Tandem Recruitment Research Articles

Functional and mechanistic diversity in ant tandem communication

Communication is fundamental to the organization of animal societies, often resulting in the convergent evolution of similar social behavior across lineages. However, this similarity may conceal underlying functional and mechanistic differences. Here we combined network and information-theoretic analysis to quantify how tandem recruitment is distinguishable between two ant genera, Temnothorax and Diacamma. We show that Temnothorax uses tandem running to recruit additional recruiters, while Diacamma uses it principally to move the passive majority of their colony, a task that Temnothorax accomplishes with a different behavior, social carrying. Accordingly, the network structure of Diacamma tandems was dissimilar to that of Temnothorax, instead resembling the social-carrying networks in Temnothorax. Furthermore, our information-theoretical analysis on movement trajectories revealed that Diacamma tandem runs lack bidirectional information transfer, the signature of route learning in Temnothorax. By quantifying the diversity of similar communication systems, this study increases the resolution of our understanding of animal societies.

Recruitment of scarce competences to rural regions: Policy perspectives

This paper studies the perceived difficulty of recruiting scarce competencies to rural regions. Furthermore, the role of policy in facilitating and enhancing recruitment to and better skills matching in rural regions is discussed. Based on a survey targeted to the business sections of Swedish municipalities, the results show that recruitment is perceived to be difficult in both rural and nonrural regions and that the difficulty of recruiting for the right skills results in a lack of skills matching and constitutes an obstacle to growth. Rural regions located close to urban areas can to some extent mitigate these recruitment problems, and their locations pose less of a barrier in recruitment processes compared to those of remotely located rural regions.Which policies can help remedy recruitment problems faced in rural regions? In both rural and nonrural regions, incentives for writing off student debt and relocation support for accompanying persons and tandem recruitment are perceived to be the most promising policies. Rural regions are more receptive to the implementation of such policies. Finally, the need for flexibility and policies that can be adapted to the regional demand for labour are stressed.

Recruitment of Dual-Career Academic Medicine Couples.

Today it is not uncommon to discover that a candidate for a faculty position has a partner or spouse who is also an academician, adding complexity to the recruitment process. Here, the authors address two practical obstacles to the recruitment of faculty who have an academic partner: dual recruitment and conflict of interest. The authors have found that tandem recruitment works best when suitable positions for both spouses are first identified so that recruitment can proceed synchronously. This approach decreases misperceptions of favoritism toward either's candidacy. Managing conflict of interest, generated by the appointment of one spouse in a supervisory position over the other, requires a proactive, transparent, well-designed plan. After canvassing human resource policies and conducting interviews with national academic leaders, the authors have developed an administrative structure that places "key" decisions (hiring and retention; promotion and tenure; salary, bonuses, and benefits; performance evaluations; and disciplinary matters) regarding the supervised spouse in the jurisdiction of an alternative administrator or committee. The authors also offer suggestions both for mitigating misperceptions of bias in day-to-day decisions and for the support and mentoring of the supervised partner or spouse.

Tandem Recruitment and Foraging in the Ponerine Ant Pachycondyla harpax (Fabricius).

Tandem running is a common recruitment strategy in ant species with small colony sizes. During a tandem run, an informed leader guides a usually naïve nestmate to a food source or a nest site. Some species perform tandem runs only during house hunting, suggesting that tandem running does not always improve foraging success in species known to use tandem running as a recruitment strategy, but more natural history information on tandem running under natural conditions is needed to better understand the adaptive significance of tandem recruitment in foraging. Studying wild colonies in Brazil, we for the first time describe tandem running in the ponerine ant Pachycondyla harpax (Fabricius). We asked if foragers perform tandem runs to carbohydrate- (honey) and protein-rich (cheese) food items. Furthermore, we tested whether the speed and success rate of tandem runs depend on the foraging distance. Foragers performed tandem runs to both carbohydrate food sources and protein-rich food items that exceed a certain size. The probability to perform a tandem run and the travelling speed increase with increasing foraging distances, which could help colonies monopolize more distant food sources in a competitive environment. Guiding a recruit to a food source is costly for leaders as ants are ~66% faster when travelling alone. If tandem runs break up (~23% of all tandem runs), followers do not usually discover the food source on their own but return to the nest. Our results show that tandem running to food sources is common in P. harpax, but that foragers modify their behaviour according to the type of food and its distance from the nest. Competition with other ants was intense and we discuss how tandem running in P. harpax might help colonies to build-up a critical number of ants at large food items that can then defend the food source against competitors.

