Differences in Flowering Phenology Are Likely Not the Product of Competition for Pollination in Clarkia Communities
Differences in Flowering Phenology Are Likely Not the Product of Competition for Pollination in Clarkia Communities
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DOI：
10.1086/705607
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发表时间：
2019-11-01
影响因子：
2.3
通讯作者：
Geber, Monica A.
中科院分区：
文献类型：
--
作者：
Eisen, Katherine E.;Campbell, Diane R.;Geber, Monica A.
研究的前提。共存物种之间的开花物候交错通常被解释为授粉竞争的产物，但种间开花时间差异可能是由促进性、中性或竞争性相互作用造成的。开花时间的种间差异可能因群落密度和物种组成而异。方法。为了确定错开的开花时间是否适合克兰河峡谷（Kern County， CA）克兰河峡谷（Kern County， CA）克兰河峡谷（Kern County， CA）克兰河峡谷的克兰河（onagracae）克兰河（Clarkia）群落，我们利用盆栽植物对两种克兰河（Clarkia） （C. speciosa和C. xantiana）的开花时间进行了调节。为了确定开花时间差异的影响是否会随着群落环境的变化而变化，我们在3种不同类型的群落中进行了实验，这些群落包括0种克拉氏菌（空白群落）、早花物种和早花物种以及一个晚花焦点物种（混合群落）。关键的结果。在所有群落类型和两个花期，斑克拉氏菌的种子数量相当。各群落类型中，黄天麻在开花前期的结实率较高。在早花期克氏菌群落中，传粉者对C. speciosa的访问量最高，而对C. xantiana的访问量在花期和群落类型之间没有差异。在不同群落和不同花期，黄天麻种子结实率与立地花密度呈正相关。结论。开花时间对黄天麻的繁殖成功率没有影响，而开花时间对黄天麻的繁殖成功率没有影响。这些模式表明，这两个物种的晚开花很可能不是种间传粉者竞争的结果，而可能是非传粉媒介选择的结果。此外，我们的研究结果表明，群落密度可以影响开花策略的生态后果，进而影响开花物候的演变。
Premise of research. Staggered flowering phenologies among co-occurring species have often been interpreted as the product of competition for pollination, but interspecific flowering time differences could result from facilitative, neutral, or competitive interactions. The consequences of interspecific differences in flowering time may vary with the density and species composition of a community. Methodology. To determine whether staggered flowering times are adaptive in communities of Clarkia (Onagraceae) in the Kern River Canyon (Kern County, CA), we used potted plants to manipulate the flowering time of two species of Clarkia (C. speciosa and C. xantiana) that flower later than two other species of Clarkia. To determine whether the consequences of flowering time differences change with community context, we conducted this experiment at three types of communities that contained either zero Clarkia species (blank communities), the early-flowering species, or the early-flowering species and one late-flowering focal species (mixed communities). Pivotal results. Clarkia speciosa set an equivalent amount of seeds across all community types and both flowering periods. In contrast, seed set of C. xantiana was higher during the early-flowering period in all community types. Pollinator visitation to C. speciosa was highest in early-flowering Clarkia communities, while visitation to C. xantiana did not vary across flowering periods or community types. Across communities and flowering periods, seed set of C. xantiana was positively correlated with site floral density. Conclusions. Flowering later is not adaptive for C. xantiana, while flowering time may have no effect on the reproductive success of C. speciosa. These patterns indicate that later flowering in both species is likely not a result of interspecific competition for pollinators and may result from non-pollinator-mediated selection. In addition, our results indicate that the density of a community can affect the ecological consequences of a flowering strategy and, by extension, the evolution of flowering phenology.