Naked Mole-Rat Social Phenotypes Vary in Investigative and Aggressive Behavior in a Laboratory Partner Preference Paradigm

Abstract

Here we employed the partner preference test (PPT) to examine how naked mole-rat non-breeding individuals of different behavioral phenotypes make social decisions. Naked mole-rats from six colonies were classified into three behavioral phenotypes (soldiers, dispersers, and workers) using a battery of behavioral tests. They then participated in a 3 h long PPT, where they could freely interact with a tethered familiar or tethered unfamiliar conspecific. By comparing the three behavioral phenotypes, we tested the hypothesis that the PPT can be used to interrogate social decision-making in this species, revealing individual differences in behavior that are consistent with discrete social phenotypes. We also tested whether a shorter, 10 min version of the paradigm is sufficient to capture group differences in behavior. Overall, soldiers had higher aggression scores toward unfamiliar conspecifics than both workers and dispersers at the 10 min and 3 h comparison times. At the 10 min comparison time, workers showed a stronger preference for the familiar animal’s chamber, as well as for investigating the familiar conspecific, compared to both dispersers and soldiers. At the 3 h time point, no phenotype differences were seen with chamber or investigation preference scores. Overall, all phenotypes spent more time in chambers with another animal vs. being alone. Use of the PPT in a comparative context has demonstrated that the test identifies species and group differences in affiliative and aggressive behavior toward familiar and unfamiliar animals, revealing individual differences in social decision-making and, importantly, capturing aspects of species-specific social organization seen in nature.

The dissection of a despotic society: exploration, dominance and hormonal traits

“…Naked mole-rat subordinates can be classified into three behavioural phenotypes: soldiers, workers and disperser morphs which are linked to differences in behaviour [32,33]. Soldiers are linked to aggressive behaviour towards foreign conspecifics, whereas workers are non-aggressive and non-explorative individuals [33,34], while dispersers are linked to exploration behaviour owing to them persistently exploring burrow openings to disperse [35]. Exploration is a behavioural trait that has been linked to social dominance in many group-living species [36].…”

“…Only 1% of non-reproductive subordinate individuals ever attain reproductive status in the naked mole-rat and less than 15% in the Damaraland mole-rat, as they are reproductively suppressed by the dominant breeding individuals while in a colony [10,31]. Naked mole-rat subordinates can be classified into three behavioural phenotypes: soldiers, workers and disperser morphs which are linked to differences in behaviour [32,33]. Soldiers are linked to aggressive behaviour towards foreign conspecifics, whereas workers are non-aggressive and non-explorative individuals [33,34], while dispersers are linked to exploration behaviour owing to them persistently exploring burrow openings to disperse [35].…”

Behavioral fingerprinting of the naked mole-rat uncovers signatures of eusociality and social touch

“…Their behavior is also reflective of their dominance hierarchy, with the top-ranked queen dominating subordinates through shoving and biting (Clarke & Faulkes, 2001). Whether naked mole-rats display a true caste-like organization of behavior or if behaviors are more fluid across colony members is still being actively investigated (Siegmann et al, 2021; Toor et al, 2022). Moreover, how their complex repertoire of behavior interacts with their dominance hierarchy remains unresolved.…”