FIRST-ORDER TRANSITION IN A SPIN MODEL FOR SELF-ORGANIZATION

The paper examines the emergence of self-organization in a population where tandem recruitment is combined with individual memory. The time evolution is modeled as a two-dimensional spin system with local interaction along the time axis and a mean-field interaction along the other axis. We generalize a previous result obtained with this model from the case of two sources to the multisource situation and show a twofold connection with the Potts model. First, when individual memory exceeds a critical value, a phase transition sets in, which is second order for two sources but first order beyond, similarly to the mean-field theory of the Potts model. In addition, the self-organization problem considered here relies on a special case of the one-dimensional nearest-neighbor Potts model with external field, which is shown to be explicitly solvable.

Social insects with memory

The paper presents a mathematical model to investigate the collective behaviour of an ant colony when memory of the ants interferes with the usual interaction between individuals. The approach is developed in the framework of a simple situation consisting in tandem recruitment in a population of conservative ants, but it is susceptible to be applied also to a wider range of problems. The principle of the method is inspired by the work of Leuthausser and Tarazona who developed the correspondence between a model for macromolecular time evolution and the equilibrium statistical mechanics of a higher-dimensional Ising system.

Field study on the foraging characteristics of a ponerine ant,Hagensia havilandi Forel

A field study of the foraging strategy used by the ponerine ant,Hagensia havilandi is reported. They have permanent nests in the leaf litter of coastal forests.H. havilandi is a diurnal forager and collects a variety of live and dead arthropods. These predatory ants exhibit individual foraging with no cooperation in the search for or retrieval of food items. Three colonies were observed and showed similar temporal and spatial foraging patterns. The paths of individual ants were followed and the results showed that the foragers exhibit area fidelity, and return to the nest via a direct route on finding on prey item. Several foragers did not return to the nest at dusk but returned the following morning. Occasionally a limited amount of tandem recruitment was displayed.

Tandem Recruitment and Trail Laying in the Ponerine Ant Diacamma rugosum: Signal Analysis1

AbstractDuring nest emigration, Diacamma rugosum scouts recruit female nestmates to the new nest site by tandem running. ♂♂, brood and prey objects are carried.The tandem leaders stimulate their nestmates to follow them by pushing or, more rarely, pulling them with the mandibles.The signals releasing the following behaviour are mainly chemical. Only 15–30% of motivated followers react positively to an odourless paper or wax dummy. The ♀♀ follow cut‐off thoraces, legs and gasters plugged at the end or without hind gut and sting apparatus, just as well as a leading ant. The ants even follow a dummy consisting of body parts if they are not in direct mechanical contact with it. The leading effect of the body surface is not reduced by intensive cleaning with water or by extraction in solvents of different polarity. Only maceration in potash lye eliminates the leading effectiveness of the cuticula. None of the secretions of the tested abdominal glands release following behavior. Only the hind gut fluid possesses leading signal qualities. No distribution of faeces over the bodies of the leading ants can be observed before or during tandem running. The faecal pheromone responsible for this leading effect does not seep into the superficial layer of a leader dummy made from bee wax but it can be washed off with water. These results show that the actual signal releasing tandem following is an unspecific odour substance of the cuticula surface. The presence of the hind gut fluid is not necessary for the tandem following response. It may be an additional signal. During nest emigration the hind gut fluid is scattered patchily in the form of small droplets by the nest finders on their way to the new nest. No increased deposition of faecal droplets could be observed on the way to repeatedly visited rich food sources.The hind gut fluid serves as a long lasting trail substance and has an exclusively orienting effect. The secretions of the other abdominal glands are not trail pheromones. The nest entrance is marked colony‐specifically.