RESUMEN
Quantifying the effect of pollen dispersal and flowering traits on mating success is essential for understanding evolutionary responses to changing environments and establishing strategies for forest tree breeding. This study examined, quantitatively, the effects of male fecundity, interindividual distance and anisotropic pollen dispersal on the mating success of Scots pine (Pinus sylvestris), utilizing a well-mapped Scots pine seed orchard. Paternity analysis of 1021 seeds sampled from 87 trees representing 28 clones showed that 53% of the seeds had at least one potential pollen parent within the orchard. Pronounced variation in paternal contribution was observed among clones. Variations in pollen production explained up to 78% of the variation in mating success, which was 11.2 times greater for clones producing the largest amount of pollen than for clones producing the least pollen. Mating success also varied with intertree distance and direction, which explained up to 28% of the variance. Fertilization between neighboring trees 2.3 m apart was 2.4 times more frequent than between trees 4.6 m apart, and up to 12.4 times higher for trees downwind of the presumed prevailing wind direction than for upwind trees. The effective number of pollen donors recorded in the seed orchard (12.2) was smaller than the theoretical expectation (19.7). Based on the empirical observations, a mating model that best describes the gene dispersal pattern in clonal seed orchards was constructed.
Asunto(s)
Pinus sylvestris/genética , Polen/genética , Fertilidad/genética , Modelos Genéticos , Polen/fisiología , Reproducción/genética , Semillas/genéticaRESUMEN
Nonrandom patterns of gene dispersal have been identified as possible causes of genetic structuring within populations. Attempts to model these patterns have generally focused solely on the effects of isolation by distance, but the processes involved are more complex than such modeling suggests. Here, we extend considerations of gene dispersal processes beyond simple isolation by distance effects by directly evaluating the effects of kin-structured gene dispersal mediated by the group dispersal of related seeds within fruits (i.e., kin-structured seed dispersal) by birds on genetic structure in Ilex leucoclada, a clonal dioecious shrub. To examine the genetic structure patterns, we established two 30x30 m plots (one with immature soils in old-growth forest and one in secondary forest, designated IM and SC, respectively) with different I. leucoclada stem densities. In these two plots 145 and 510 stems were found, representing 78 and 85 genets, respectively, identified by analyzing their genotypes at eight microsatellite loci. The clonal structure was stronger in the SC plot than in the IM plot. Correlograms of coancestry for genets in both plots exhibited significant, positive, high values in the shortest distance class, indicating the presence of strong genetic structure. However, Sp statistics revealed that the pattern of the genetic structure differed between the plots. In addition, to estimate the family structure within fruits, we sampled forty fruits, in total, from 15 randomly selected plants in the area around the IM and SC plots, and found that 80% of the fruits were multiseeded and 42-100% of the multiseeded fruits contained at least one pair of full sibs. Simulations based on these estimates demonstrated that the group dispersal of related seeds produced through correlated mating both within and across fruits, but not unstructured half-sib dispersal, could generate the observed magnitude and trends of genetic structure found in the IM plot. Furthermore, in addition to kin-structured seed dispersal, isolation by distance processes is also likely to promote genetic substructuring in the SC plot. After discussing possible ecological factors that may have contributed to the observed genetic structure, we contrast our results with those predicted by general isolation by distance models, and propose that kin-structured seed dispersal should promote some evolutionary phenomena, and thus should be incorporated, where appropriate, in models of gene dispersal in natural plant populations.
Asunto(s)
Ilex/genética , Semillas/genética , Simulación por Computador , Frutas/genética , Genotipo , Ilex/embriología , Ilex/fisiología , Repeticiones de Microsatélite , Modelos Genéticos , Densidad de Población , Reproducción/genética , Reproducción/fisiología , Semillas/fisiologíaRESUMEN
We investigated clonal diversity within patches of Ilex leucoclada and genetic variation within and among patches using random amplified polymorphic DNA (RAPD) markers in a 1-ha plot within an old-growth beech forest. We found 38 patches that exhibited a clumped distribution in the middle of the plot. We identified a total of 166 RAPD phenotypes among the 215 stems sampled from 27 patches that were completely within the plot. The population showed high clonal diversity within patches (mean number of genets relative to number of stems = 0.79; mean Simpson's D = 0.89). Variation in RAPD phenotypes among patches was highly significant (PhiST in the molecular variance analysis = 0.316, P < 0.001), indicating genetic differentiation among patches. Pairwise genetic distances, PhiST, among patches did not correlate with geographical distances among patches. The cluster analysis based on the genetic distances showed few clear clusters of patches, indicating no spatial genetic structure among patches. High levels of clonal diversity both within patches and within the population may be explained by multiple founders, seedling recruitment during patch-formation, and somatic mutation. The significant genetic differentiation among patches may be caused by separate founding events and/or kin structuring within patches.
