American Journal of Botany最新文献_第3页

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-11-07 DOI: 10.1002/ajb2.70122

Ricardo Gaytan-Legaria, Ken Oyama, Octavio Rojas-Soto, Antonio González-Rodríguez

Premise

Comparative surveys allow us to characterize the influence of specific factors on population genetic diversity and structure. We conducted a comparative phylogeographic study for three Mexican oak species to identify how their climatic niche preferences and breadth may have influenced historical demography and range shifts during Pleistocene climatic oscillations.

Methods

We estimated genetic diversity and structure for Quercus deserticola, Q. glaucoides, and Q. peduncularis. We inferred historical demographic changes using approximate Bayesian computation and used ecological niche models to determine present potential distribution of the species and used past climatic scenarios to estimate range and altitudinal shifts. We also measured the niche breadth of each species and evaluated niche similarity among species.

Results

We identified differences in population history, which we related to the climatic niche of individual species. For Q. deserticola, we inferred a historical bottleneck consistent with the interglacial refugia hypothesis. Quercus glaucoides, which is characterized by a narrow niche breadth, had high levels of genetic structure based on plastid DNA. Quercus peduncularis had high genetic diversity and low structure. We found correlations between niche breadth and values of genetic structure and diversity. Interglacial contraction and glacial expansion in the three species differed in magnitude, with Q. deserticola exhibiting the most drastic contraction during the interglacial.

Conclusions

Mexican oak species responded differently to historical climatic changes since they have distinct distributions in geographic and climatic space. Levels and patterns of genetic variation agreed with the population history of each species inferred using niche modeling.

前提：对比调查使我们能够表征特定因素对群体遗传多样性和遗传结构的影响。我们对三种墨西哥橡树进行了比较系统地理学研究，以确定它们的气候生态位偏好和宽度如何影响更新世气候振荡期间的历史人口和范围变化。方法对荒漠栎、青松和长柄栎进行遗传多样性和结构分析。我们使用近似贝叶斯计算来推断历史人口变化，使用生态位模型来确定物种当前的潜在分布，并使用过去的气候情景来估计范围和高度变化。我们还测量了各物种的生态位宽度和物种间的生态位相似性。结果：我们发现了种群历史的差异，并将其与个体物种的气候生态位联系起来。对于荒漠菌，我们推断出一个与间冰期避难假说一致的历史瓶颈。其生态位宽度较窄，具有较高的质体DNA遗传结构。长柄栎遗传多样性高，结构低。我们发现了生态位宽度与遗传结构和多样性值之间的相关关系。3种植物的间冰期收缩和冰期扩张幅度不同，其中荒漠葵在间冰期收缩幅度最大。结论：墨西哥栎在地理和气候空间上具有不同的分布，对历史气候变化有不同的响应。遗传变异的水平和模式与利用生态位模型推断的每个物种的种群历史一致。

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引用次数: 0

The polyploid continuum and the landscape of polyploid genomic variation 多倍体连续体与多倍体基因组变异景观。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-11-02 DOI: 10.1002/ajb2.70121

Alex D. Twyford, Justin L. Conover, Jeff J. Doyle, Annaliese S. Mason, Douglas E. Soltis, Pamela S. Soltis, Jonathan F. Wendel

Polyploid research has traditionally distinguished between autopolyploids and allopolyploids on the basis of evolutionary origins, modes of inheritance, or chromosomal pairing behavior during meiosis. It has long been recognized, however, that a binary classification does not accurately reflect the complexity and diversity inherent to polyploid organisms, and that these definitions may be inadequate to capture biological diversity. Moreover, inferred conditions at polyploid formation are often obscured by numerous post-polyploidy genomic processes, necessitating a temporal perspective on the meaning of polyploid terminology. In this review, we explore the concept of the “polyploid continuum” and highlight the temporal biological fluidity between the classically recognized alternative end points of autopolyploidy and allopolyploidy. We consider aspects of the polyploid continuum that might meaningfully be evaluated on the basis of genetic variation, including at the sequence, structural, and functional levels. We discuss the utility of the polyploid continuum concept and how it might be visualized as a multidimensional landscape of polyploid diversity that represents a temporal snapshot at any one time. This perspective may better reveal the genesis of polyploid diversity in its many dimensions and provide a framework for understanding the dynamic evolutionary processes that underpin polyploid variation.

