Colony entropy—Allocation of goods in ant colonies

Abstract

Allocation of goods is a key feature in defining the connection between the individual and the collective scale in any society. Both the process by which goods are to be distributed, and the resulting allocation to the members of the society may affect the success of the population as a whole. One of the most striking natural examples of a highly successful cooperative society is the ant colony which often acts as a single superorganism. In particular, each individual within the ant colony has a “communal stomach” which is used to store and share food with the other colony members by mouth to mouth feeding. Sharing food between communal stomachs allows the colony as a whole to get its food requirements and, more so, allows each individual within the colony to reach its nutritional intake target. The vast majority of colony members do not forage independently but obtain their food through secondary interactions in which food is exchanged between individuals. The global effect of this exchange is not well understood. To gain better understanding into this process we used fluorescence imaging to measure how food from a single external source is distributed and mixed within a Camponotus sanctus ant colony. Using entropic measures to quantify food-blending, we show that while collected food flows into all parts of the colony it mixes only partly. We show that mixing is controlled by the ants’ interaction rule which implies that only a fraction of the maximal potential is actually transferred. This rule leads to a robust blending process: i.e ., neither the exact food volume that is transferred, nor the interaction schedule are essential to generate the global outcome. Finally, we show how the ants’ interaction rules may optimize a trade-off between fast dissemination and efficient mixing. Our results regarding the distribution of a single food source provide a baseline for future studies on distributed regulation of multiple food sources in social insect colonies.

Ant Foragers Compensate for the Nutritional Deficiencies in the Colony

“…On its way back to the nest, it may communicate about its discovery by laying a stronger chemical trail and therefore encourage intranidal workers to visit the same food. Extranidal workers may continue foraging, depending on their ability to transfer their load to other congeners [43,44,47]. Our model suggests that the collective foraging strategies adopted in response to nutritional deficiencies originated from the trail-laying behavior of workers returning to the nest loaded with food.…”

“…Our final experiment demonstrated that, even if the collective decision depended initially on the extranidal workers' own nutritional state, this decision could be strengthened or reversed depending on the nutritional state of the recruited intranidal workers. Recently, it has been shown that heterogeneity in crop contents can be relatively high within a colony, even if the foods collected by each forager are distributed via repeated mouth-to-mouth exchange to almost every ant in the colony [47]. It follows that individuals have the potential to reach their individual intake targets by soliciting food from a range of ants in the colony [47].…”

“…Recently, it has been shown that heterogeneity in crop contents can be relatively high within a colony, even if the foods collected by each forager are distributed via repeated mouth-to-mouth exchange to almost every ant in the colony [47]. It follows that individuals have the potential to reach their individual intake targets by soliciting food from a range of ants in the colony [47].…”

Dual‐fluorescence imaging and automated trophallaxis detection for studying multi‐nutrient regulation in superorganisms

“…While it has shed light on regulatory mechanisms of a single carbohydrate-based food source (Greenwald, Baltiansky, and Feinerman, 2018), it is not suitable for studying the simultaneous flows of several food types. To study dynamics of mixing and differential dissemination of several food sources with data from the previous method, assumptions had to be made regarding the homogenization of food in the crop (Greenwald, Eckmann, and Feinerman, 2019). We introduced the ability to directly track two fluorescent dyes.…”

“…The chosen fluorophores were Rhodamine B (λ ex 533 nm, λ em 627 nm) (used in Greenwald, Segre, and 143 Feinerman, 2015;Greenwald, Baltiansky, and Feinerman, 2018;Greenwald, Eckmann, and Feinerman, 2019),…”