Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa.

Silvia Mecenero,Jonathan F Colville,Colin M Beale,Res Altwegg,Diego Fontaneto

doi:10.1371/journal.pone.0124327

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.

Highlights

Conserving biodiversity is important for maintaining ecosystem services [1, 2] and stability [3, 4], which are essential to human welfare
We examined the relationship between butterfly species richness and human population density across South Africa to quantify the degree to which human activity overlaps with areas of high biodiversity
We tested the hypothesis that species richness and human population density are positively correlated at large spatial scales and that this correlation should be weaker at small spatial scales

Summary

Introduction

Conserving biodiversity is important for maintaining ecosystem services [1, 2] and stability [3, 4], which are essential to human welfare. The growth of the human population and activities associated with it are having increasingly negative impacts on biodiversity through habitat loss [5, 6], with a consequent increase in the rate of extinction of species [5, 7]. The extinction crisis may be exacerbated if, as suggested by some authors e.g. [8, 9], wildlife species generally share. The extinction crisis may be exacerbated if, as suggested by some authors e.g. [8, 9], wildlife species generally share

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Conclusion