多倍体研究历来根据进化起源、遗传模式或减数分裂期间染色体配对行为区分自多倍体和异源多倍体。然而，人们早就认识到，二元分类不能准确地反映多倍体生物固有的复杂性和多样性，而且这些定义可能不足以捕捉生物多样性。此外，多倍体形成的推断条件往往被许多多倍体后基因组过程所掩盖，因此需要对多倍体术语的含义进行时间视角的研究。在这篇综述中，我们探讨了“多倍体连续体”的概念，并强调了经典公认的自多倍体和异源多倍体交替终点之间的时间生物学流动性。我们考虑多倍体连续体的各个方面，这些方面可能在遗传变异的基础上进行有意义的评估，包括序列、结构和功能水平。我们讨论了多倍体连续体概念的效用，以及如何将其可视化为多倍体多样性的多维景观，该景观代表了任何时候的时间快照。这一观点可以更好地揭示多倍体多样性的成因，并为理解多倍体变异的动态进化过程提供一个框架。

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引用次数: 0

Selection of flower color phenotype by contrasting pollinator visual perception in a hybrid zone between two Calceolaria species 通过对比传粉者视觉感知来选择两种天竺葵杂交区的花色表型。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-31 DOI: 10.1002/ajb2.70123

Alicia N. Sérsic, Marco Antonetti, Andrea A. Cocucci

Premise

Colorful traits in biology are often shaped by the perception biases of animals making choices based on color. In angiosperms, flower color diversity may reflect selection by pollinators with distinct visual systems, leading to divergence within or between species. Yet, how these visual biases influence continuous flower color variation—particularly in natural hybrid swarms—remains poorly understood.

Methods

We studied phenotypic selection in a natural hybrid zone between two Calceolaria species with markedly different flower colors, each primarily visited by pollinators with contrasting visual systems (birds vs. bees). We quantified each pollinator's contribution to quantity and quality of pollen deposition on stigmas. Selection mode and strength were estimated for (1) flower color as perceived by each pollinator (via relative photoreceptor stimulation) across three floral parts and (2) color and brightness differences among the three flower parts to assess the degree of visual differentiation among them. Using regression models, we disentangled binomial (whether a flower was visited) from count processes (pollination efficiency) when estimating fitness.

Results

We detected linear selection on color with opposite signs across all flower parts, primarily driven by whether or not flowers were visited. While both pollinators generally favored high chromatic distances, only birds favored high differences in brightness between flower parts.

Conclusions

Birds and bees exerted selection in opposite directions on continuous flower color traits in terms of pollinator-specific perceived color variation. These findings underscore the role of visual biases in driving flower color divergence.

前提：生物学中的色彩特征通常是由动物根据颜色做出选择的感知偏见塑造的。在被子植物中，花的颜色多样性可能反映了具有不同视觉系统的传粉者的选择，导致物种内或物种间的分化。然而，这些视觉偏差如何影响持续的花朵颜色变化，特别是在自然杂交群体中，仍然知之甚少。方法：我们研究了两种花色明显不同的Calceolaria物种之间的自然杂交区表型选择，每种物种主要由具有不同视觉系统的传粉者（鸟类与蜜蜂）访问。我们量化了每种传粉媒介对柱头上花粉沉积数量和质量的贡献。通过对不同传粉者对花的颜色感知（通过相对光感受器刺激）和花的颜色和亮度差异的选择模式和强度进行估算，以评估花的视觉分化程度。使用回归模型，我们在估计适应度时从计数过程（传粉效率）中分离出二项（一朵花是否被访问）。结果：我们检测到颜色的线性选择与相反的符号在所有的花部分，主要是由是否花被访问驱动。虽然这两种传粉者通常都喜欢高颜色距离，但只有鸟类喜欢花部分之间的高亮度差异。结论：在传粉媒介特异性感知颜色变异方面，鸟类和蜜蜂对连续花朵颜色性状进行了相反方向的选择。这些发现强调了视觉偏见在推动花朵颜色差异中的作用。

