Regulation of harvester ant foraging as a closed-loop excitable system
Regulation of harvester ant foraging as a closed-loop excitable system
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收割蚁觅食作为闭环兴奋系统的调节
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Naomi Ehrich Leonard
中科院分区：
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作者：
Renato Pagliara;D. Gordon;Naomi Ehrich Leonard
蚁群根据变化的环境调节活动，而不使用集中控制。收获蚁群在沙漠中觅食种子，它们对觅食的调节管理着消耗和获取水分之间的权衡。觅食蚁在室外干燥的空气中会失去水分，但蚁群通过代谢它们所吃的种子中的脂肪来获取水分。先前的研究表明，外出觅食的蚂蚁离开巢穴的速度取决于它最近与携带种子的觅食蚂蚁进行短暂的触角接触的经历。我们研究了这个过程是如何产生的觅食率是稳健的不确定性和响应温度和湿度在几分钟到一小时的时间尺度。为了探索可能的机制，我们开发了一个具有少量参数的低维分析模型，以捕获观察到的觅食行为。该模型使用兴奋性动力学来表示巢内相互作用的响应，并使用随机延迟分布来表示巢外觅食时间。我们展示了外出觅食者返回巢穴的反馈如何将进出觅食率稳定到一个由可用觅食者的“波动性”决定的共同值。该模型显示出一个临界波动率，高于该波动率的是持续恒定的觅食，低于该波动率的是停止觅食。为了解释蚁群的觅食率如何适应温度和湿度，我们提出了一种机制，该机制依赖于觅食者在离开巢穴并暴露于环境后改变其波动性。我们的研究强调了反馈在觅食活动调节中的重要性，并指出波动性的调节是解释不同条件下觅食活动差异的关键。我们的结果提供了推广到其他环境和系统的机会，具有兴奋性和跨多个时间尺度的反馈。作者总结：我们研究了沙漠收获蚁群体在环境条件下调节觅食活动的集体行为。我们建立了一个连接三个过程的分析模型：1)返回巢穴的觅食者与在巢内等待的可用觅食者之间的相互作用，2)这些相互作用对可用觅食者离开巢穴觅食的可能性的影响，以及3)觅食者在找到种子后返回巢穴。我们提出了一种机制，在这种机制中，可用的觅食者在第一次暴露于环境后改变他们对相互作用的反应。我们展示了这如何导致群体觅食率随着时间尺度从几分钟到几小时的环境条件而调整。我们的模型可能对研究其他类型的具有兴奋性动力学的系统的弹性有用。
Ant colonies regulate activity in response to changing conditions without using centralized control. Harvester ant colonies forage in the desert for seeds, and their regulation of foraging manages a tradeoff between spending and obtaining water. Foragers lose water while outside in the dry air, but the colony obtains water by metabolizing the fats in the seeds they eat. Previous work shows that the rate at which an outgoing forager leaves the nest depends on its recent experience of brief antennal contact with returning foragers that carry a seed. We examine how this process can yield foraging rates that are robust to uncertainty and responsive to temperature and humidity across minutes to hour-long timescales. To explore possible mechanisms, we develop a low-dimensional analytical model with a small number of parameters that captures observed foraging behavior. The model uses excitability dynamics to represent response to interactions inside the nest and a random delay distribution to represent foraging time outside the nest. We show how feedback of outgoing foragers returning to the nest stabilizes the incoming and outgoing foraging rates to a common value determined by the “volatility” of available foragers. The model exhibits a critical volatility above which there is sustained foraging at a constant rate and below which there is cessation of foraging. To explain how the foraging rates of colonies adjust to temperature and humidity, we propose a mechanism that relies on foragers modifying their volatility after they leave the nest and get exposed to the environment. Our study highlights the importance of feedback in the regulation of foraging activity and points to modulation of volatility as a key to explaining differences in foraging activity in response to conditions and across colonies. Our results present opportunities for generalization to other contexts and systems with excitability and feedback across multiple timescales. Author Summary We investigate the collective behavior that allows colonies of desert harvester ants to regulate foraging activity in response to environmental conditions. We develop an analytical model connecting three processes: 1) the interactions between foragers returning to the nest and available foragers waiting inside the nest, 2) the effect of these interactions on the likelihood of available foragers to leave the nest to forage, and 3) the return of foragers to the nest after finding seeds. We propose a mechanism in which available foragers modify their response to interactions after their first exposure to the environment. We show how this leads to colony foraging rates that adjust to environmental conditions over time scales from minutes to hours. Our model may prove useful for studying resilience in other classes of systems with excitatory dynamics.