Individual differences drive movement and foraging dynamics in shoaling fish (2016 – Present)
Supervisors: Prof Iain Couzin
In the field of organismal biology, consistent inter-individual differences in behaviour has experienced surging interest in the past decade. Accumulating evidence across a variety of species suggests that some individuals are consistently more explorative, more aggressive, or ‘bolder’ than other individuals and that these consistent differences in behaviour are often heritable and related to the individual’s fitness (Dingemanse & Reale, 2005; Smith & Blumstein, 2008). Therefore, studying such differences, their causes and evolutionary implications is essential to further our understanding of the behaviour. In this project, we use data from three-spined sticklebacks (Gasterosteus aculeatus) coupled with an agent based model to show that patterns previously thought to be a result of individual differences in sociability can result purely from individual differences in swim speeds. Further, by exposing individuals to free-schooling and foraging contexts, we show that individual differences in swim speed and goal-orientedness have consequences in terms of their spatial positioning within the group and foraging success.
Collective sensing: How animal groups scale noisy gradients (2015 – 2016)
Supervisors: Prof Iain Couzin
Individuals have sensory limitations. By living in groups, they function as an array of sensors collectively sensing the environment. Each individual is behaviourally coupled with local neighbours allowing waves of information to propagate across the group. Acquiring such indirect information allows individuals to respond to information that might otherwise be outside their reach, thus amplifying their effective sensory range. For example, foraging bats eavesdrop on echolocating calls from group mates to locate prey (Cvikel et al., 2015), fish in shoals perceive predator attacks occurring far away in the shoal (Handegard et al., 2012) and fish schools detect favourable regions in environment by emergent gradient tracking (Berdahl et al., 2013).
In this context, animal groups can be view as an array of sensors; information-processing entities with a collective awareness of their environment (Couzin, 2007). In this project, I examined how schools collectively filter noise and scale the global peaks (of darkness) in their environment. Results indicate a density dependence. Schools are attributed the ability to filter noise in light gradients by modifying inter-individual spacing such that they span a region in space larger than the noise frequency but smaller than the length scale of the signal itself.
Nest inheritance and the role of direct fitness on the evolution of eusociality (2014 – Present)
Supervisors: Prof Ido Pen; Andrés Quiñones
Cooperation by animals with non-relatives poses a challenge to kin selection theory unless direct fitness benefits are somehow obtained from the cooperative act. Several species of the Polistinae subfamily of wasps have helpers that are completely unrelated to the dominant female in the nest. Empirical studies indicate that these associations could be a result of nest inheritance by the subordinates, a very probable scenario in the species (Queller et al., 2000). Further evidence suggests that subordinates in these cofoundress associations produce more direct offspring than lone foundresses mostly post nest inheritance, but sometimes even as subordinates (Leadbeater et al., 2011) .
This model examines the role of direct fitness in the evolution of such semisocial systems. Benefits of association are classified as survival and reproductive benefits and the effect of each on subordination is examined independent of the other. Results suggest that relatedness between the dominant and the subordinate in a nest is not necessary for such complex social systems to evolve. We also find evidence for increasing complexity in such systems in the form of helping tendency in brood 1 workers (eusociality) facilitating cofoundress associations (semisociality).
Quantitative genetics of correlation between exploratory behaviour and body condition in field crickets, Gryllus bimaculatus (2014)
Supervisors: Prof Niels Dingemanse; Francesca Santostefano
The aim of this project was to investigate the consequences of the associations between state and exploratory behaviour in field crickets, Gryllus bimaculatus on maintenance of consistent between individual differences in behaviour. Wild animal models were used in order to partition the total phenotypic variance into between and within individual components. Further pedigree information was used to partition between individual variance into additive genetic in order to determine trait heritabilities and identify fraction of trait-state correlation governed by additive genetic effects.
Specifically, the aims of the project were:
1. Measure repeatability of exploratory behaviour and state measure, weight
2. Use trait correlations to identify a common underlying behavioural phenotype – exploration
3. Estimate heritabilities and genetic correlations of the traits.
Results reveal significant phenotypic negative correlation between exploratory behaviour and state of the individual at both between and within individual levels. Including a pedigree further showed that a significant portion of the between individual correlation is due to additive genetic effects, with interesting evolutionary implications.