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引用次数: 0

Understanding novel fire regimes using plant trait-based approaches: An introduction 利用植物特性为基础的方法理解新的火灾制度：介绍。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-28 DOI: 10.1002/ajb2.70120

Kasey E. Barton, Stephanie G. Yelenik, Dylan W. Schwilk, Imma Oliveras Menor, Timothy J. Curran, Pedro Jaureguiberry, Alessandra Fidelis

引用次数: 0

Fire avoidance and long-term population decline in the endangered Florida ground lichen Cladonia perforata within a pyrogenic habitat 在一个热原栖息地内，濒危的佛罗里达地衣穿孔枝苔的防火和长期种群下降。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-28 DOI: 10.1002/ajb2.70118

Sterling A. Herron, Katherine T. Charton, Sarah J. Haller Crate, Stacy A. Smith, Scott G. Ward, Eric S. Menges, Aaron S. David

Premise

Fire is a key ecological process that shapes ecosystems globally, yet fire adaptation strategies remain unclear for many species, especially for ground lichens that are reliant on pyrogenic landscapes but are evidently fire-intolerant. In the pyrogenic Florida scrub, fire-sensitive Cladonia ground lichen species are an important component of the ground layer and influence ecosystem processes. The endangered Cladonia perforata is of special concern because fire regimes can dictate the persistence of the species. We aim to clarify (1) its subpopulation trends, (2) its post-fire recovery, and (3) the influence of microhabitat factors on these patterns.

Methods

We analyzed 14 years of detailed monitoring data from nine Cladonia perforata subpopulations on the Lake Wales Ridge that experienced eight fires. We used subpopulation area, occupancy, and fine-scale cover to estimate abundance on multiple spatial scales and analyzed the effects of burn severity, dominant ground cover, and canopy cover on C. perforata abundance over time.

Results

Abundance declined across almost all subpopulations (decreased odds ratio 0.14 for occupancy and 0.20 for cover per year). Severe fire reduced abundance, and subpopulations did not recover. Abundance was highest in litter cover, with a preference for open canopy post-fire.

Conclusions

Cladonia perforata is a fire-sensitive species with very limited growth and recolonization capacity. The detrimental fire effects here indicate a fire avoidance strategy, but litter accumulation may limit this strategy. These results highlight the delicate balance of using fire to promote the conservation of fire-sensitive species in a pyrogenic habitat.

前提：火灾是塑造全球生态系统的关键生态过程，但许多物种的火灾适应策略尚不清楚，特别是对依赖于热源景观但明显不耐火的地衣。在佛罗里达的热原灌丛中，火敏感的Cladonia地衣是地面层的重要组成部分，影响着生态系统的过程。濒危的孔雀桃特别值得关注，因为火灾制度可以决定该物种的持久性。我们的目的是澄清(1)其亚种群趋势，(2)火灾后的恢复，以及(3)微生境因素对这些格局的影响。方法：分析了威尔士湖脊9个穿孔克拉多尼亚亚群14年的详细监测数据，这些亚群经历了8次火灾。利用亚种群面积、占用率和细尺度盖度估算了多空间尺度上孔雀石的丰度，并分析了烧伤严重程度、优势地表覆盖和冠层覆盖对孔雀石丰度的影响。结果：几乎所有亚群的丰度都下降了（每年占用的优势比为0.14，覆盖的优势比为0.20）。严重的火灾减少了丰度，亚种群没有恢复。丰度在凋落物覆盖层中最高，在火灾后更倾向于开放冠层。结论：孔雀桃属火敏树种，生长和再定殖能力有限。这里的有害火灾效应表明了一种避火策略，但凋落物的积累可能限制了这种策略。这些结果强调了利用火来促进热原栖息地中火敏感物种保护的微妙平衡。

