DO SURFACE PLANT AND SOIL SEED BANK POPULATIONS DIFFER GENETICALLY - A MULTIPOPULATION STUDY OF THE DESERT MUSTARD LESQUERELLA-FENDLERI (BRASSICACEAE)

Citation
Rj. Cabin et al., DO SURFACE PLANT AND SOIL SEED BANK POPULATIONS DIFFER GENETICALLY - A MULTIPOPULATION STUDY OF THE DESERT MUSTARD LESQUERELLA-FENDLERI (BRASSICACEAE), American journal of botany, 85(8), 1998, pp. 1098-1109
Citations number
62
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
0002-9122
Volume
85
Issue
8
Year of publication
1998
Pages
1098 - 1109
Database
ISI
SICI code
0002-9122(1998)85:8<1098:DSPASS>2.0.ZU;2-F
Abstract
Seed banks are an important component of many plant populations, but f ew empirical studies have investigated the genetic relationship betwee n soil seeds and surface plants. We compared the genetic structure of soil seeds and surface plants of the desert mustard Lesquerella fendle ri within and among five ecologically diverse populations at the Sevil leta National Wildlife Refuge in Central New Mexico. At each site, 40 Lesquerella surface plants and 40 samples of soil seeds were mapped an d genetically analyzed using starch gel electrophoresis. Overall allel e frequencies of soil seeds and surface plants showed significant diff erences across the five populations and within three of the five indiv idual populations. Surface plants had significantly greater amounts of single and multilocus heterozygosity, and mean surface plant heterozy gosity was also greater at the total population level and in four of t he five individual populations. Overall soil seed (but not surface pla nt) homozygosity was significantly greater than predicted by Hardy-Wei nberg expectations at the total and individual population levels. Alth ough F-st estimates revealed similarly small but significant genetic d ivergence within each life-history stage, estimates of coancestry show ed that fine-scale (0.5-2 m) genetic correlations among the surface pl ant genotypes were roughly twice those of soil seed genotypes. An unwe ighted pair group method with arithmetic mean cluster analysis indicat ed that in the two geographically closest sites, the surface plants we re slightly more genetically similar to each other than to their own r espective seed banks. We also found weak and/or negative demographic a ssociations between Lesquerella soil seed and surface plant densities within each of the five sites. We discuss the difficulties involved wi th sampling and genetically comparing these two life-history stages.