Parker Matthew A
Department of Biology, Whitman Laboratory, University of Chicago, 915 E. 57th Street, 60637, Chicago, IL, USA.
Oecologia. 1986 May;69(2):253-259. doi: 10.1007/BF00377631.
Demographic analyses in two natural populations of the annual legume Amphicarpaea bracteate examined whether variation in attack by the host-specific fungal pathogen Synchytrium decipiens was associated with variation in the reproductive success of individual plants. In both populations, fungal infection early in life was significantly associated with reduced seedling growth rates. Laboratory inoculation experiments confirmed that S. decipiens infection had a negative impact on plant growth. The laboratory experiments further indicated that there was significant variation among the progenies of different plant genotypes in the degree of growth reduction caused by pathogen attack. Prereproductive mortality rates in natural environments were significantly higher for plants with infection intensities above the median; for the two populations studied, heavily infected plants had 3.8 and 12 gimes higher death rates compared with low infection plants. Among surviving plants, fungal infection intensity was significantly negatively correlated with total seed biomass in both populations. As a result of these associations between plant survivorship, fecundity, and fungal infection, lifetime relative fitness within both plant populations was strongly negatively correlated with the intensity of S. decipiens infection. These results demonstrate the existence of consistent natural selection for increased resistance to pathogen attack in this plant species.
对一年生豆科植物两型豆的两个自然种群进行的种群统计学分析，研究了宿主特异性真菌病原体欺骗集壶菌的侵染变异是否与单株植物繁殖成功率的变异相关。在这两个种群中，生命早期的真菌感染与幼苗生长速率降低显著相关。实验室接种实验证实，欺骗集壶菌的侵染对植物生长有负面影响。实验室实验进一步表明，不同植物基因型的后代在病原体攻击导致的生长降低程度上存在显著差异。在自然环境中，感染强度高于中位数的植物的繁殖前死亡率显著更高；对于所研究的两个种群，与低感染植物相比，重度感染植物的死亡率分别高3.8倍和12倍。在存活植物中，两个种群的真菌感染强度与种子总生物量均显著负相关。由于植物存活率、繁殖力和真菌感染之间存在这些关联，两个植物种群内的终生相对适合度与欺骗集壶菌的感染强度均呈强烈负相关。这些结果证明了在该植物物种中存在针对增强病原体攻击抗性的一致自然选择。
