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The high alpha-diversity of tropical forests has been amply documented, but beta-diversity-how species composition changes with distance-has seldom been studied. We present quantitative estimates of beta-diversity for tropical trees by comparing species composition of plots in lowland terra firme forest in Panama, Ecuador, and Peru. We compare observations(More)
About 3 million years ago (Ma), the Isthmus of Panama joined the Americas, forming a land bridge over which inhabitants of each America invaded the other-the Great American Biotic Interchange. These invasions transformed land ecosystems in South and Middle America. Humans invading from Asia over 12000 years ago killed most mammals over 44 kg, again(More)
  • E G Leigh
  • 1983
In a system of N populations of n reproductive individuals apiece, in which each population has constant variance v(2) and lasts L generations, group selection on a quantitative character has a reasonable chance of overriding selection within populations if (and only if) the populations never exchange migrants, each population is founded by colonists from a(More)
We describe the analogy between the theory of natural selection on sex ratio in newborn gonochores (which will not change sex), and on the age of sex change in sequential hermaphrodites (which are all born into one sex and change to the other later on). We also discuss the conditions under which natural selection favors sequential hermaphrodites over(More)
MacArthur and Levins suggested that species persist by specializing as much as variation in their environments allows, thus avoiding competitive displacement. Accordingly, more species should coexist in stabler environments. Empirical analyses of trade-offs suggest that, indeed, 'the jack of all trades is master of none'. Diversity represents a balance(More)
We use Hubbell's neutral theory to predict the impact of habitat fragmentation on Amazonian tree communities. For forest fragments isolated for about two decades, we generate neutral predictions for local species extinction, changes in species composition within fragments, and increases in the probability that any two trees within a fragment are(More)
The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would(More)
In this book, Robert Asher reviews some of the overwhelming evidence for evolution, explains why evolutionary biology should pose no threat to Christian faith, and refutes oft-repeated criticisms of evolution by natural selection that many non-biologists find convincing. Asher does a wonderful job with the evidence for evolution , although non-biologists(More)