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引用次数: 0

Co-flowering with congeners does not affect buzz-pollinator specialization and pollination performance in Rhexia mariana, but does affect floral trait variance 同系物共花不影响蜂传粉者专门化和传粉表现，但影响花性状变异。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-28 DOI: 10.1002/ajb2.70119

Agnes S. Dellinger, Karolina Gwardiak, Ash Kerber, Viktoria C. Wieser, Karen D. Pérez-Arroyo

Premise

Pollinator-mediated plant-plant interactions may be negative (i.e., competition, reproductive interference) or positive (i.e., facilitation). Especially when co-flowering with close relatives (e.g., congeners), negative interactions through reproductive interference may be strong and result in floral trait divergence and increased pollination niche partitioning. However, when pollination services are limited, positive effects of pollinator sharing through floral trait similarity may outweigh the costs of reproductive interference. We therefore tested for evidence of negative or positive pollinator-mediated plant-plant interactions across a gradient of varying congeneric co-flowering contexts in the genus Rhexia (Melastomataceae).

Methods

We studied pollinator interactions, pollination performance and floral traits of Rhexia mariana across nine localities of varying cogeneric co-flowering contexts (up to seven Rhexia species co-flowering) in central Florida, USA.

Results

Regardless of co-flowering context, differential pollinator specialization was weak, with Bombus impatiens visiting all Rhexia species, removing pollen through buzz-pollination. Co-flowering context did not affect visitation rates or pollination performance, but the floral traits of R. mariana differed signficantly and were less variable in low compared to high co-flowering contexts.

Conclusions

We did not find support for either negative or positive effects of co-flowering on pollination performance in Rhexia mariana, indicating that co-flowering may instead have neutral effects. Negative effects of co-flowering with close relatives hence do not seem to be strong enough to drive specialization on distinct buzzing bee pollinators in Rhexia. Sampling across more localities, paired with experimental approaches (e.g., manipulating co-flowering density, assessing post-zygotic reproductive barriers) will be essential to clarify whether reproductive interference through co-flowering is indeed low.

前提：传粉媒介介导的植物-植物相互作用可能是消极的（即竞争、生殖干扰）或积极的（即促进）。特别是与近亲共花（如同系物）时，通过生殖干扰的负交互作用可能很强，导致花性状分化和授粉生态位分配增加。然而，当授粉服务有限时，通过花性状相似性共享传粉者的积极影响可能超过生殖干扰的代价。因此，我们测试了传粉媒介介导的植物-植物相互作用在不同同属共花环境梯度中的负或正证据。方法：在美国佛罗里达州中部9个不同共属共花环境（多达7种共花）中，研究了不同传粉媒介的相互作用、传粉表现和花性状。结果：在不同的共花环境下，不同传粉媒介的专门化程度较弱，凤仙花会拜访所有的凤仙花，通过蜂群传粉去除花粉。共花环境对访花率和传粉性能没有影响，但花性状在低花和高花环境下差异显著，变化较小。结论：我们没有发现共花对红草传粉表现的负面或正面影响，表明共花可能具有中性影响。因此，与近亲共花的负面影响似乎不足以推动不同蜂传粉媒介的专业化。在更多的地方进行采样，并结合实验方法（例如，操纵共花密度，评估合子后生殖障碍），将对澄清共花是否确实低的生殖干扰至关重要。

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引用次数: 0

The spatiotemporal origin of Polynesian blueberries (Vaccinium) 波利尼西亚蓝莓的时空起源。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-21 DOI: 10.1002/ajb2.70113

Anna L. Becker, Andrew A. Crowl, Andre S. Chanderbali, Pamela S. Soltis, Nico Cellinese, Peter W. Fritsch

Premise

We aimed to elucidate the spatiotemporal origins and biogeographic history of Polynesian blueberries within Vaccinium sect. Myrtillus, specifically those endemic to Hawaiʻi and the closely related V. cereum in southeastern Polynesia.

