Social interactions: intra- and inter-specific competition between blue and great tits

Gaona Gordillo, Irene (2024): Social interactions: intra- and inter-specific competition between blue and great tits. Dissertation, LMU München: Fakultät für Biologie

Abstract

Among-individual differences in behaviour are ubiquitous, yet only over the past two decades has research focused on understanding how and why among-individual differences are generated and maintained. Conceptual models from an adaptive perspective predict that among-individual differences in internal and external state lead to individual differences in behaviour, and correlations between behaviour and other phenotypic traits. Recent conceptual models imply that fluctuations in population density could promote the maintenance of variation in life-history strategies, behaviour (“animal personality”), and other correlated traits. This thesis focused on testing three predictions stemming from the theory explaining animal personality variation as an adaptation to variation in competitive regimes. First, I tested whether patterns of integration of morphological, physiological, and behavioural traits predicted by eco-evolutionary theory were, as expected, generally supported within two bird species (blue tits Cyanistes caeruleus vs. great tits Parus major), or whether these patterns differed between study populations (Forstenrieder Park vs. Starnberg), and/or between sexes (males vs. females). I further experimentally manipulated the availability of nest boxes suited for blue and great tit breeders to modify the realized breeding density of both species to test other components of the theory. Specifically, I tested for effects of con- and heterospecific competition on life-history decisions of blue and great tits. Finally, I tested whether manipulated breeding densities affected how the two species socially interacted, by studying how both species in each treatment group modified their aggressive behaviour toward con- and heterospecific intruders. I found that there was general and consistent support for the integration between morphology and physiology at different biological levels. However, unexpected discrepancies were observed in the integration of morphology and behaviour, as well as physiology and behaviour. This suggests that species, populations, and sexes respond differently to environmental conditions, and thus exhibit different patterns of phenotypic integration. Additionally, while the nest box manipulation effectively altered the realized breeding densities of blue and great tits, the reproductive traits that I examined were largely unaffected. Finally, blue and great tit males adjusted their aggressive response based on whether they were confronted by a con- vs. a heterospecific intruder but changes in the realized breeding density did not affect aggressiveness. In conclusion, my thesis implies that changes in the social environmental state might impose species-specific costs and benefits of displaying a behavioural response, resulting in different patterns of phenotypic integration observed at different biological levels. Thus, predictions from life-history theory regarding the integration of life-history and behaviour in response to competition may need to incorporate relevant environmental and ecological effects, particularly in the context of intra- and interspecific interactions, to better our understanding of phenotypic integration and the evolution of life-history in the wild.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
• Fakultäten: Fakultät für Biologie
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 19. Juni 2024
• 1. Bericht­erstatter:in: Dingemanse, Niels