Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa.
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.
Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa; South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, South Africa; Department of Biodiversity and Conservation Biology, University of the Western Cape, Belville, South Africa.
Silvia
S
Mecenero
South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, South Africa; Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch, South Africa.
Res
R
Altwegg
South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, South Africa; Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch, South Africa.
Jonathan F
JF
Colville
Department of Biology, University of York, Heslington, York, United Kingdom.
Colin M
CM
Beale
D000818:Animals; D044822:Biodiversity; D002080:Butterflies / Q000145:classification* / Q000502:physiology; D003247:Conservation of Natural Resources; D006801:Humans; D008954:Models, Biological; D011156:Population Density; D011157:Population Dynamics; D013019:South Africa