Contrasting soil-texture niches facilitate coexistence of two congeneric plants that differ in competitive ability
Contrasting soil-texture niches facilitate coexistence of two congeneric plants that differ in competitive ability
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DOI：
10.1093/aobpla/plx066
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发表时间：
2017-01-01
期刊：
影响因子：
2.9
通讯作者：
Geber, Monica A.
中科院分区：
文献类型：
--
作者：
Eckhart, Vincent M.;Howland, Madeline R.;Geber, Monica A.
进化上的近亲是否能共存，预计取决于生态位上的进化分歧相对于竞争能力的分歧。我们调查了植物物种对土壤质地的反应如何影响共存，通过分析冬季一年生植物Clarkia speciosa ssp.的分布、出苗和表现以及竞争能力。polyantha和C.桑蒂亚纳湾xantiana。景观调查表明，该物种与土壤质地有明显的关联，C。speciosa的存在与细土和C.与粗糙的土壤相关的xantiana。在种群存在的规模上，物种共同出现的频率比随机出现的频率低。在小规模的网站内，他们共同出现，每个物种与其他负相关。Clarkia xantiana的存在和/或密度也呈正相关，粗糙的土壤质地和陡峭，向极的斜坡，这表明限制水的可用性。实验室实验，不同的基质质地和施加干旱揭示了对比物种的基本生态位在种子和幼苗阶段。在粗基质中，C. xantiana幼苗的出苗率比C. speciosa和C. speciosa，种子埋深0.5cm时萌发。美丽克拉克花幼苗具有上级耐旱性，不依赖于基质。在人工基质中的响应面实验中估计的竞争系数预测了C. speciosa，C. xantiana在粗基质中，与精细基质中的竞争结果的可能的创始人控制。物种对土壤质地反应的差异会产生空间隔离，这可能有利于共存，尽管竞争能力差异会反对它。
Whether close evolutionary relatives can coexist is expected to depend on evolutionary divergence in niches relative to divergence in competitive abilities. We investigated how plant species' responses to soil texture might affect coexistence by analysing distributions, seedling emergence and performance, and competitive abilities of the winter annuals Clarkia speciosa ssp. polyantha and C. xantiana ssp. xantiana. A landscape survey showed that the species have distinct associations with soil texture, C. speciosa presence correlating with fine soil and C. xantiana correlating with coarse soil. At the scale of population presences, the species co-occur less often than would be expected at random. On small scales within sites where they do co-occur, each species was negatively associated with the other. Clarkia xantiana presence and/or density also correlated positively with coarse soil texture and steep, poleward slopes, suggesting limitation by water availability. Lab experiments that varied substrate texture and imposed drought revealed contrasting species' fundamental niches at the seed and seedling stages. In coarse substrates, C. xantiana seedlings emerged at several-fold higher rates than C. speciosa, and, unlike C. speciosa, emerged when seeds were buried 0.5 cm. Clarkia speciosa seedlings had superior drought tolerance, independent of substrate. Competition coefficients estimated in a response surface experiment in artificial substrates predicted competitive exclusion of C. speciosa by C. xantiana in coarse substrate, with possible founder control of competitive outcome in fine substrate. Species' differences in responses to soil texture generate spatial segregation that likely facilitates coexistence, despite competitive ability differences that oppose it.