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Biologists have long been fascinated by the exceptionally high diversity displayed by some evolutionary groups. Adaptive radiation in such clades is not only spectacular, but is also an extremely complex process influenced by a variety of ecological, genetic, and developmental factors and strongly dependent on historical contingencies. Using modeling approaches, we identify 10 general patterns concerning the temporal, spatial, and genetic/morphological properties of adaptive radiation. Some of these are strongly supported by empirical work, whereas for others, empirical support is more tentative. In almost all cases, more data are needed. Future progress in our understanding of adaptive radiation will be most successful if theoretical and empirical approaches are integrated, as has happened in other areas of evolutionary biology.

Identification of general properties of evolutionary radiations has been hindered by the lack of a general statistical and phylogenetic approach applicable across diverse taxa. We present a comparative analytical framework for examining phylogenetic patterns of diversification and morphological disparity with data from four iguanian-lizard taxa that exhibit substantially different patterns of evolution. Taxa whose diversification occurred disproportionately early in their evolutionary history partition more of their morphological disparity among, rather than within, subclades. This inverse relationship between timing of diversification and morphological disparity within subclades may be a general feature that transcends the historically contingent properties of different evolutionary radiations., Evolutionary radiation--cladogenesis accompanied by ecological and morphological disparity among lineages--has been studied for more than a century (1-3). Recent debate has centered on whether general rules characterize patterns of radiation [...]

We document the decimation and recovery of the commonest lizard species, Anolis sagrei, on 66 islands in the Bahamas that were directly hit by Hurricane Floyd in September 1999. Before the hurricane, an island's area was a better predictor of the occurrence of A. sagrei than was its altitude. Immediately after, altitude was a better predictor: Apparently all lizards on islands lower than about 3 meters maximum elevation perished in the storm surge. After about 1 year, area again became the better predictor. By 19 months after the hurricane, A. sagrei populations occurred on 88% of the islands they formerly occupied. Recovery occurred via overwater colonization and propagation from eggs that survived inundation, mechanisms that were enhanced by larger island area. Thus, natural processes first destroyed and then quickly restored a highly regular species-area distribution., The community species-area relation, describing the increase of species number with increasing area, is one of ecology's most pervasive regularities--even, perhaps, one of its few 'laws' (1-6). This curve is [...]

Population phenomena, which provide much of the underlying basis for the theoretical structure of island biogeography, have received little direct study. We determined a key population trait--survival--in the Bahamian lizard Anolis sagrei on islands with an experimentally introduced predatory lizard and on neighboring unmanipulated islands. On unmanipulated islands, survival declined with several variables, most notably vegetation height: The island with the shortest vegetation had nearly the highest survival recorded for any lizard. On islands with the introduced predator, which forages mostly on the ground, A. sagrei shifted to taller vegetation; unlike on unmanipulated islands, its survival was very low on islands with the shortest vegetation but was higher on the others. Thus, species introduction radically changed a resident species' relation of survival to a key island-biogeographical variable., When MacArthur and Wilson first proposed their highly influential equilibrium theory of island biogeography (1), a main objective was to predict patterns of species richness as a function of island [...]

Lizard and spider populations were censused immediately before and after Hurricane Lili on islands differentially affected by the storm surge. The results support three general propositions. First, the larger organisms, lizards, are more resistant to the immediate impact of moderate disturbance, whereas the more prolific spiders recover faster. Second, extinction risk is related to population size when disturbance is moderate but not when it is catastrophic. Third, after catastrophic disturbance, the recovery rate among different types of organisms is related to dispersal ability. The absence of the poorer dispersers, lizards, from many suitable islands is probably the result of long-lasting effects of catastrophes., Major natural disturbances such as hurricanes and volcanic eruptions may be so catastrophic that biotas in exposed areas are scarred and even reshaped for years to come. Although major disturbances [...]

The theory of historical contingency proposes that unique past events have a large influence on subsequent evolution (1-3). A corollary is that repeated occurrences of an evolutionary event would result […]

Phylogeny, Ecology, and Behavior. A Research Program in Comparative Biology. Daniel R. Brooks and Deborah A. McLennan. University of Chicago Press, Chicago, IL, 1991. xii, 434 pp., illus. $45; paper, [...]

Reports on the impact of catastrophic hurricane on island populations. Lizard and spider populations being censused immediately before and after Hurricane Lili on islands differentially affected by the storm surge; Three general propositions that the research results support; Suggestion that the absence of the poorer dispersers, lizards, from many suitable islands is probably the result of long-lasting effects of catastrophes.

The article discusses molecular and morphological phylogenies, with a focus on lizard phylogenetics and unresolved discrepancies between data collected through DNA analysis and x-ray computed tomography. Topics include anatomical synapomorphy of the suborder Iguania, the apparent pervasiveness of convergent evolution, and evolutionary systematics. Additional information is presented on molecular phylogenetic analysis of iguanians, morphological homoplasy, and ancestral lizard tongue morphologies.

The article offers perspective on research reported by Sinervo et al. elsewhere in the issue on lizards and population extinctions deemed attributable to the effects of global warming. The authors use a biological model to forecast lizard population extinctions. The greatest impact on lizard populations studied in Mexico was shown to occur during reproduction in spring when lizards demand the most energy. Studies that Sinervo et al. conducted on 4 S. serrifer populations are illustrated and discussed.

A letter to the editor is presented in response to the article "Budget Crunch to Shrink Science Programs at Chicago's Field Museum," by V. Morell in the January 4, 2013 issue.

G. G . Simpson, one of the chief architects of evolutionary biology's modern synthesis, proposed that diversification occurs on a macroevolutionary adaptive landscape, but landscape models are seldom used to study adaptive divergence in large radiations. We show that for Caribbean Anolis lizards, diversification on similar Simpsonian landscapes leads to striking convergence of entire faunas on four islands. Parallel radiations unfolding at large temporal scales shed light on the process of adaptive diversification, indicating that the adaptive landscape may give rise to predictable evolutionary patterns in nature, that adaptive peaks may be stable over macroevolutionary time, and that available geographic area influences the ability of lineages to discover new adaptive peaks. [ABSTRACT FROM AUTHOR]

The article discusses a study of the presence of founder effects and natural selection in differentiating populations of brown anoles (Anolis sagrei) introduced on several islands of the Bahamas from randomly-selected pairs of lizards. The researchers found variations between the island populations in their genetic and morphological traits such as hindlimb length, despite the fact that the lizards were adapting to similar habitats with narrow vegetation. These results indicate that founder effects are a significant influence on the evolutionary divergence of populations, even in the face of pressures from natural selection.