Morphological differentiation supports the genetic pattern of the geographic structure of Juniperus thurifera (Cupressaceae)

12 p., mapas, tablas, gráf.Juniperus thurifera is an important component of woodland communities of dry sites within the West Mediterranean region and is characterised by a strongly disjunctive geographic range. Two subspecies were recognised, subsp. thurifera in Europe and subsp. africana in Africa. The aim of the study was the comparison of phenetic diversity to the pattern of AFLP geographic differentiation of the species described in the literature. The examination of phenetic diversity was based on the biometrical analysis of 17 populations using 12 morphological characters of cone and seed. The differences among populations were analysed using Student’s t test, analysis of discrimination, UPGMA agglomeration and hierarchical analysis of variance. The majority of morphological characters differentiated at a statistically significant level between populations and between J. thurifera subsp. thurifera and subsp. africana. Three groups of populations were detected using multivariate statistical analyses. The first, well separated, is subsp. africana, while the following two concern subsp. thurifera. The morphological differentiation of populations appeared similar to that described on the AFLP. The Gibraltar Straight appeared to be the most important barrier.Funding the work was partly sponsored by the Institute of Dendrology of the Polish Academy of Sciences. The collection of material was made possible due to the bilateral cooperation of the Polish Academy of Sciences with the Spanish National Research Council "Consejo Superior de Investigaciones Científicas".Peer reviewe

Effect of geographic range discontinuity on taxonomic differentiation of Abies cilicica

Three populations of Abies cilicica subsp. isaurica and four of A. cilicica subsp. cilicica were analyzed using 35 morphological and anatomical needle characters with the implementation of multivariate statistical methods to verify the differences between subspecies. Moreover, the possible geographic differentiation of A. cilicica subsp. cilicica populations from the East Taurus and Lebanon Mountains was examined. Abies cilicica subsp. isaurica has been distinguished from A. cilicica subsp. cilicica by its glabrous young shoots and resinous buds. We detected that needles of A. cilicica subsp. isaurica are longer, broader and thicker, with a higher number of stomata rows, and larger cells of the epidermis, hypodermis and endodermis than A. cilicica subsp. cilicica. Additionally, A. cilicica subsp. isaurica needles have frequently rounded to obtuse-acute apex and resinous canals positioned more centrally inside the mesophyll than needles of A. cilicica subsp. cilicica. This indicates that a set of most of the tested needle characters can be used to distinguish the subspecies; however, any of characters enable that when used separately. Morphological and anatomical distinctiveness between these two taxa justify their recognition at the subspecies rank. Additionally, the populations of A. cilicica subsp. cilicica from the East Taurus and Lebanon are morphologically different. This geographic differentiation of populations is congruent with results provided by genetic analyses of nuclear microsatellites markers (nSSR)

Taxus data

Microsatellite genotypes of trees and seedlings, and field measurements of Taxus baccata trees in 10 populations in Poland

The greater growth rate of male over female of the dioecious tree Juniperus thurifera only in worse habitat conditions

Dioecy is a mating system in which a greater reproductive effort has been observed in one sex than the other. This is expressed in differences between the sexes in growth rate and spatial segregation. The spatial structure of Juniperus thurifera subsp. thurifera and Juniperus communis subsp. communis and growth rate of tree-ring width of J. thurifera were tested in different habitat conditions in Santo Domingo de Silos in northern Spain. We analyzed junipers growing on the eastern slope, with better habitat conditions, and the western, with poorer habitat conditions. The studies found that males of J. communis were taller when compared to the females, both on the eastern and the western slope. J. thurifera females were taller on the eastern slope (the better habitat), but shorter on the western slope as compared to males. J. thurifera males and females on the eastern slope had the greater tree-ring width in comparison with those on the western slope. The annual tree–ring width of males dominated over females on both slopes at first, probably from the time of sexual maturation. However, these differences persisted to the end of the analyzed period only on the poorer western slope. The growth rate of females and males after several years was equal on the eastern slope. Spatial segregation has not been shown, probably due to the homogeneity of the habitat on both slopes. Studies have shown that the decrease of growth rate in J. thurifera females can occur only in the poorer habitat conditions.This study was supported by the Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland.Peer Reviewe

Influence of herbivory pressure on the growth rate and needle morphology of Taxus baccata L. juveniles

Damage by herbivore grazing negatively influences the development of subsequent forest generations. Little is known about the long-term impacts of grazing and interactions between grazing and light conditions on sapling growth after the cessation of herbivory impact. In this study, Taxus baccata saplings were grown over a period of four years in artificial shading at 2, 8, 30 and 100% of full sunlight (described as initial light). These saplings were planted in fenced and unfenced plots in a mixed forest in Poland. After six years with no protection from grazing, deer pressure was eliminated by fencing. In this study, we analysed sapling growth and needle morphology five years after deer suppression. Overall, grazing had a negative significant impact on the growth rate and needle morphology of T. baccata saplings. Saplings damaged by herbivores had a height increment approximately one-third that of non-grazed saplings. The grazed yew saplings had a lower needle area and length and a higher specific leaf area (SLA) than non-grazed saplings. Initial and current light conditions did not influence tree growth rates and needle morphology. However, we found positive correlations between sapling height and both leaf area and leaf length and a negative correlation between sapling height and SLA. Browsed yews also had a greater tendency to form polycormic (multi-stemmed) individuals. Lower growth rates, smaller needles and polycormic stems indicate a strategy of “escaping” herbivory pressure even five years after elimination of deer pressure