Methods

A HybSeq data set was constructed for Polynesian Vaccinium and added to a previously published data set for tribe Vaccinieae. Phylogenomic, ancestral area, fossil-calibrated divergence time, and phylogenetic network analyses were conducted to assess the origin and biogeographic history of the group.

Results

Hawaiʻian taxa plus a sample of Vaccinium cereum from Ua Pou Island formed a clade that was phylogenetically nested within continental Vaccinium sect. Myrtillus. The clade was inferred to have originated from temperate East Asia ca. 7.1–5.2 million years ago, dispersing to Kauaʻi either directly or via one of the subsident or now-submerged Northwestern Islands of the archipelago. Nuclear-plastid genome discordance and network analysis corroborated the previously hypothesized hybrid origin of V. cereum and suggested a possible dispersal from Hawaiʻi to coastal North America followed by introgression into the mainland species V. ovalifolium.

Conclusions

Our study suggests that an ancestral exaptation to temperate climates and an evolutionary history of the Hawaiʻian Vaccinium clade dating back at least to the origin of Kauaʻi have likely contributed to the present-day diversity of the group. Our results support a temperate East Asian origin, rare among the native plants of Hawaiʻi, and highlight the ongoing potential for both short- and long-distance dispersal in this group of island plants without a reduction or loss of dispersibility.

前提：我们旨在阐明波利尼西亚蓝莓的时空起源和生物地理历史，特别是夏威夷特有的蓝莓和波利尼西亚东南部近缘的蓝莓。方法：建立波利尼西亚痘苗的HybSeq数据集，并将其添加到先前发表的痘苗科部落数据集中。系统基因组学、祖先区域、化石校准的分化时间和系统发育网络分析评估了该群体的起源和生物地理历史。结果：夏威夷的分类群和Ua Pou岛的一株灰莲形成了一个进化分支，在系统发育上嵌套在大陆灰莲科Myrtillus中。据推测，该分支起源于约710万至520万年前的温带东亚，直接或通过群岛的一个下沉或现在被淹没的西北岛屿分散到考艾岛。核质体基因组的不一致和网络分析证实了先前假设的杂交起源，并提出可能从夏威夷扩散到北美沿海，然后渗透到大陆物种V. ovalifolium。结论：我们的研究表明，对温带气候的祖先迁移和夏威夷Vaccinium分支的进化史至少可以追溯到考艾岛的起源，这可能有助于该群体今天的多样性。我们的研究结果支持温带东亚起源，这在夏威夷本土植物中是罕见的，并强调了在不减少或失去分散性的情况下，这组岛屿植物的短期和长距离扩散的持续潜力。

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引用次数: 0

In situ ambient vibration modal analysis of saguaro cacti (Carnegiea gigantea) 仙人掌的原位环境振动模态分析。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-21 DOI: 10.1002/ajb2.70116

Jeffrey R. Moore

Premise

The structural and dynamic properties of columnar cacti are key inputs for stability analyses; however, no previous studies have been able to resolve these properties from full-scale tests in situ.

Methods

I present an approach using non-destructive ambient vibration data to measure the resonance properties (modal frequencies and mode shapes) of single-stem saguaro cacti and resolve key biomechanical properties. I tested the approach on 11 spears in the Tucson, Arizona region, United States.

Results

Saguaro fundamental frequencies ranged between 0.55 and 3.7 Hz with damping ratios of 1.5–2.1%. Additional higher-order modes were identified below 10 Hz. Fundamental frequencies scaled linearly with the ratio of stem diameter to height-squared, but deviated from analytical theory due to an observed increase in Young's modulus for taller plants. Calculated ratios between second- and first-order bending frequencies also deviated from beam theory, indicating that stiffness decreases vertically for a given stem, especially for taller spears. These deviations both likely arise from the morphology of internal wooden ribs, which provide the main flexural rigidity. Numerical modeling at one site confirmed the cantilever approximation and height-dependent stiffness, revealing an empirically derived Young's modulus that decreased exponentially from 10⁷ Pa at the top of the stem to 10⁸ Pa at its base. Twelve days of monitoring at another site showed that frequencies drift with diurnal cycles, suggesting softening of the outer tissue as temperatures warm during the day.

