id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
iguana-17098	Powell, Robert	Species and Subspecies: What Do They Mean and Why Should We Care?	2004	6	.pdf	application/pdf	2080	118	53	If faced with a large number of 110 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 POWELL Cyclura stejnegeri (top), from Isla Mona (see article on p. 98), and C. onchiopsis (above left), from Navassa Island and extinct since the late 19th cen- tury, were considered subspecies of C. cornuta (above right) until the application of modern species concepts resulted in a reevaluation of distinctive characters (Powell 1999, 2000). What makes this decision even more difficult is the realization that the evolu- tion of new species usually is not a sudden occurrence, but takes time measured in many generations, sometimes extending over millennia or even periods of time best defined by geological means.	cache/iguana-17098.pdf	txt/iguana-17098.txt