Photochemistry and Antioxidative Capacity of Female and Male Taxus baccata L. Acclimated to Different Nutritional Environments

In dioecious woody plants, females often make a greater reproductive effort than male individuals at the cost of lower growth rate. We hypothesized that a greater reproductive effort of female compared with male Taxus baccata individuals would be associated with lower female photochemical capacity and higher activity of antioxidant enzymes. Differences between the genders would change seasonally and would be more remarkable under nutrient deficiency. Electron transport rate (ETRmax), saturation photosynthetic photon flux corresponding to maximum electron transport rate (PPFsat), quantum yield of PSII photochemistry at PPFsat (ΦPPFsat), and chlorophyll a fluorescence and activity of antioxidant enzymes were determined in needles of T. baccata female and male individuals growing in the experiment with or without fertilization. The effects of seasonal changes and fertilization treatment on photochemical parameters, photosynthetic pigments concentration, and antioxidant enzymes were more pronounced than the effects of between-sexes differences in reproductive efforts. Results showed that photosynthetic capacity expressed as ETRmax and ΦPPFsat and photosynthetic pigments concentrations decreased and non-photochemical quenching of fluorescence (NPQ) increased under nutrient deficiency. Fertilized individuals were less sensitive to photoinhibition than non-fertilized ones. T. baccata female and male individuals did not differ in photochemical capacity, but females showed higher maximum quantum yield of PSII photochemistry (Fv/Fm) than males. The activity of guaiacol peroxidase (POX) was also higher in female than in male needles. We concluded that larger T. baccata female reproductive effort compared with males was not at the cost of photochemical capacity, but to some extent it could be due to between-sexes differences in ability to protect the photosynthetic apparatus against photoinhibition with antioxidants

Taxus baccata in Morocco: a tree in regression in its southern extreme

12 p., figuras, tablas, gráficos -- Contiene material suplementario -- Este es un artículo open-access distribuido bajo los términos de la licencia Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licenceThe knowledge on chorology of species is basic for biogeographic and ecological studies and for conservation actions. The data on the chorology of Taxus baccata in Morocco have not been studied. The bibliographic resources, herbarium material, unpublished data of several botanists and the authors’ field notes have been reviewed. Two yew populations on Jbel Lakrâa in the Rif and near Bekrit in the Middle Atlas were measured to verify demographic structure and health conditions. The Maxent model of predict­ed habitat based on bioclimatic variables was used to evaluate the potential geographic range of T. baccata. The species occurs in the mountain areas of northern Morocco: in the Rif, the Middle and High Atlas, at altitudes between (500) 1200 and 2000 (2350) m. In the High Atlas, it reaches its southernmost locations within the geographic range. The populations represented by the highest number of individuals are found in the Western Rif and Middle Atlas, while from the High Atlas only single, isolated individuals are known. The yew occurred preferably in forests of Cedrus atlantica, Abies maroccana, groves of Betula fontqueri, Ilex aquifolium and Prunus lusitanica and in riparian forests located in narrow gorges. Seedlings were observed only at single localities. The population of T. baccata in the Rif presented a good health condition with suc­cessful regeneration, while the population in the Middle Atlas was in a much worse state, where only 4–8 m high yews were observed, without natural regeneration. The Maxent model of predicted habitat, based on bioclimatic variables, suggests that T. baccata could occur today in much broader mountainous areas in Morocco, especially in the Rif and Middle Atlas. However, the progressive decline of this species in Morocco indicates the significant importance of other factors on yew distribution, including microsite conditions and human pressure. Taxus baccata in Morocco is in regression at most of its localities and should be treated as a vulnerable species. Measures to ensure the yew’s conservation are needed, especially at its southernmost localities in the High Atlas.The present study was financially supported by the Institute of Dendrology of the Polish Academy of Sciences (under statutory activity).Peer reviewe

Homogenous genetic structure in populations of Taxus baccata with varied proportions of male and female individuals

English yew( L.) is a strictly outcrossing and dioecious species whose populations are small and isolated. It is known that sex ratios may vary in natural populations due to local environmental conditions or stochastic events. However, unbalanced sex ratios may have negative impacts on genetic diversity through enhanced genetic drift and inbreeding. The present study represents one of the first attempts to compare the genetic variation at microsatellite loci within and between populations with different gender proportions. Our results indicated that there were no significant correlations between sex ratio and the extent of genetic variation in different populations. All populations exhibited high levels of genetic diversity. Additionally, the genetic structure was characterized separately in male and female individuals. Statistical analyses of the set estimators describing the genetic structure of male and female individuals of revealed no significant differences between the two groups. Molecular analysis verified that microsatellite nuclear loci neutrality developed for as there were no significant differences in the genetic variation between males and females and no evidence for any outlier loci using coalescent and hierarchical Bayesian simulations. The results demonstrate that ignoring biased sex ratios in populations had no effect on the assessment of genetic differentiation and genetic diversity within and between populations of this species. These results are discussed with regards to the practical application of molecular markers in conservation programs. Taxus baccataT. baccataT. baccata,T. baccat