Data from: Estimating resource preferences of a native bumblebee: the effects of availability and use-availability models on preference estimatess

Identifying resource preference is considered essential for developing targeted conservation plans but, for many species, questions remain about the best way to estimate preference. Resource preferences for bees are particularly difficult to determine as the resources they collect, nectar and pollen, are challenging to estimate availability and collection. Resources are traditionally measured at the flower or inflorescence level, but these measures of availability do not correspond to the resources actually used by bees. Additionally, it is unclear as to whether common models including availability are appropriate for bees which may target resources regardless of available quantities. Here we first compare two common hypotheses of resource use – the ‘random use hypothesis’ and the ‘linear preferences hypothesis’ – using three different measures of availability (pollen, flower and inflorescence) – to determine if one measure of availability was better for understanding bee pollen use. Next, the superior model using availability was compared to a novel model of bee pollen use the ‘target use hypothesis’. This model assumes that bees target some resources regardless of how much of each resource is available (but assuming resources are present at a site), and thus models preference without availability data. Of the models including availability, the linear preference model using inflorescence availability best explained the pollen use data. This suggests that bumblebee pollen use is non-random and that cues to identify and locate resources (i.e. display size and quantity) may be more important than the quantity of the resource available (i.e. pollen availability). Additionally, in most cases the target use model explained the data equal to or better than the other models suggesting bee resource use may be better modeled without measured availability data compared to linear models. These results could be important for expanding resource use analysis of bees that are difficult to quantify availability.

确定资源偏好，是制定针对性保护计划的核心前提，但针对多数物种而言，如何最优估算其资源偏好仍存在诸多争议与空白。对于蜂类而言，其资源偏好的测定尤为困难——它们所采集的花蜜（nectar）与花粉（pollen）的可获得性及采集量均难以精准量化。传统上，资源可获得性多以花或花序（inflorescence）水平进行衡量，但这类指标与蜂类实际利用的资源并不匹配。此外，当前仍不清楚纳入可获得性项的常见模型是否适用于蜂类：蜂类或许会无视资源的可获得总量，直接靶向特定目标资源。

本研究首先对比了两种经典的资源利用假说——随机利用假说（random use hypothesis）与线性偏好假说（linear preferences hypothesis），并采用花粉（pollen）、花（flower）、花序（inflorescence）三种不同的可获得性衡量指标，以探究哪种指标更适用于解析蜂类的花粉利用行为。随后，将表现最优的可获得性模型与一种全新的蜂类花粉利用模型——靶向利用假说（target use hypothesis）开展对比。该模型假设：即便不考虑每种资源的可获得量，蜂类仍会靶向特定资源（但前提是该资源存在于调查样地中），因此可在无需实测可获得性数据的前提下对蜂类的资源偏好进行建模。

在纳入可获得性项的模型中，以花序可获得性为指标的线性偏好模型对花粉利用数据的解释效果最佳。这表明熊蜂（bumblebee）的花粉利用行为并非随机，且蜂类识别与定位资源的相关线索（如资源的展示规模与数量）或许比资源本身的可获得量（即花粉可获得性）更为关键。此外，在多数情况下，靶向利用模型对数据的解释效果与其他模型相当甚至更优，这意味着相较于传统线性模型，无需实测可获得性数据的资源利用模型或许能更准确地拟合蜂类的资源利用行为。本研究结果对于难以量化资源可获得性的蜂类资源利用分析而言，具有重要的拓展应用价值。