Complexity breeds stability?   2 comments

Complexity breeds stability?.


Posted November 29, 2012 by felipedelbosque in Shared Blogs

2 responses to “Complexity breeds stability?

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  1. The patterns are not as simple as you suggest. I am a biological oceanographer working on zooplankton. It is quite clear in the oceans that plankton assembages at high latitudes are less diverse (species rich) than at low latitudes. This pattern extends to all depths at least down to 2000m. At high latitudes the water column is more variable seasonally, and the inferrence is that stability (and predictability) of the physical envoronment allows more species to co-exist. However, when one looks at the palaeo record in littoral environments it is apparent that species that are themselves high variable and hence are able to adapt to change persist longer in the geological record than specialist species. This is well documented in the cowries, in which high diversity assemblages are composed of a greater proportion of specialist species and therefore far more vulnerable to enivironmental fluctuations whether natural or anthropogenic. So speciation rates (leading to increased diversity) and extinction rates (leading to decreases in diversity) are higher in specialist species with a low tolerance to environmental fluctuations. Another factor is seen in the South African grasslands where the seasonal grazing by migrating antelope creates much more diverse plant assemblages. When the grazing is either removed OR becomes year-round (because of farming), the species richness rapidly declines. In rain forests it is the structural diversity of the ecosystem that provides a more varied assortment of habitats so mopre species can be packed in. It is much the same in the tropical ocean where the physical environment (the water column) is bathymetrically more structured.


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