Conclusions

This non-destructive approach for structural assessment provides valuable data for biomechanical characterization and stability and ecological analyses.

前提：柱状仙人掌的结构和动力特性是稳定性分析的关键输入；然而，以前没有研究能够通过原位全面测试来解决这些特性。方法：我提出了一种使用非破坏性环境振动数据来测量单茎仙人掌的共振特性（模态频率和模态振型）并解决关键生物力学特性的方法。我在美国亚利桑那州图森地区的11支长矛上测试了这种方法。结果：Saguaro基频范围为0.55 ~ 3.7 Hz，阻尼比为1.5 ~ 2.1%。在10hz以下确定了其他高阶模态。基频与茎直径与高度的平方之比成线性比例，但由于观察到较高植物的杨氏模量增加而偏离了解析理论。二阶和一阶弯曲频率之间的计算比率也偏离了梁理论，这表明对于给定的杆，特别是对于较高的矛，刚度垂直下降。这些偏差都可能来自内部木肋的形态，它提供了主要的抗弯刚度。在一个地点的数值模拟证实了悬臂近似和高度相关的刚度，揭示了经验推导的杨氏模量从茎的顶部107 Pa指数下降到茎的底部108 Pa。在另一个地点进行的为期12天的监测显示，频率随昼夜周期而变化，这表明随着白天温度的升高，外部组织会软化。结论：这种非破坏性的结构评估方法为生物力学表征、稳定性和生态分析提供了有价值的数据。

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引用次数: 0

Reconstructing the evolutionary history of herbaceous crops through trait-based ecology 基于性状生态学的草本作物进化史重构

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-21 DOI: 10.1002/ajb2.70107

Alicia Gómez-Fernández

Reconstructing the evolution of crop plants is fundamental to understanding their origins, ecological adaptations, and impacts on ecosystem processes. However, our understanding of crop evolution stems largely from archaeology and genetics, with less focus on a trait-based ecological approach. Crop-specific studies have shown that phenotypic traits changed substantially during domestication and modern breeding. Yet, global comparative analyses across multiple species and traits remain scarce. Moreover, we largely ignore which plant traits distinguish wild species that were domesticated (progenitors) from those that were not, and how their ecological profiles differ. Here, I propose a conceptual model that integrates crops, their wild progenitors, and other non-domesticated herbaceous species into Grime's CSR theory and the integrated framework of plant form and function. This model provides insights into the evolutionary trajectories of domesticated plants along economics, root-microbial collaboration, and size spectra, shedding light on the ecological strategies of the wild progenitors of crops. After a comprehensive review, I emphasize that crops and their wild progenitors share similar resource-use traits, as progenitors were already highly acquisitive species. Conversely, main trait differences between domesticated and progenitor plants occur along size and collaboration axes, driven primarily by selection of large-seeded genotypes and intensive agricultural practices, respectively. I propose that crops deviate from the disturbance-adapted strategies of their wild progenitors toward more competitive ones, including links to different stages of evolution under cultivation. Finally, I outline implications for future breeding programs and the origins of agriculture, and recommend research directions to further advance our understanding of crop evolution.

