We conduct evolutionary behavioural ecology research, asking questions about the adaptive evolution of behavioural strategies, and their genetic architectures, within an ecological context. Our research is motivated by behavioural ecology, life-history, and quantitative genetics theory, and seeks to test predictions and assumptions of adaptive theory using observational and experimental approaches in the laboratory and the wild.
We monitor 12 nest box populations of a passerine bird model (the great tit) south of Munich since 2010, providing unique longitudinal data of breeders and their offspring with respect to various key life-history and behavioural traits. We can thus uniquely study the action of selection and why it may favour a modular trait structure, such as represented by the integration between life-history and behavioural strategies (‘pace-of-life syndromes’) in the wild.
We primarily focus on behaviours mediating the trade-off between current and future reproduction, such as aggressiveness and exploratory tendency, and use large-scale population-level environmental manipulations (predation risk, resource availability) to study how the interaction between ecological and population-level processes shape the adaptive evolution of trait integration in the wild. We use genetic pedigrees to estimate parameters key in testing evolutionary theory in the wild, while laboratory studies of pedigreed insect models (field crickets) further allow us to study how the interaction between genes and environment (e.g. diet, competitive regimes) shaped the genetic architecture of life-history behaviour.
Our group is further at the forefront of the development of statistical tools to quantify multi-level and multi-variate variation. For example, we have developed with a team of international collaborators an educational software package entitled SQUID (Statistical Quantification of Individual Differences) that enables self-teaching and research into mixed-effects modelling analyses and optimal sampling designs.
Evolutionary ecology of behavioural stability in natural bird populations
Funded by the German Science Foundation, PhD-students Alexander Hutfluss and Alexia Mouchet
Recent studies have provided compelling evidence for the existence of individuality in average behaviour (animal personality), responsiveness to environmental change (individual plasticity) and within-individual variability (behavioural stability). While research has thoroughly investigated the evolutionary ecological causes and consequences of personality and individual plasticity, this is not so for individuality in behavioural stability. Theory postulates that stable phenotypes are costly to produce (thus under sexual selection), or affect predation risk (thus under natural selection). The overarching objective of this DFG-project is to study the proximate and ultimate mechanisms shaping (the integration between) individual variation in personality, behavioural plasticity, and behavioural stability in the wild. Our specific objective is to study how the expression of within- and among-individual variance in each of these three types of behavioural characteristics, as well as their associations with key fitness components, vary with competitive regimes. We are focusing on stability in bird song, using pedigreed wild populations of great tits as a perfect model system. We are executing large-scale manipulations of competitive regimes (population density in particular) to test its role in causing heterogeneous selection acting on behavioural stability in bird song and its hypothesized correlates (key behaviours: aggressiveness and exploratory tendency). Our setup (12 nest box plots with 50 boxes each) is ideal for performing large-scale manipulations, with which we have ample experience.
We study proximate and ultimate perspectives in conjunction. We are identifying the sources of variation in behavioural stability, and determine (i) whether stability in bird song varies plastically within individuals as a function of the perceived amount of competition for resources, and (ii) whether stability in bird song shows long-term repeatability and heritability, and whether it is correlated with other key behaviours. We also focus on how selection acts on this variation, and determine (iii) the direct and indirect pathways by which selection acts on behavioural stability (e.g., via within- or extra-pair paternity, or survival), (iv) whether selection on behavioural stability fluctuates spatiotemporally (e.g., as a function of food availability and breeding density), and (v) whether fluctuating selection on correlated traits helps maintain individual variation in behavioural stability. We thereby forcefully combine proximate and ultimate viewpoints in studies of the adaptive integration of personality, individual plasticity, and behavioural stability in wild populations.
How social environments affect the selection on animal behavioural types
Funded by the Alexander von Humboldt Foundation and the German Science Foundation, Postdoc Petri T. Niemelä, Advisor: N.J. Dingemanse
The social environment, i.e. interactions between conspecifics, represents one of the most dynamic environmental forces that individuals face, because the individual’s own behaviour as well as conspecifics’ behaviours jointly defines the frequency and intensity of the interactions. Overall fitness of an individual is expected to depend not only on its own behavioural type, but also on the interaction between its own behavioural type and the composition of behavioural types in the population (i.e. its social environment). Differences between behavioural types in time budget conflicts (i.e. activity in one context is adaptive while in other context it is maladaptive) are suggested as one of the main mechanisms mitigating fitness differences between behavioural types in nature and may depend on the social environment. However, despite its role in competition, co-operation and mating, the ecological and evolutionary implications of the social environment have largely been neglected in animal personality studies. In this project, I study 1) whether behavioural plasticity is a function of behavioural type and the social environment and if 2) differences in life-time reproduction success depend on the interaction between behavioural type and social environment. As a model species, I use native field cricket species, Gryllus campestris.
Evolution of animal personalities
Funded by the Max Planck Society, PhD Student Maria Moiron, Advisor: N.J Dingemanse
From an adaptive perspective, the existence of animal personalities is still a mystery because a more flexible structure of behavior would provide a selective advantage. My project aims to understand why individuals within single populations often differ consistently in their behavioral tendencies across time and contexts. For that purpose, I will investigate the role of feedback loops in explaining how different personality types can stably coexist and persist.
Integrating pre-and post-mating episodes of sexual selection in the study of sexual trait evolution.
Funded by Biona – Junior scientist award of the Faculty of Biology (LMU) to Cristina Tuni
Reproductive success in males is determined by both, their ability to gain mating partners by displaying attractive sexual traits or fighting competitors (pre-mating sexual selection) and to fertilize female’s eggs by winning competitive interactions against sperm of rival males (post-mating sexual selection). Males that experience higher mating success do not necessarily achieve higher fertilization success due to trade-offs in life-history resource allocation, where energy allocated to mate acquisition will limit any further post-mating investment. Negative correlation between pre- and post-mating traits may indicate that the two forms of selection counteract one another, with profound implications in dictating the rate and direction of evolutionary change. This study investigates phenotypic and genetic correlations between key morphological and behavioural pre- and post-mating sexual traits in the field cricket Gryllus bimaculatus with the aim of revealing evolutionary trade-offs between mating and sperm competition success.
The evolution of deceptive behaviour in nuptial gift-giving spiders
Funded by GSST - Graduate school of science and technology (Aarhus University, Denmark). PHD Student Paolo Giovanni Ghislandi; Advisors: Cristina Tuni and Prof. Trine Bilde (Aarhus University).
The main goal of this project is to understand how sexual selection drives population divergence in polymorphisms of male sexual traits. Specifically, it will examine how sexual selection shapes the evolution of stable polymorphisms in male alternative reproductive traits in male spiders. In order to increase their mating success males of the species Pisaura mirabilis donate nuptial food gifts to females that consume them during copulation. Gifts vary in their quality consisting of genuine nutritional (prey) gifts or deceptive inedible items eliciting female mate acceptance without conferring any food reward. There is evidence that these traits occur in different frequencies across populations, suggesting differential selective forces among populations. After understanding whether deceptive is fixed or variable and context dependent we will determine whether stable polymorphisms vary consistently among populations, quantifying the frequency of polymorphisms in male traits in multiple spider populations and exploring the ecological factors that lead to male deception.