Discussion
Although patterns of relationship shared among populations of a single species should not be used to draw general biogeographic conclusions Brooks and McLennan 1991 , area relationships in A. plicata can be instructive if compared with results of other codistributed species to consider more general biogeographic patterns, patterns of phylogeographic association, and thus also patterns of ecological interaction over long periods of time. To do this, it is necessary to assume that the populations...
Dynamically Fragile versus Dynamically Robust Communities
Communities that are stable only under a limited range of environmental and ecological conditions are considered dynamically fragile, whereas communities that are stable over a wide range of conditions are dynamically robust. Figure 5.2 is a two-dimensional representation of the difference between a dynamically fragile and a dynamically robust system. Of course, a hypervolume with numerous axes would more adequately represent natural environmental conditions. A fragile community is one in which...
Conclusions 1
At this time of high disturbance and extinctions in natural systems, ecologists, paleoecologists, and conservation biologists must understand the underlying factors involved in species, community, and ecosystem stability Grimm and Wissel 1997 Palmer, Ambrose, and Poff 1997 . The examination of long-term faunal stability patterns in the fossil record can provide insights into some of the fundamental questions in ecology regarding community structure and the relationship between stability and...
The Nutrient Paradox
In ecological time, total taxonomic diversity tends to be inversely correlated with nutrient concentration, a phenomenon known as the nutrient paradox because it seems to contradict our intuition that more resources should permit greater, not less, diversity Rosenzweig and Abramsky 1993 . For example, diversity is relatively low in both eutrophic habitats, such as ponds and estuaries, and in many highly oligotrophic settings, whereas highest taxonomic diversities are observed in communities...
References Iju
Adams, C. G. 1990. Neogene larger foraminifera, evolutionary and geological events in the context of datum planes. In N. Ikebe and R. Tsuchi, eds., Pacific Neogene Datum Planes Contributions to Biostratigraphy and Chronology, pp. 47-67. Tokyo University of Tokyo Press. Allmon, W. D. 1988. Ecology of Recent turritelline gastropods Prosobranchia, Tur- ritellidae Current knowledge and paleontological implications. Palaios 3 259-284. Allmon, W. D. 1992a. A causal analysis of stages in allopatric...
Underpinnings of Mass Extinction Taxonomic and Ecological Decoupling
Perhaps one of the most interesting aspects of this analysis of mass extinctions using our approach of paleoecological levels is the phenomenon that we term taxonomic and ecological decoupling, where the relative level of ecological degradation is not as great as the degree of taxonomic degradation during a mass extinction event Droser et al. 2000 . This ecological decoupling appears to occur at the second paleoecological level. For example, as discussed, the Late Ordovician mass extinction,...
Reclining
FIGURE 4.1. General adaptive benthic strategies that are typical of A the Cambrian Evolutionary Fauna and B the Ordovician representatives of the Cambrian and Paleozoic Evolutionary Faunas after Bambach 1983 . The shaded boxes are not biologically practical strategies. Second-level changes from A to B include the addition of new Bambachian megaguilds. Third-level changes include the filling-in of Bambachian megaguilds after Droser and Sheehan 1995 . FIGURE 4.1. General adaptive benthic...
Origin of the Modern Coral Fauna of the Caribbean
The present-day coral fauna of the Caribbean is very unlike that of the Indo-Pacific, although both originated from the same Eocene-Oligocene pantropi-cal species pool. Many of these differences can be traced to two intervals of evolutionary change in the Caribbean A regional extinction in the early Miocene and a period of accelerated turnover during the Plio-Pleistocene. These two formative episodes affected both the taxonomic composition and ecological attributes of the fauna. Following an...
Evolutionary Paleoecology of Caribbean Coral Reefs
Richard B. Aronson and William F. Precht ecologists have radically altered their thinking about coral reefs, and those views continue to evolve. Coral reefs, formerly viewed as stable, equilibrial systems Newell 1971 , are now interpreted as nonequilib-rial on ecologically relevant scales of time years to decades and space landscapes to reef systems Grigg and Dollar 1990 Karlson and Hurd 1993 Edmunds and Bruno 1996 Brown 1997 . Increasing awareness of this variability is motivating a strategic...