Relative genome size variation in the African agroforestry tree Parkia biglobosa (Fabaceae: Caesalpinioideae) and its relation to geography, population genetics and morphology

Variation in genome size and in chromosome number can be linked to genetic, morphological and ecological characteristics, and thus be taxonomically significant. We screened the relative genome size (RGS) and counted the number of mitotic chromosomes in the African agroforestry tree Parkia biglobosa, a widely distributed savannah species that shows conspicuous morphological clinal variation and strong genetic structure, and tested for linkage of RGS variation to geography, leaf morphology, and population genetic variation. An improved protocol for the preparation of chromosomes was developed. The study is based on 58 individuals from 15 populations covering most of the distribution range of the species. We observed differences in RGS among individuals of up to 10.2 %, with some of the individuals differing statistically in RGS from the bulk of screened individuals. Most of the RGS variation was within populations whereas variation was unrelated to any of the tested features of the species. Those chromosome numbers which could be exactly established were invariable 2n = 2x = 26. In conclusion, there was no evidence from the karyological data for structured intra-specific taxonomic heterogeneity.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author