Search

The current study aimed to determine the effect of increased diet density through increasing dietary fat level on growth performance and energy balance characteristics of broiler chickens during the first week of life. The effects of diet density on energy and nitrogen metabolism were studied using a dose response design that comprised 5 dietary fat inclusion levels (3.5, 7.0, 10.5, 14.0, and 17.0%) while maintaining a constant digestible amino acid to energy ratio. Chickens were housed in open circuit climate respiration chambers. Preplanned contrasts were used to determine significant linear and quadratic relationships with diet density. Feed intake and BW gain linearly decreased and gain to feed ratio increased (P

La diversidad genética de los arbustos de Cotoneaster franchetii es similar entre los rangos de distribución nativo y no nativo. Debido al efecto fundador comúnmente se asume que las plantas tienen mayor diversidad genética en su rango nativo que en las áreas donde fueron introducidos. Sin embargo, pocos estudios han probado este supuesto incluyendo la comparación entre los rangos nativos y no nativos. Nosotros analizamos marcadores de AFLP en 149 individuos de Cotoneaster franchetii pertenecientes a cinco poblaciones nativas (China) y cinco no nativas (Argentina) donde este arbusto invade exitosamente diferentes ambientes, y forma rodales extensos y monoespecíficos. Además comparamos los estimadores de diversidad genética y evaluamos la diferenciación genética entre las poblaciones examinando los valores de Fst y realizando un ACoP, un AMOVA y una prueba de Mantel. No se encontró evidencia de diversidad genética reducida en las poblaciones no nativas, mientras que el ACoP reveló dos grupos distintos, reflejando sus orígenes argentinos y chinos. Diez individuos de dos de las poblaciones chinas fueron la excepción, debido a que se agruparon dentro de las poblaciones argentinas, apoyando la idea de introducciones múltiples desde China hacia Argentina. It is commonly assumed that plants have more genetic diversity in their native range than in areas where they have been introduced due to founder effects. However, few studies have proven this assumption and included the comparison between non-native and native ranges. We analyzed AFLP fingerprint patterns of 149 individuals from five native (China) and five non-native (Argentina) populations of Cotoneaster franchetii, a shrub which successfully invades different habitats and forms extensive monospecific stands. We compared genetic diversity estimates and assessed genetic differentiation among populations by inspecting FST values and conducting a PCoA, an AMOVA and a Mantel test. No evidence was found for reduced genetic diversity in non-native populations while the PCoA revealed two distinct groups, reflecting their Chinese and Argentine origin. The exceptions were ten individuals from two Chinese populations that clustered within the Argentine populations, supporting the idea of multiple introductions from China to Argentina. Fil: Lett, Irene. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Ecología y Recursos Naturales Renovables; Argentina Fil: Hensen, Isabell. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden; Alemania. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Alemania Fil: Hirsh, Heidi. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden; Alemania. Stellenbosch University, Centre for Invasion Biology, Department of Botany and Zoology; Sudáfrica Fil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina

Aim. To assess the effects of altitude and historic and recent forest fragmentation on the genetic diversity and structure of the wind-pollinated tropical tree line species Polylepis incana. Location. One of the highest mountain forest regions of the world, located in the Eastern Cordillera of the Ecuadorian Andes. Methods. We compared genetic diversity and structure of adult trees with those of seedlings (n = 118 in both cases) in nine forest stands spanning an altitudinal gradient from 3500 to 4100 m a.s.l. using amplified fragment length polymorphisms(AFLPs). Genetic diversity was calculated as percentage of polymorphic bands (P) and Nei?s expected heterozygosity (He); genetic differentiation was assessed using analysis of molecular variance, FST statistics and Bayesian cluster analysis. Results. Estimates of genetic diversity at the population level were significantly lower in seedlings than in adults. Genetic diversity (He-value) was, in both cases, negatively correlated to altitude and positively correlated to population size in the seedlings. Genetic differentiation of the seedlings was approximately as high (fST = 0.298) as that of the adults (fST = 0.307), and geographical differentiation was clearly reflected in both AFLP profiles, with mountain ridges acting as barriers to gene flow. Main conclusions Our study provides evidence of a historic upslope migration of P. incana in central Ecuador. In addition, it highlights the detrimental effects of unexpectedly strong genetic isolation, both recent and historical, particularly for our wind-pollinated species where the distance between forest stands was less than 25 km. We therefore additionally propose that in habitats with pronounced highmountain landscape structures, gene flow may be hampered to such an extent that species have a more pronounced sensitivity to habitat fragmentation, even among populations of wind-pollinated trees. Fil: Hensen, Isabell. Martin Luther University of Halle‐Wittenberg; Alemania Fil: Cierjacks, Arne. Technishe Universitat Berlin; Alemania Fil: Hirsch, Heidi. Martin Luther University of Halle‐Wittenberg; Alemania Fil: Kessler, Michael. Universitat Zurich; Suiza Fil: Romoleroux, Katya. Pontificia Universidad Catolica del Ecuador; Ecuador Fil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina Fil: Wesche, Karsten. Senckenberg Museum of Natural History Görlitz; Alemania