Asunto(s)
Variación Genética/genética , Ilex/genética , Análisis por Conglomerados , Demografía , Japón , Fenotipo , Técnica del ADN Polimorfo Amplificado Aleatorio , ÁrbolesRESUMEN
The effects of food, antibiotics, diclofenac sodium (DS) and methotrexate (MTX) on oral bioavailability (BA) of MTX were examined in rats. Feeding didn't vary the plasma concentrations after intravenous dosing of 0.5 mg/kg MTX, but enhanced those after oral dosing, and the oral BA. The twice daily oral doses of 40 mg/kg neomycin sulfate (NS) or mixed antibiotics (200 mg/kg NS + 200 mg/kg streptomycin sulfate + 200 mg/kg bacitracin) for 5 days didn't influence the plasma concentrations after intravenous dosing of 0.5 mg/kg MTX, but induced the decreased Cmax and the delayed MRT after oral dosing. The plasma concentrations after intravenous or oral dosing of 2.5 mg/kg MTX in rats orally dosed with 1 or 5 mg/kg/day DS for 4 days were similar to those in the control rats, while the pre-treatment of 25 mg/kg/day DS delayed the elimination of MTX but didn't change the oral BA. The plasma concentrations after intravenous or oral dosing of 2.5 mg/kg MTX in rats, which received the intermittent oral doses of 7.5 mg/kg/3 doses/week MTX for 4 weeks, were comparable to those in the control rats, but the daily pre-treatment of 0.2 mg/kg/day MTX for 4 weeks increased the plasma concentrations after oral dosing, and the BA.
Asunto(s)
Antimetabolitos Antineoplásicos/farmacocinética , Metotrexato/farmacocinética , Administración Oral , Animales , Antibacterianos/farmacología , Antiinflamatorios no Esteroideos/farmacología , Antimetabolitos Antineoplásicos/administración & dosificación , Disponibilidad Biológica , Diclofenaco/farmacología , Ayuno , Vaciamiento Gástrico/efectos de los fármacos , Metotrexato/administración & dosificación , Ratas , Ratas Sprague-DawleyRESUMEN
The contributions of incomplete absorption and a first-pass effect to the low bioavailability (BA) of methotrexate (MTX) were evaluated pharmacokinetically in rats and monkeys which respectively have a lower and higher aldehyde oxidase (AO) activity than humans. Plasma concentration profiles of MTX in rats showed linear and nonlinear pharmacokinetics respectively after intravenous (i.v.) and oral dosing of 0.1, 0.5 or 2.5 mg/kg MTX. In rats, most of the dose was excreted as the parent compound into bile and urine after i.v. dosing of 0.5 mg/kg MTX, while the radioactivity was largely eliminated in expired air after oral dosing of 0.5 mg/kg 14C-MTX. Elimination in expired air fell markedly following antibiotics treatment. 7-Hydroxymethotrexate (7-OH-MTX), formed from MTX by AO, was detected in monkey plasma after i.v. and oral dosing of 0.5 mg/kg MTX, but not in rat plasma. The ratio of the cumulative urinary excretion of 7-OH-MTX to MTX in monkeys was higher after oral dosing than after i.v. dosing. The low BA in rats (10% at 0.5 mg/kg) was shown to be mainly due to incomplete absorption, including limited absorption and degradation to 2,4-diamino-N10-methylpteroic acid (DAMPA) and glutamic acid (Glu) by the carboxypeptidase of intestinal bacteria. The low BA in monkeys (5% at 0.5 mg/kg) was shown to be mainly due to the extensive first-pass effect, including metabolism to 7-OH-MTX.