02289nas a2200265   4500008004100000245013400041210006900175300001200244490000700256520147500263653001401738653002801752653001701780653001801797653002001815653001201835100002601847700003001873700001501903700001601918700001301934700002101947700001201968856004301980       2005                        eng d00aGene flow and hybridisation in a mixed oak forest (Quercus pyrenaica Willd. and Quercus petraea (Matts.) Liebl.) in central Spain0 aGene flow and hybridisation in a mixed oak forest Quercus pyrena  a457-4650 v953 aOaks are long-standing models for the study of gene flow and hybridisation. Temperate (Quercus petraea) and sub-Mediterranean (Quercus pyrenaica) oaks coexist in central Spain, showing remarkable differences in population size and structure. Q. petraea has a scattered distribution in central Spain, where it is at one of the southernmost limits of its range, and forms low-density stands; in contrast, Q. pyrenaica is widespread in the region. We selected a mixed population of the two species (approx13 ha, 176 adults and 96 saplings) to compare the patterns of gene flow within each species and the extent of introgression between them. Using five nuclear microsatellite markers, we performed a parentage analysis and found considerable immigration from outside the stand (approx38% for Q. petraea and approx34% for Q. pyrenaica), and estimated average seed-dispersal distances of 42 and 14 m for Q. petraea and Q. pyrenaica, respectively. Introgression between species was also estimated using our microsatellite battery. First, we developed a multivariate discriminant approach and, second, we compared our results with a widely used clustering method (STRUCTURE). Both analyses were consistent with a low level of introgression between Q. petraea and Q. pyrenaica. Indeed, only 15 adult trees, approx8.5%, were identified as putative hybrids when both methods of analysis were combined. Hybrids may be most common in contact zones due merely to physical proximity.10agene flow10agenetic differentiation10ahybrid zones10aintrogression10amicrosatellites10aQuercus1 aValbuena-Carabana, M.1 aGonzalez-Martinez, S., C.1 aSork, V.L.1 aCollada, C.1 aSOTO, A.1 aGoicoechea, P.G.1 aGil, L.  uhttps://quercus.myspecies.info/node/3602524nas a2200193   4500008004100000245012000041210006900161260000900230300001400239490000700253520193500260100000502195700001602200700001302216700001902229700001202248700001502260856005502275       2009                        eng d00aElucidating the role of genetic drift and natural selection in cork oak differentiation regarding drought tolerance0 aElucidating the role of genetic drift and natural selection in c  c2009  a3803-38150 v183 aDrought is the main selection agent in Mediterranean ecosystems and it has been suggested as an important evolutionary force responsible for population diversification in these types of environments. However, population divergence in quantitative traits can be driven by either natural selection, genetic drift or both. To investigate the roles of these forces on among-population divergence in ecophysiological traits related to drought tolerance (carbon isotope discrimination, specific leaf area, leaf size and leaf nitrogen content), we compared molecular and quantitative genetic differentiation in a common garden experiment including thirteen cork oak (Quercus suber L.) populations across a gradient of rainfall and temperature. Population differentiation for height, specific leaf area, leaf size and nitrogen leaf content measured during a dry year far exceeded the molecular differentiation measured by six nuclear microsatellites. Populations from dry-cool sites showed the lowest nitrogen leaf content and the smallest and thickest leaves contrasting with those from humid-warm sites. These results suggest (i) these traits are subjected to divergence selection and (ii) the genetic differences among populations are partly due to climate adaptation. By contrast, the low among-population divergence found in basal diameter, annual growth and carbon isotopic discrimination (a surrogate for water use efficiency) suggests low or no divergence selection for these traits. Among-population differentiation for neutral markers was not a good predictor for differentiation regarding the quantitative traits studied here, except for leaf size. The correlation observed between the genetic differentiation for leaf size and that for molecular markers was exclusively due to the association between leaf size and the microsatellite QpZAG46, which suggests a possible linkage between QpZAG46 and genes encoding for leaf size.1 a1 aLORENZO, Z.1 aSOTO, A.1 aVALLADARES, F.1 aGil, L.1 aARANDA, I.  uhttp://dx.doi.org/10.1111/j.1365-294X.2009.04317.x