Animals employ quantitative abilities to gauge crucial aspects of their environment, such as food or predator density in a given area or the number of eggs in a nest. These quantitative skills hold ecological implications and can impact an animal’s fitness. However, our comprehension of how these abilities intersect with environmental challenges remains limited. We tested for spontaneous quantity discrimination in the sleepy lizard (Tiliqua rugosa), a long-lived species known for forming life-long pair bonds in which pairs come together for the breeding season. We subjected lizards to a Y-maze experiment presenting both discrete (comparisons involving two vs. four, two vs. six, two vs. eight, four vs. six, four vs. eight, and six vs. eight pieces) and equivalent continuous combinations (single pieces differing in size) of pumpkin pieces. Our findings revealed that sleepy lizards exhibited spontaneous quantity discrimination, favoring the larger quantity in three discrete comparisons (eight vs. two, two vs. six, four vs. six) and two continuous comparisons (eight vs. two, eight vs. four). However, low accuracy may be attributable to difficulty in visual acuity exacerbated by difficulty discriminating quantities at small ratios. Furthermore, we found no evidence for a speed-accuracy trade-off in their decision-making process. Our results suggest that sleepy lizards likely employ multiple cues to estimate quantity accurately. Considering these results in the context of previous studies on various lizard species, it becomes apparent that lizards, as a group, offer a valuable model for unraveling the evolution of cognition, given their diverse ecology and sociobiology.

中文翻译：

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澳大利亚睡蜥蜴（Tiliqua rugosa）的自发数量歧视

动物利用定量能力来衡量环境的关键方面，例如给定区域的食物或捕食者密度或巢中的蛋数量。这些定量技能具有生态意义，可以影响动物的健康。然而，我们对这些能力如何与环境挑战相交叉的理解仍然有限。我们测试了瞌睡蜥蜴（Tiliqua rugosa）的自发数量辨别能力，这是一种长寿的物种，以形成终生的配对关系而闻名，在繁殖季节，配对会聚集在一起。我们对蜥蜴进行了 Y 迷宫实验，该实验呈现离散（涉及两个与四个、两个与六个、两个与八个、四个与六个、四个与八个以及六个与八个部件的比较）和等效的连续南瓜块的组合（单块大小不同）。我们的研究结果表明，昏昏欲睡的蜥蜴表现出自发的数量歧视，在三个离散比较（八对二、二对六、四对六）和两次连续比较（八对二、八对四）中倾向于较大的数量。然而，低准确度可能是由于难以区分小比率的量而加剧了视力困难。此外，我们没有发现任何证据表明他们的决策过程中存在速度与准确性之间的权衡。我们的研究结果表明，昏昏欲睡的蜥蜴可能会利用多种线索来准确估计数量。考虑到之前对各种蜥蜴物种的研究结果，很明显，蜥蜴作为一个群体，鉴于其多样化的生态学和社会生物学，为揭示认知进化提供了一个有价值的模型。