IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Willis, K.J.; Whittaker, R.J. | |
| Species Diversity - Scale Matters | |
| 2002 Science (295): 1245-1248 | |
As predictions of the loss of global biodiversity grow increasingly pessimistic, identifying the factors that determine species richness has become a hot topic. The best-known pattern in species diversity is the gradient ranging from low at the poles to high at the equator. This pattern is so general across so many taxa that it suggests the existence of an equally general explanation. Much attention, therefore, has been given to finding the mechanism that explains patterns of species richness, with the underlying assumption that whatever scale the relationship is measured at can be scaled up or down in simple fashion. If this were so, a model that successfully accounts for local patterns in richness could be scaled up to account for variations seen at a coarser regional or even global scale. This reasoning resembles that used to explain evolutionary change, where variations manifest over decades or centuries can be scaled up to describe the more dramatic patterns of macroevolutionary change over geological time. But, as some evolutionists have argued (1), biological and environmental systems are more complex than this. It is becoming increasingly apparent that the factors best accounting for patterns of biodiversity seem to be delimited by scale. This finding needs to be taken into account when assessing present or predicting future worldwide patterns of species richness. |
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(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union) |