In der stark fragmentierten Porphyrkuppenlandschaft nordwestlich von Halle (Sachsen-Anhalt) wurden vegetationsdynamische Prozesse auf kleinflächigen xerothermen Standorten (Kuppen unter 500 qm) unterschiedlichen Alters analysiert. Die Grundlage bildeten detaillierte, flächengenaue vegetationskundliche Erhebungen aus den Jahren 1992 und 2000. Hierbei konnte festgestellt werden, dass die Individuendichte der meisten der insgesamt 216 Arten Schwankungen aufwies, wobei nur für einen geringen Teil der Arten eine deutliche Ab- bzw. Zunahme (Stetigkeitsschwankungen > 10 %) registriert wurde. Während vorwiegend ruderale Arten zurückgingen, erhöhte sich die Stetigkeit einer Reihe von Arten der Trocken- und Halbtrockenrasen. Die floristische Ähnlichkeit der Kuppen zwischen den beiden Untersuchungsjahren lag im Mittel bei 62 %. Dies schlug sich z.T. auch in einem Umbau der insgesamt 28 Pflanzengesellschaften nieder. Dabei zeigten die xerothermen Trocken- und Halbtrockenrasen eine höhere Stabilität, während die stärker ruderalisierten Gesellschaften eine hohe Dynamik aufwiesen und sich auf verschiedenen Wegen zur Festuca rupicola-Gesellschaft und zum Thymo-Festucetum umbildeten. Unter den gegebenen standörtlichen Verhältnissen stellen diese beiden Gesellschaften vorläufige Endstadien der Vegetationsentwicklung dar. Dieser Trend zur Entwicklung von Trocken- und Halbtrockenrasen auf den kleinflächigen Porphyrkuppen spiegelt sich auch in der Zusammensetzung der Diasporenbank wider. Kleinflächige Porphyrkuppen sind nicht durch Pufferzonen vom angrenzenden Umland abgeschirmt. Daher stellen Störungen, die vorwiegend durch die Art und Weise der Bewirtschaftung gekennzeichnet sind, einen entscheidenden Einflussfaktor für die Vegetationsentwicklung dar. Je geringer das Ausmaß der jährlichen Störungen ist, desto eher tendiert die Entwicklung zu naturnäheren sowie stabileren Trocken- und Halbtrockenrasen-Gesellschaften. Dabei kann sich die Form der Umlandbewirtschaftung jährlich ändern bzw. können außergewöhnliche Ereignisse auftreten. Aus diesem Grund unterliegen die Artenzusammensetzung sowie die Vegetationsentwicklung auf den kleinflächigen Porphyrkuppen einer großen Zufälligkeit. Dies erklärt, dass die Zusammenhänge zwischen Artenzahl und Gemeinschaftskoeffizienten in Abhängigkeit von der Flächengröße der Kuppen nur eine geringe Korrelation aufweisen. Aus naturschutzfachlicher Sicht besitzen die kleinen Porphyrkuppen jedoch ein Potential an gefährdeten und geschützten Arten, welches hinsichtlich Artenzahl sowie Individuendichte mit dem Alter der Kuppen zunimmt. Somit können sie Trittsteinfunktionen in der stark fragmentierten Landschaft des unteren Saaletals einnehmen. Vegetation-dynamic processes on small outcrops of different origin were investigated in the fragmentated landscape with porphyry outcrops in the lower valley of the river Saale. Relevés from 1992 and 2000 were used as a database. The analysis showed that the abundance of most species (216) had changed over this time but that the constancy of only a few species increased or decreased more than 10%. Ruderal species mostly declined, and species of dry and semi-dry grasslands gained. The floristical similarity of the outcrop samples in the two years was 62 % on average. This also included some restructuring of the 28 plant communities. Whereas the xerothermic dry and semi-dry grasslands were rather stable, the more ruderal communities appeared highly dynamic and changed into a Festuca rupicola community and into the Thymo-Festucetum cinereae. Due to the special site conditions these two communities represent provisional final stages of the vegetation succession. A tendency for the development of dry and semi-dry grasslands was also reflected by the seed-bank composition. The small outcrops are not protected by buffer zones against influences from the surrounding landscape. Disturbances caused by agricultural land use are the main factors influencing the vegetation dynamics here. Vegetation development tended toward nearly natural, more stable communities of dry and semi-dry grasslands under less disturbance. Agricultural management, however, can change every year, and unexpected events can happen. For this reason the vegetation development of the small porphyry outcrops is characterisied by a very high stochasticity. This also explains the low correlation between the number of species and community coefficient with the size of the outcrops. The small outcrops have the potential to conserve endangered and protected plant species, the number and abundance of which increased with the age of the outcrops. Hence these locations can serve as stepping stones in the fragmentated landscape of the Saale valley.