02411nas a2200193   4500008004100000020001400041245018400055210006900239260001200308300001600320490000700336520162600343100001401969700001401983700001901997700001502016700002402031856016202055       1997                        eng d  a0002-912200aThe spatial genetic structure of cytoplasmic (cpDNA) and nuclear (allozyme) markers within and among populations of the gynodioecious Thymus vulgaris (Labiatae) in southern France0 aspatial genetic structure of cytoplasmic cpDNA and nuclear alloz  c1997///  a1675 - 16840 v843 aRecent advances in molecular biology have allowed the development of techniques to contrast spatial differentiation in nuclear and cytoplasmic genes and thus provide important data on relative levels of gene flow by pollen and seed in higher plants. In this paper, we compare the spatial structure of nuclear (allozymes) and cytoplasmic (cpDNA) genes among populations of the gynodioecious Thymus vulgaris in southern France. Based on a combination of three restriction enzymes (CfoI, EcoRV, and PstI), eight chlorotypes (combination of three restriction enzyme patterns revealed by Southern hybridization of Beta vulgaris cpDNA) were identified in the 13 studied populations. One chlorotype was particularly abundant and was detected in nearly all populations. Only one chlorotype was specific to a single population. Up to four different chlorotypes were observed in some populations. An F sub(ST) of 0.238 (P < 0.002) for cpDNA haplotypes indicates spatial structure of cytoplasmic genes among the studied populations. Similar patterns were found within a single young population (CAB) structured in patches and surrounded by a continuous cover of T. vulgaris where the F sub(ST) is 0.546 (P < 0.002). No significant correlation between sex and chlorotype nor between cpDNA diversity and female frequency was detected. Allozyme markers showed markedly less spatial structure (F sub(ST) = 0.021 among populations and 0.019 in the CAB population, P < 0.001). This difference between cpDNA and nuclear allozyme markers suggests that pollen dispersal is more important than seed dispersal both among and within populations1 aCuguen, J1 aCouvet, D1 aThompson, J, D1 aTarayre, M1 aSaumitou-Laprade, P  uhttp://muse.lib.auth.gr:9797/com/csa/?MuseHost=www-mi2.csa.com&MuseFirst=1&id=2&recnum=1&SID=720ce478dc2df80d779b696384a1418e&MusePath=/ids70/view_record.php