THE OFFICIAL GUIDE TO 



TREK NEW ZEALAND 



Fly the award winning service of 

 Air New Zealand and experience 

 the environmental destination of 

 the 1990's. 



New Zealand is an 

 outdoor enthusiasts mecca, 

 criss-crossed with a network of 

 walking trails and readily avail- 

 able guided treks that meander 

 through pristine valleys, bush 

 clad hillsides and above treelined 

 tundra. The Routeburn; The 

 Greenstone; The Hollyford; The 

 Abel Tasman and the world 

 famous Milford Track. 



Free of poisonous reptiles or any 

 carnivorous animals New Zealand 

 is the ideal setting for those who 

 love to touch nature. 



Whether it's the Coastal Abel 

 Tasman Walk, the mellow river 

 banks of the Greenstone, or the 

 deep lush native forest of the 

 World Famous Milford Track, 

 you'll find a walk to satisfy your 

 heart's desire. 



For your free official color guide 

 to "Trek New Zealand" please 

 contact... 



1 (800) 468 2665 or write to: 

 10UNT COOK LINE 



^ air new ZEaiana 



the pride of the pacific 



I960 East Grand Avenue, Suite 910, 

 El Segundo, CA 90245 



Homo sapiens is one species, mammals a 

 few thousand. By contrast, nearly a mil- 

 lion species of insects have been described 

 (and several millions more remain undis- 

 covered and uncataloged). Insects repre- 

 sent more than 70 percent of all named an- 

 imal species. 



So why are insects so diverse? Many 

 answers have been offered, and the solu- 

 tion will be some complex combination of 

 the good arguments. Small size, great eco- 

 logical diversity, rapid geographic disper- 

 sal, have all been mentioned and are prob- 

 ably valid as partial explanations, but one 

 other factor always stands out in the con- 

 ventional list of reasons: coevolution with 

 flowering plants. The angiosperms, or 

 flowering plants, are by far the most di- 

 verse group in their kingdom. Many spe- 

 cies are fertilized by insects in a mutually 

 beneficial arrangement that supplies food 

 to the insects while transporting pollen 

 from flower to flower. 



So intricate, and so mutually adapted, 

 are the features of both flower and insect in 

 many cases — special colors and odors to 

 attract the insects, exquisitely fashioned 



mouthparts to extract flie nectar, for ex- 

 ample — that this pairing has become our 

 classic example of coevolution, or promo- 

 tion of adaptation and diversity by interac- 

 tion among organisms during their evolu- 

 tion. (Darwin wrote an entire book on the 

 subject, using the classic case of intri- 

 cately coadapted orchids and their insect 

 pollinators.) Thus, a received truth of evo- 

 lutionary biology has proclaimed that in- 

 sects are so diverse, in no small part, be- 

 cause flowering plants are so varied — and 

 each plant evolves its pollinator (and vice 

 versa). 



Sounds good, but is it true? The fossil 

 record suggests an obvious test, but curi- 

 ously, no one had ever carried out the pro- 

 tocol until my colleagues Conrad Laban- 

 deira and Jack Sepkoski published a paper 

 last July ("Insect Diversity in the Fossil 

 Record," Science, July 16, 1993, pp. 310- 

 15). Insects arose in the Devonian period, 

 but began a major radiation in diversity 

 during subsequent Carboniferous times, 

 some 325 million years ago. An- 

 giosperms, by contrast, arose much later. 

 Their first fossils are found in early Creta- 



1 8 Natural History 2/94 



