Nicolaus group – Behavioural Biology

Individual animals of the same population often differ consistently in (suites of) behaviours across time and context (so-called ‘personality’) and their degree of behavioural plasticity. These differences are intriguing because high behavioural flexibility should be favourable and yet it is far from being the norm. My group seeks to uncover why this is the case, how is such variation maintained through time and what are the eco-evolutionary consequences of such variation. With this knowledge, we ultimately aim to predict adaptive capacities of wildlife and help design the best possible conservation measures.

We aim to unravel the mechanisms of adaptation in animals by studying how the proximate mechanisms generate behavioural variation and how these processes affect the evolved solutions (e.g. adaptive dispersal) to fast environmental changes (e.g. habitat fragmentation) and impact animal population dynamics and genetics. To reach that aim, we study behavioural variation from a variety of angles and at three levels of organization – between populations, between individuals and within individuals – by combining field studies and experiments in semi-natural conditions and laboratory settings on fish and birds.

Current projects

Animal personality as a driver of reproductive isolation?  (A. Schlatmann)

Personality variation influences how individuals distribute and interact with each other’s. As a consequence such phenomena could promote personality-based mating and, potentially, be a first step towards reproductive isolation and species divergence.

This PhD project investigates whether and how personality variation can contribute to personality-based assortative mating in animal populations. This is addressed by experimental studies on three-spined sticklebacks (Gasterosteus aculeatus) where populations of ‘migrants’ were isolated in freshwater habitats becoming ‘residents’, following habitat fragmentation ~50 years ago. These populations of residents and migrants differ genetically in movement and social behaviours. Experiments will test mechanisms potentially driving mating by personality, such as the temporal and spatial segregation of personality types, active mate choice for personality, and behavioural plasticity. Through these investigations, a comprehensive understanding of the intricate relationship between personality variation and its ecological and evolutionary consequences can be achieved. In light of future conservation efforts to remove anthropogenic barriers, these investigations will also provide insight into the eco-evolutionary impact of bringing both ecotypes back into secondary contact.

Eco-Evo-Devo of social personalities (J. Gismann, NWO-ALW)

This PhD project aims at understanding the emergence of social personalities, using an integrative approach which considers the interplay of ecology, evolution, and development.

As controlled field experiments in aquatic environments are difficult and behaviour under lab conditions often lacks ecological validity, we developed a semi-natural experimental mesocosm system where large groups of sticklebacks could be followed individually over extended periods of time. In a number of experiments, we investigated how social and ecological conditions can shape behaviour over different time scales and how personality differences in turn can affect ecological processes. We showed that a brief history of isolation (~60 years) was sufficient to induce divergence in movement behaviour between two stickleback populations, and that individuals’ behaviour can be affected by the composition of their social group, but to a lesser degree than often concluded from the lab. We also investigated the consequences of personality variation for dispersal and found that certain personality types may facilitate movement and establishment in novel environments. Furthermore, we found that social environmental conditions experienced early in life can affect social associations later in life.  

Conservation implications of animal personality (Ruim Baan Voor Vissen 2)

Habitat fragmentation resulting from the construction of artificial barriers such as pumping stations is one of the major factors responsible for freshwater biodiversity decline. In this project, we investigate the effectiveness of fishway as mitigation measure against habitat fragmentation for fish populations. By conducting field experiments in combination with remote tracking in the wild, we investigate whether fishway passage success and survival rates near fishway are dependent on stickleback phenotype (personality, size, and timing). This work is done in collaboration with researchers from Van Hall Larenstein Applied Sciences University and Hunze en Aa’s local water authority.