Developing Pressure Indicators for Europe
Edited by Anil Markandya and Nick Dale
Chapter 10: Biodiversity
P. Devillers 1. THE BIODIVERSITY CRISIS The expression ‘biological diversity’ or ‘biodiversity’ refers to ‘the variability of living organisms of all origins, including the diversity of species as well as between species and that of ecosystems’ (Glowka et al., 1994). Three fundamental components can be recognized. First, the diversity of species, and therefore of all independent manifestations of the evolutionary process. Second, the diversity of populations, and therefore of the capabilities of species to adapt to a changing environment and to colonize new niches. Third, the diversity of communities, and therefore of the network of interactions between species that is the basis of small- and large-scale landscape mosaics. The ﬁrst two components decrease with global extinctions of species or populations and with loss of intrapopulational genetic diversity, and increase as a result of speciation or incipient speciation phenomena and with gain of genetic diversity. The third component decreases with local extinctions which impoverish, simplify and uniformize communities, and increases with local colonization or recolonization successes. The global evolutionary phenomenon resulting from the interaction of these events is a historical process, unique and non-predictable. In the course of this process, the evolution of biodiversity is characterized by alternation between periods of relatively stable growth and short periods of massive extinction (Gould, 1989, 1993). The growth periods are governed by the stochastic frequency of speciation and extinction events, largely controlled by local abiotic factors (Cracraft, 1982; Eldredge, 1989), and by the Darwinian determinism which underpins the evolution of populations. The periods of...
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