Abstract

Processing information about quantities allows animals to make optimal decisions during many natural contexts, such as foraging, territorial defense, offspring care, mate choice, and intra-sexual competition. Compared to the wealth of information available in vertebrates, much less is known in invertebrates, even though the processing of quantities is equally relevant for both taxa. Here, we used two separate ecologically relevant tasks (brood pile preference and landmark-guided foraging) to investigate two dimensions of quantitative cognition in carpenter ants: spontaneous quantitative judgments and trained use of sequential landmarks. Individual ants spontaneously discriminated between two piles of dummy cocoons both when the choice involved smaller (1 vs. 2, 3, 4) and larger numerical contrasts (2 vs. 4, 6, 8). Ants used both chemical and visual/tactile cues and their performance was dependent on the numerical ratio. In the second task, ants preferentially searched near the trained landmark (out of five identical ones) despite alterations in its position, suggesting that they used ordinal information about its location when searching for food. In this experiment, ants showed a limit at four since their performance drastically decreased when they were trained to the 5th landmark. We showed that carpenter ants use both relative quantity and relative position to make efficient decisions. Our study contributes to the scant body of knowledge available on quantitative cognition in invertebrate species.

Significance statement

There is ample experimental evidence that non-human animals are able to process quantitative information, in particular mammals, some birds, and fish, and that this ability is useful in a variety of ecologically relevant situations. Yet, information about quantitative cognition in invertebrates is very scarce. We show that individual ants are able to use both relative quantity and relative position of items. Nurse ants spontaneously discriminated between two brood piles of different sizes and foragers were able to learn to identify a landmark associated with food on the basis of its position in a series of identical ones. These results suggest that ants might use quantitative information to make optimal choices in their natural environment although the precise mechanisms underlying this ability should be further investigated.

中文翻译：

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木蚂蚁的定量认知

摘要

处理有关数量的信息使动物可以在许多自然环境中做出最佳决策，例如觅食，领土防御，后代照料，配偶选择和性竞争。与脊椎动物中可用的大量信息相比，无脊椎动物所知的信息要少得多，即使数量的处理与两个类群同样重要。在这里，我们使用了两个单独的与生态相关的任务（育雏优先和地标引导的觅食）来研究木蚂蚁中定量认知的两个维度：自发的定量判断和顺序地标的训练使用。个别蚂蚁两堆虚设茧之间自发地判别两者的时候选择参与的情况下（1对2，3，4）和更大的数值对比（2比4，6，8）。蚂蚁同时使用化学和视觉/触觉提示，它们的性能取决于数值比。在第二项任务中，尽管位置改变，但蚂蚁还是优先搜索经过训练的地标（五个相同的地标）附近，这表明蚂蚁在寻找食物时会使用有关其位置的顺序信息。在这个实验中，蚂蚁表现出了4个极限，因为当他们训练到第5个界标时，它们的性能急剧下降。我们证明了木蚂蚁使用相对数量和相对位置来做出有效的决策。我们的研究为无脊椎动物物种的定量认知提供了很少的知识。尽管位置改变，蚂蚁还是优先搜索经过训练的地标附近（五个相同的地标），这表明蚂蚁在寻找食物时会使用有关其位置的顺序信息。在这个实验中，蚂蚁表现出了4个极限，因为当他们训练到第5个界标时，它们的性能急剧下降。我们证明了木蚂蚁使用相对数量和相对位置来做出有效的决策。我们的研究为无脊椎动物物种的定量认知提供了很少的知识。尽管位置改变，蚂蚁还是优先搜索经过训练的地标附近（五个相同的地标），这表明蚂蚁在寻找食物时会使用有关其位置的顺序信息。在这个实验中，蚂蚁表现出了4个极限，因为当他们训练到第5个界标时，它们的性能急剧下降。我们证明了木蚂蚁使用相对数量和相对位置来做出有效的决策。我们的研究为无脊椎动物物种的定量认知提供了很少的知识。我们证明了木蚂蚁使用相对数量和相对位置来做出有效的决策。我们的研究为无脊椎动物物种的定量认知提供了很少的知识。我们证明了木蚂蚁使用相对数量和相对位置来做出有效的决策。我们的研究为无脊椎动物物种的定量认知提供了很少的知识。

重要性声明

有大量的实验证据表明非人类动物能够处理定量信息，特别是哺乳动物，某些鸟类和鱼类，并且这种能力在各种与生态相关的情况下都是有用的。但是，关于无脊椎动物定量认知的信息非常匮乏。我们证明了单个蚂蚁能够使用物品的相对数量和相对位置。护士蚂蚁自发区分了两个不同大小的育雏堆，觅食者能够根据一系列相同食物的位置来学习识别与食物相关的地标。这些结果表明，蚂蚁可能会在自然环境中使用定量信息做出最佳选择，尽管应进一步研究这种能力的确切机制。