Tan Ken, Dong Shihao, Liu Xiwen, Chen Weiweng, Wang Yuchong, Oldroyd Benjamin P, Latty Tanya
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Xufu Road 88, Kunming, 650223, Yunnan Province, China.
Eastern Bee Research Institute, Yunnan Agricultural University, Kunming, 650201, China.
J Anim Ecol. 2015 Mar;84(2):509-17. doi: 10.1111/1365-2656.12288. Epub 2014 Oct 20.
Most models of animal choice behaviour assume that desirable but unavailable options, such as a high quality, but inhabited nest sites, do not influence an individual's preferences for the remaining options. However, experiments suggest that in mammals, the mere presence of such 'phantom' alternatives can alter, and even reverse, an individual's preferences for other items in a choice set. Phantom alternatives may be widespread in nature, as they occur whenever a resource is visible, but unavailable at the time of choice. They are particularly relevant for nectar-foraging animals, where previously rewarding flowers may sometimes be empty. Here, we investigate the effect of phantom alternatives on feeder preferences in the eastern honeybee, Apis cerana. First, we tested the effects of unattractive and attractive phantom alternatives by presenting individual bees with either a binary choice set containing two feeders that differed strongly in two qualities, but were equally preferred overall ('option 1' and 'option 2'), or a ternary choice set containing option 1, option 2 and one of two phantom types (unattractive and attractive). Secondly, we determined whether phantoms increase (similarity effect) or decrease (dissimilarity effect) preference for phantom-similar choices. In binary trials, bees had no significant preference for option 1 or option 2. However, after encountering an attractive phantom alternative, individual bees preferred option 2. The unattractive phantom did not influence bee preferences. Phantoms consistently changed individual bee preferences in favour of the phantom-similar choice. This means that the presence of an attractive food source, even if it is unavailable, can influence preference relationships between remaining items in the choice set. Our findings highlight the importance of considering the potential for phantom effects when studying the foraging behaviour of animals. Our results are particularly relevant for nectarivores, where empty but previously rewarding flowers are a common occurrence. Since an increase in pollinator visits can result in higher seed set, our results open up the possibility that by shifting pollinator preferences, empty flowers could have otherwise-unpredicted influences on community composition, plant-pollinator interactions and pollinator behaviour.
大多数动物选择行为模型都假定，那些虽理想但无法获取的选项，比如高质量但已有其他动物居住的巢穴，不会影响个体对其余选项的偏好。然而，实验表明，在哺乳动物中，这类“虚幻”替代物的存在本身就能改变，甚至逆转个体对选择集中其他项目的偏好。虚幻替代物在自然界可能广泛存在，因为只要一种资源可见但在选择时无法获取，它们就会出现。这对于采食花蜜的动物尤为重要，因为之前有花蜜的花朵有时可能已无花蜜。在此，我们研究虚幻替代物对东方蜜蜂（中华蜜蜂）采食器偏好的影响。首先，我们通过向单只蜜蜂呈现二元选择集（包含两个在两种特性上差异很大但总体上同等受偏好的采食器，即“选项1”和“选项2”）或三元选择集（包含选项1、选项2以及两种虚幻类型之一，即无吸引力的和有吸引力的），来测试无吸引力和有吸引力的虚幻替代物的影响。其次，我们确定虚幻替代物是增加（相似性效应）还是降低（相异性效应）对与虚幻物相似的选择的偏好。在二元试验中，蜜蜂对选项1或选项2没有显著偏好。然而，在遇到有吸引力的虚幻替代物后，单只蜜蜂更偏好选项2。无吸引力的虚幻替代物未影响蜜蜂的偏好。虚幻替代物始终改变单只蜜蜂的偏好，使其更倾向于与虚幻物相似的选择。这意味着即使有吸引力的食物源无法获取，其存在也能影响选择集中其余项目之间的偏好关系。我们的研究结果凸显了在研究动物觅食行为时考虑虚幻效应可能性的重要性。我们的结果对于食蜜动物尤为相关，因为无花蜜但之前有花蜜的花朵很常见。由于传粉者访花次数增加可导致更高的结实率，我们的结果开启了一种可能性，即通过改变传粉者偏好，无花蜜的花朵可能对群落组成、植物 - 传粉者相互作用和传粉者行为产生意想不到的影响。
