DNA content for Asian pines parallels New World relatives
Additional Document Info
Nuclear DNA content values for 13 Asian or Eurasian pine species and 5 additional New World species were used to test the latitudinal or thermal regime hypothesis. This hypothesis is based on an observed correlation between DNA content and thermal regime for fish, zooplankton, salamanders, and some flowering plants. The Asian pine results provided no support for the latitudinal hypothesis; Asian tropical pine species did not have smaller genomes than their temperate or boreal relatives. DNA content of haploid megagametophyte tissue varied from 21.85 pg/C for hard pine Pinus densiflora Sieb. & Zucc. to 29.59 pg/C for soft pine Pinus bungeana Zucc. Pinus merkusii Jung. & De Vriese (29.63 pg/C) was the exceptional hard pine, with a genome size larger than many soft pines. The mean DNA content of Asian soft pines exceeded Asian hard pines ( 3.22 pg/C), a parallel to the previously reported trends for New World pines. No continental effect was detected. Based on 46 pines species sampled in centers of species diversity in Asian and the New World, soft pines had mean DNA content which exceeded hard pines by 4.97 pg/C.