In species-rich rainforests of the New World tropics most trees have broad geographic distributions–from Mexico to Bolivia and sometimes to the West Indies. Either they have excellent dispersal abilities, or they established broad ranges prior to the formation of present geographic barriers. In a study featured in American Naturalist, Christopher Dick, Kobinah Abdul-Salim and Eldredge Bermingham address these questions in the first phylogeographic study of a rainforest tree.

Everyone has mitochondria--the famous "powerhouse" of eukaryotic cells can hardly be considered a disease. But mitochondria may be relicts of an ancient invasion, an epidemic that took place 500 million years ago. Wolbachia, a bacterial group related to the ancestor of mitochondria, infects a wide range of insects and manipulates host reproduction to promote its own survival. A posse, with $5 million from the US National Science Foundation, is on its trail.

Of the 10 million plus species thought to exist on this planet, a mere 2 million are known to science. Others dwell in inaccessible locations--deep sea vents or hard-to-reach tropical treetops. To collect the best information available to date on tropical forest insects and their habitats, thirty researchers will use state-of-the-art canopy access techniques to sample nine 400m2 patches of Panamanian rainforest from September 22-October 31, 2003.

No coral reef system in the world can be considered pristine, concludes an exhaustive historical analysis of human exploitation of reef ecosystems in the August 15 issue of the journal Science. The hunting of big turtles, fish, manatees and crocodiles began a process of reef decline exacerbated in the modern era by continued overfishing and global warming.

During animal courtship males use strikingly beautiful signals as they compete for the amorous attention of females. Examples include bright feathers of male birds and evening songs of male frogs or crickets. Why are some signals more attractive than others? Females should be attracted to signals that indicate the quality of a suitor as mate and father. But scientist John Christy from the Smithsonian and colleagues discovered a signal that is attractive for another reason.

Up to 20 layers of transparent scales on butterfly wings scatter white light to produce brilliant blue structural color. Alison Sweeney, Duke University, and collaborators at the Smithsonian Tropical Research Institute report in Nature that polarized light from iridescent female Heliconius butterflies functions as a mating signal. This may be the first example of mate recognition based on polarized light. Physical properties of wing scales may play an important role in speciation of Heliconius butterflies.