Isaac Planas-Sitjà

PhD student isaac2

(see personal website)

Contact :

Unité d’Ecologie Sociale (USE)

ULB CP 231

Campus de la Plaine

Bd. du Triomphe, B-1050 Bruxelles

E-mail: iplanass…

Tel: 02.650.55.28 (from abroad +32.2.650.55.28)
Fax: 02.650.59.87 (from abroad +32.2.650.59.87)


Animal Behaviour

I am interested in animal behaviour in general but more precisely in collective dynamics. The ability of animals to reach complex decisions with simple rules and often poor information about the environment is fascinating. My PhD is focused on how consistent individual behavioural differences (or ‘animal personalities’) affect the collective dynamics of a group of domiciliary cockroaches. Moreover, I study the benefits of heterogenous and homogenous groups and how this ‘personality’ can be integrated in mathematical models.

Conservation Biology

Based on my background (Biodiversity and Conservation Ecology) I would like to use the knowledge of collective systems to better understand the biology of endangered social and gregarious species and therefore help to preserve their ecological niche.

Behavioural Ecology

I study the evolutionary constraints and the adaptive value of repeatable among-individual variation in behaviour and plasticity. With the use of quantitative genetics, we are currently studing the origins of the behavioural variability in the American cockroach

Research Focus:

Recent studies allow us to understand the mechanisms linking individual and collective behaviour. Nevertheless, those studies take into account that all individuals are identical. Whilst this simplification enables a relative concordance between theoretical and experimental collective patterns, a high level of disagreement persist between theory and experience. I study the “behavioural syndromes” and “personalities” within a group of American cockroaches (Periplaneta americana) to improve our understanding of the mechanisms underlying the collective decision-making process.

The objectives of my research in the Unit of Social Ecology are (i) to quantify and determine the origins and implications of personality at the collective level and (ii) to understand the existing synergies between two decision levels – individual and collective – in the case of collective decision-making and aggregation process.


Laurent Salazar M.O., Planas-Sitjà I., Deneubourg J.L. & Sempo G., (2015). Collective resilience in a disturbed environment: stability of the activity rhythm and group personality in Periplaneta americana (BEAS)

– Planas-Sitjà I., Deneubourg J.L., Gibon C., & Sempo G., (2015). Group personality during collective decision-making: a multi-level approach (Proceedings B)

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