从幼苗到成树：生活史和权衡策略塑造了基础物种的生长、防御和繁殖
Growing up aspen: ontogeny and trade-offs shape growth, defence and reproduction in a foundation species.
机构信息
Department of Entomology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI, USA.
Department of Natural and Behavioral Sciences, University of Maine at Ft. Kent, 23 University Drive, Fort Kent, ME, USA.
出版信息
Ann Bot. 2021 Mar 24;127(4):505-517. doi: 10.1093/aob/mcaa070.
BACKGROUND AND AIMS
Intraspecific variation in foundation species of forest ecosystems can shape community and ecosystem properties, particularly when that variation has a genetic basis. Traits mediating interactions with other species are predicted by simple allocation models to follow ontogenetic patterns that are rarely studied in trees. The aim of this research was to identify the roles of genotype, ontogeny and genotypic trade-offs shaping growth, defence and reproduction in aspen.
METHODS
We established a common garden replicating >500 aspen genets in Wisconsin, USA. Trees were measured through the juvenile period into the onset of reproduction, for growth, defence chemistry (phenolic glycosides and condensed tannins), nitrogen, extrafloral nectaries, leaf morphology (specific leaf area), flower production and foliar herbivory and disease. We also assayed the TOZ19 sex marker and heterozygosity at ten microsatellite loci.
KEY RESULTS
We found high levels of genotypic variation for all traits, and high heritabilities for both the traits and their ontogenetic trajectories. Ontogeny strongly shaped intraspecific variation, and trade-offs among growth, defence and reproduction supported some predictions while contradicting others. Both direct resistance (chemical defence) and indirect defence (extrafloral nectaries) declined during the juvenile stage, prior to the onset of reproduction. Reproduction was higher in trees that were larger, male and had higher individual heterozygosity. Growth was diminished by genotypic allocation to both direct and indirect defence as well as to reproduction, but we found no evidence of trade-offs between defence and reproduction.
CONCLUSIONS
Key traits affecting the ecological communities of aspen have high levels of genotypic variation and heritability, strong patterns of ontogeny and clear trade-offs among growth, defence and reproduction. The architecture of aspen's community genetics - its ontogeny, trade-offs and especially its great variability - is shaped by both its broad range and the diverse community of associates, and in turn further fosters that diversity.
背景与目的
森林生态系统基础物种的种内变异可以塑造群落和生态系统的特性，尤其是当这种变异具有遗传基础时。介导与其他物种相互作用的特征可根据简单的分配模型来预测，这些模型很少在树木中研究其个体发育模式。本研究的目的是确定基因型、个体发育和基因型权衡在白杨生长、防御和繁殖中的作用。
方法
我们在美国威斯康星州建立了一个共同的花园，复制了超过 500 个白杨基因。通过幼年期到繁殖期，对树木的生长、防御化学物质（酚糖苷和缩合单宁）、氮、叶外蜜腺、叶片形态（比叶面积）、花的产量以及叶片虫害和疾病进行了测量。我们还检测了 TOZ19 性别标记和十个微卫星位点的杂合度。
主要结果
我们发现所有性状的基因型变异水平都很高，性状及其个体发育轨迹的遗传力也很高。个体发育强烈塑造了种内变异，而生长、防御和繁殖之间的权衡关系支持了一些预测，同时也反驳了其他预测。直接防御（化学防御）和间接防御（叶外蜜腺）在繁殖期之前的幼年期都下降了。在树木中，体型较大、雄性和个体杂合度较高的树木繁殖能力较高。基因型对直接和间接防御以及繁殖的分配都会降低生长，但我们没有发现防御和繁殖之间存在权衡关系的证据。
结论
影响白杨生态群落的关键特征具有高水平的基因型变异和遗传力、强烈的个体发育模式以及生长、防御和繁殖之间的明显权衡。白杨社区遗传学的结构——它的个体发育、权衡以及特别是它的巨大变异性——是由其广泛的范围和多样化的伙伴社区共同塑造的，并反过来进一步促进了这种多样性。
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