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GUILLERMO PÉREZ BERNARD SLIPPERS BRENDA D. WINGFIELD GAVIN C. HUNTER MICHAEL J. WINGFIELD 《Molecular ecology》2010,19(9):1801-1813
Sexual reproduction in fungi involves either a single individual (selfing) or two individuals (outcrossing). To investigate the roles that these two strategies play in the establishment of an invasive alien pathogen, the Eucalyptus leaf‐infecting fungus, Teratosphaeria (Mycosphaerella) nubilosa was studied. Specifically, the genetic diversity of the pathogen was investigated at micro and macrospatial scales. Interestingly, while data obtained at microspatial scales show clearly that selfing is the main reproductive strategy, at macrospatial scales the population genetic structure was consistent with a genetically outcrossing organism. Additional analyses were performed to explore these apparently discordant results at different spatial scales and to quantify the contribution of selfing vs. outcrossing to the genotypic diversity. The results clearly show that the fungus has a mixed mating strategy. While selfing is the predominant form of mating, outcrosses must have occurred in the pathogen that increased the genotypic diversity of the fungus over time. This mating strategy, coupled with the high levels of geneflow between distant populations of the pathogen, has created an even distribution of maximum diversity from the smallest (leaf) to largest scales (>500 km), which will make breeding for resistance difficult. These data illustrate the evolutionary potential and danger of the introduction of multiple genotypes of a potentially outcrossing pathogen, especially when it has a high dispersal potential. 相似文献
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MYRA C. HALL PETER STILING† DANIEL C. MOON‡ BERT G. DRAKE§ MARK D. HUNTER 《Global Change Biology》2006,12(3):568-577
Decomposition of Quercus myrtifolia leaf litter in a Florida scrub oak community was followed for 3 years in two separate experiments. In the first experiment, we examined the effects CO2 and herbivore damage on litter quality and subsequent decomposition. Undamaged, chewed and mined litter generated under ambient and elevated (ambient+350 ppm V) CO2 was allowed to decompose under ambient conditions for 3 years. Initial litter chemistry indicated that CO2 levels had minor effects on litter quality. Litter damaged by leaf miners had higher initial concentrations of condensed tannins and nitrogen (N) and lower concentrations of hemicellulose and C : N ratios compared with undamaged and chewed litter. Despite variation in litter quality associated with CO2, herbivory, and their interaction, there was no subsequent effect on rates of decomposition under ambient atmospheric conditions. In the second experiment, we examined the effects of source (ambient and elevated) of litter and decomposition site (ambient and elevated) on litter decomposition and N dynamics. Litter was not separated by damage type. The litter from both elevated and ambient CO2 was then decomposed in both elevated and ambient CO2 chambers. Initial litter chemistry indicated that concentrations of carbon (C), hemicellulose, and lignin were higher in litter from elevated than ambient CO2 chambers. Despite differences in C and fiber concentrations, litter from ambient and elevated CO2 decomposed at comparable rates. However, the atmosphere in which the decomposition took place resulted in significant differences in rates of decomposition. Litter decomposing under elevated CO2 decomposed more rapidly than litter under ambient CO2, and exhibited higher rates of mineral N accumulation. The results suggest that the atmospheric conditions during the decomposition process have a greater impact on rates of decomposition and N cycling than do the atmospheric conditions under which the foliage was produced. 相似文献
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