Biology subjects

Nuehrenberg, P.

Publications and source records attributed to Nuehrenberg, P..

3 recordsLinked to original sources

bioRxiv2020

High-resolution animal tracking with integration of environmental information in aquatic systems

Acquiring high resolution quantitative behavioural data underwater often involves installation of costly infrastructure, or capture and manipulation animals. Aquatic movement ecology can therefore be limited in scope of taxonomic and ecological coverage. Here we present a novel deep-learning based, multi-individual tracking approach, which incorporates Structure-from-Motion in order to determine the 3D location, body position and the visual environment of every recorded individual. The application is based on low-cost cameras and does not require the animals to be confined or handled in any way. Using this approach, single individuals, small heterospecific groups and schools of fish were tracked in freshwater and marine environments of varying complexity. Further, we established accuracy measures, resulting in positional tracking errors as low as 1.09 {+/-} 0.47 cm (RSME) in underwater areas up to 500 m2. This cost-effective and open-source framework allows the analysis of animal behaviour in aquatic systems at an unprecedented resolution. Implementing this versatile approach, quantitative behavioural analysis can employed in a wide range of natural contexts, vastly expanding our potential for examining non-model systems and species.

ecology↗

bioRxiv2019

Socially dominant, aggressive males are poor influencers of group-consensus in a social fish

In many species, cultures, and contexts, social dominance reflects the ability to exert influence over others, and the question of what makes an effective leader is pertinent to a range of disciplines and contexts. While dominant individuals are often assumed to be most influential, the behavioral traits that make them dominant may also make them socially aversive and thereby reduce their influence. Here we examine the influence of dominant and subordinate males on group behavior in different social contexts using the cichlid fish Astatotilapia burtoni. We find that phenotypically dominant males display behavioral traits that typify leadership across taxonomic systems - aggressive, social centrality, and movement leadership, while subordinate males are passive, socially peripheral, and have little influence over movement. However, in a more complex group-consensus task involving visual cue associations, subordinate males become the most effective agents of social change. We find that dominant males are spatially distant and have lower signal-to-noise ratios of informative behavior in the association task, potentially interfering with their ability to generate group-consensus. In contrast, subordinate males are physically close to other group members, have high signal-to-noise behaviors in the association task, and visual connectivity to other group members equal to that of dominant males. The attributes that define effective social influence are therefore highly context-specific, with socially and phenotypically dominant males being influential in routine but not complex social scenarios. These results demonstrate that behavioral traits that are typical of socially dominant individuals may actually reduce their social influence in other contexts. Significance StatementThe attributes that allow individuals to attain positions of social power and dominance are common across many vertebrate social systems - aggression, intimidation, coercion. Yet these traits are socially aversive, and can make dominant individuals poor agents of social change. In a vertebrate system (social cichlid fish) we show that dominant males are aggressive, socially central, and lead group movement. Yet dominant males are poor effectors of consensus in an more sophisticated association task compared with passive, socially-peripheral subordinate males. The most effective agents of social influence possess behavioral traits opposite of those typically found in position of social dominance, suggesting the behavioral processes that generate social dominance may simultaneously place the most ineffective leaders in positions of power.

animal behavior and cognition↗

bioRxiv2019

A low-cost, open-source framework for tracking and behavioural analysis of animals in aquatic ecosystems

Although methods for tracking animals underwater exist, they frequently involve costly infrastructure investment, or capture and manipulation of animals to affix or implant tags. These practical concerns limit the taxonomic coverage of aquatic movement ecology studies and implementation in areas where high infrastructure investment is impossible. Here we present a method based on deep-learning and structure-from-motion, with which we can accurately determine the 3D location of animals, the structure of the environment in which they are moving. Further behavioural decomposition of the body position and contour of animals subsequently allow quantifying the behavioural states of each interacting animal. This approach can be used with minimal infrastructure and without confining animals to to a fixed area, or capturing and interfering with them in any way. With this approach, we are able to track single individuals (Conger Eel, Conger oceanus), small heterospecific groups (Mullus surmuletus, Diplodus sp.), and schools of animals (Tanganyikan cichlids Lamprologus callipterus) in freshwater and marine systems, and in habitats ranging in environmental complexity. Positional information was highly accurate, with errors as low as 1.67% of body length. Tracking data was embedded in 3D environmental models that could be used to examine collective decision making, obstacle avoidance, and visual connectivity of groups. By analyzing body contour and position, we were also able to use unsupervised classification to quantify the kinematic behavioural states of each animal. The proposed framework allows us to understand animal behaviour in aquatic systems at an unprecedented resolution and a fraction of the cost of established methodologies, with minimal domain expertise at the data acquisition or analysis phase required. Implementing this method, research can be conducted in a wide range of field contexts to collect laboratory standard data, vastly expanding both the taxonomic and environmental coverage of quantitative animal movement analysis with a low-cost, open-source solution.

animal behavior and cognition↗