Nathan Pooja, Shahid Arshyaan, Datta Anoushka, Gowda Vinita, Frederickson Megan E
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
Department of Wildlife Science, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India.
Oecologia. 2025 Jul 11;207(8):130. doi: 10.1007/s00442-025-05772-7.
The Biotic Interactions Hypothesis (BIH) predicts that species interactions will intensify from the poles to the tropics. We studied the ant-plant defensive interaction mediated by extrafloral nectaries (EFNs) in the castor bean plant, Ricinus communis, across a ~ 21° latitudinal gradient in its naturalized range in India. Among our study sites, we found that the ant-EFN mutualism in castor bean gets stronger from sub-tropical to tropical latitudes. Investment in mutualism by plants and visitation by ants increased from higher to lower latitudes. Further, latitude significantly explained ant community composition. However, contrary to the predictions of the BIH, standing herbivory increased with latitude, perhaps because plants invest less in biotic defence at higher latitudes. To our knowledge, our study is the first to test for the patterns predicted by the BIH for an ant-plant interaction in the Paleotropics. Results from our study can also help inform sustainable pest control practices for R. communis since India is the world's largest producer of castor oil.
生物相互作用假说（BIH）预测，物种间的相互作用将从极地向热带地区增强。我们研究了蓖麻（Ricinus communis）上由花外蜜腺（EFNs）介导的蚂蚁与植物的防御性相互作用，该研究跨越了印度归化范围内约21°的纬度梯度。在我们的研究地点中，我们发现蓖麻中蚂蚁与花外蜜腺的互利共生关系从亚热带到热带纬度逐渐增强。植物对互利共生的投入以及蚂蚁的访花频率从高纬度到低纬度都有所增加。此外，纬度显著解释了蚂蚁群落的组成。然而，与生物相互作用假说的预测相反，现存食草动物的数量随纬度增加，这可能是因为植物在高纬度地区对生物防御的投入较少。据我们所知，我们的研究是首次在古热带地区针对生物相互作用假说所预测的蚂蚁与植物相互作用模式进行检验。由于印度是世界上最大的蓖麻油生产国，我们的研究结果也有助于为蓖麻的可持续害虫防治实践提供参考。
