Cosacov Andrea, Cocucci Andrea A, Sérsic Alicia N
Laboratorio de Ecología Evolutiva y Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.
Ann Bot. 2014 Jan;113(2):251-66. doi: 10.1093/aob/mct239. Epub 2013 Nov 18.
The underlying evolutionary processes of pollinator-driven floral diversification are still poorly understood. According to the Grant-Stebbins model speciation begins with adaptive local differentiation in the response to spatial heterogeneity in pollinators. Although this crucial process links the micro- and macroevolution of floral adaptation, it has received little attention. In this study geographical phenotypic variation was investigated in Patagonian Calceolaria polyrhiza and its pollinators, two oil-collecting bee species that differ in body size and geographical distribution.
Patterns of phenotypic variation were examined together with their relationships with pollinators and abiotic factors. Six floral and seven vegetative traits were measured in 45 populations distributed across the entire species range. Climatic and edaphic parameters were determined for 25 selected sites, 2-16 bees per site of the most frequent pollinator species were captured, and a critical flower-bee mechanical fitting trait involved in effective pollination was measured. Geographical patterns of phenotypic and environmental variation were examined using uni- and multivariate analyses. Decoupled geographical variation between corolla area and floral traits related to the mechanical fit of pollinators was explored using a Mantel test.
The body length of pollinators and the floral traits related to mechanical fit were strongly correlated with each other. Geographical variation of the mechanical-fit-related traits was decoupled from variation in corolla size; the latter had a geographical pattern consistent with that of the vegetative traits and was mainly affected by climatic gradients.
The results are consistent with pollinators playing a key role in shaping floral phenotype at a geographical scale and promoting the differentiation of two floral ecotypes. The relationship between the critical floral-fit-related trait and bee length remained significant even in models that included various environmental variables and an allometric predictor (corolla area). The abiotic environment also has an important role, mainly affecting floral size. Decoupled geographical variation between floral mechanical-fit-related traits and floral size would represent a strategy to maintain plant-pollinator phenotypic matching in this environmentally heterogeneous area.
传粉者驱动的花部多样化的潜在进化过程仍未得到充分理解。根据格兰特 - 斯特宾斯模型，物种形成始于对传粉者空间异质性的适应性局部分化。尽管这一关键过程将花部适应的微观和宏观进化联系起来，但却很少受到关注。在本研究中，对巴塔哥尼亚多根荷包花及其传粉者进行了地理表型变异研究，传粉者为两种体型和地理分布不同的采油蜂。
研究了表型变异模式及其与传粉者和非生物因素的关系。在分布于整个物种范围内的45个种群中测量了6个花部和7个营养性状。测定了25个选定地点的气候和土壤参数，每个地点捕获2 - 16只最常见传粉者物种的蜜蜂，并测量了有效授粉所涉及的关键花 - 蜂机械适配性状。使用单变量和多变量分析研究表型和环境变异的地理模式。使用曼特尔检验探索花冠面积与与传粉者机械适配相关的花部性状之间的解耦地理变异。
传粉者的体长与与机械适配相关的花部性状彼此高度相关。与机械适配相关的性状的地理变异与花冠大小的变异解耦；后者具有与营养性状一致的地理模式，并且主要受气候梯度影响。
结果表明传粉者在地理尺度上塑造花部表型并促进两种花部生态型的分化中起关键作用。即使在包含各种环境变量和异速生长预测因子（花冠面积）的模型中，与花部适配相关的关键性状与蜜蜂体长之间的关系仍然显著。非生物环境也起着重要作用，主要影响花部大小。花部机械适配相关性状与花部大小之间的解耦地理变异将代表在这个环境异质区域维持植物 - 传粉者表型匹配的一种策略。