重建作物的进化是理解其起源、生态适应和对生态系统过程影响的基础。然而，我们对作物进化的理解主要来自考古学和遗传学，很少关注基于性状的生态学方法。作物特异性研究表明，在驯化和现代育种过程中，表型性状发生了实质性变化。然而，跨多个物种和性状的全球比较分析仍然很少。此外，我们在很大程度上忽略了哪些植物特征区分了驯化的野生物种（祖先）和未驯化的野生物种，以及它们的生态概况有何不同。在这里，我提出了一个概念模型，将农作物及其野生祖先和其他非驯化草本物种整合到Grime的CSR理论和植物形态和功能的整合框架中。该模型提供了对驯化植物沿着经济学、根-微生物协作和大小光谱的进化轨迹的见解，揭示了作物野生祖先的生态策略。在综合综述之后，我强调作物及其野生祖先具有相似的资源利用特征，因为祖先已经是高度获取的物种。相反，驯化植物和祖先植物之间的主要性状差异发生在大小轴和协作轴上，主要是由大种子基因型的选择和集约化农业实践分别驱动的。我认为，农作物偏离了它们的野生祖先适应干扰的策略，转向了更具竞争力的策略，包括与栽培下不同进化阶段的联系。最后，我概述了对未来育种计划和农业起源的影响，并推荐了进一步推进我们对作物进化的理解的研究方向。

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引用次数: 0

Floral specialization for beetle pollination and its implications for pollen dispersal in an African orchid 非洲兰花甲虫传粉的花专门化及其对花粉传播的影响。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-20 DOI: 10.1002/ajb2.70117

Steven D. Johnson, Nina Hobbhahn, Timotheüs van der Niet, Anton Pauw

Premise

Pollination by beetles is relatively rare in orchids, and this has been attributed to the clumsy behavior of beetles being unsuitable for the precise pollen transfer mechanisms that characterize the orchid family. We investigated floral specialization for beetle pollination in the rare fire-dependent South African orchid Disa elegans and explored its implications for the efficiency and spatial pattern of pollen dispersal.

Methods

We observed flower visitors and identified their pollen loads. We studied floral traits, including spectral reflectance patterns, nectar secretion, and scent chemistry. We tracked the dispersal of color-labeled pollen.

Results

Disa elegans was found to be pollinated by large scarab beetles. Apparent floral adaptations for beetle pollination include the platform-like corymbose inflorescence of upward-facing, bowl-shaped flowers, secretion of very dilute nectar on exposed surfaces of the petals, and fruity floral scent dominated by the monoterpene alcohol R-(–)-β-linalool and benzenoid ester methyl benzoate. Beetles carry large loads of pollinaria and transfer ~13% of the pollen they remove from anthers to stigmas. We found a classic leptokurtic kernel of pollen dispersal with an average distance from donors to recipients of 6.7 m. Self-pollen made up ~30% of all pollen deposited on stigmas by beetles. These pollen dispersal patterns are similar to those obtained in plants pollinated by other insect groups, such as bees.

Conclusions

These results provide evidence of floral specialization for beetle pollination in an orchid species and show that beetles can be effective agents of pollen dispersal in orchid populations.

前提：甲虫授粉在兰花中是相对罕见的，这是由于甲虫笨拙的行为不适合兰花家族特有的精确花粉传递机制。研究了稀有的南非火依赖性兰甲虫传粉的花专门化，并探讨了其对花粉传播效率和空间格局的影响。方法：对访花者进行观察，鉴定其花粉量。我们研究了花的特征，包括光谱反射模式、花蜜分泌和气味化学。我们追踪了不同颜色花粉的传播。结果：发现秀丽隐杆线虫是由大圣甲虫授粉的。对甲虫授粉的明显的花适应包括：盆状花的平台状伞房花序，在花瓣暴露的表面分泌非常稀的花蜜，以及以单萜醇R-(-)-β-芳樟醇和苯甲酯苯甲酸甲酯为主的果香味。甲虫携带大量花粉，并将它们从花药中取出的约13%的花粉转移到柱头。我们发现一个典型的细峰花粉散布核，从施主到受主的平均距离为6.7 m。自交花粉约占甲虫在柱头上沉积花粉的30%。这些花粉传播模式与其他昆虫（如蜜蜂）授粉的植物相似。结论：这些结果为甲虫传粉的花专门化提供了证据，表明甲虫在兰花种群中是有效的花粉传播媒介。

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