University of Groningen Avian Sex Allocation and Ornamental
Total Page：16
File Type：pdf, Size：1020Kb
University of Groningen Avian sex allocation and ornamental coloration Korsten, Peter IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2006 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Korsten, P. (2006). Avian sex allocation and ornamental coloration: A study on blue tits. s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license. More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne- amendment. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 07-10-2021 Avian Sex Allocation and Ornamental Coloration A study on blue tits Peter Korsten Avian Sex Allocation and Ornamental Coloration A study on blue tits The research reported in this thesis was carried out at the Animal Ecology Group which is part of the Centre for Ecological and Evolutionary Studies of the University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands. The research was financially supported by a grant from the Netherlands Organisation for Scientific Research (NWO) awarded to J. Komdeur (ALW grant 810.67.022). Production of this thesis was funded by the University of Groningen, the Centre for Ecological and Evolutionary Studies and Avantes b.v. Lay-out and figures: Dick Visser Cover: Dick Visser, Sander van der Werf Cover photographs: Peter Korsten Other photographs: Peter Korsten, Ingrid Heersche, Ruben Piek, Wobine de Sitter Printed by: Ponsen en Looijen b.v., Wageningen ISBN: 90-367-2841-X RIJKSUNIVERSITEIT GRONINGEN Avian Sex Allocation and Ornamental Coloration A study on blue tits PROEFSCHRIFT ter verkrijging van het doctoraat in de Wiskunde en Natuurwetenschappen aan de Rijksuniversiteit Groningen op gezag van de Rector Magnificus, dr. F. Zwarts, in het openbaar te verdedigen op vrijdag 22 december 2006 om 14.45 uur door Peter Korsten geboren op 22 december 1973 te Zwolle Promotores: Prof. dr. ir. J. Komdeur Prof. dr. R.H. Drent Prof. dr. S. Daan Beoordelingscommissie: Prof. dr. B. Kempenaers Prof. dr. J.M. Tinbergen Dr. C. M. Lessells voor mijn opa, Jan Bosch Contents CHAPTER 1 General introduction 9 Part I – Inheritance of plumage UV coloration CHAPTER 2 Heritable variation in sexually selected structural coloration in blue tits 25 Part II – Female reproductive adjustment to male UV coloration CHAPTER 3 Effectiveness of a commonly-used technique for experimentally 45 reducing plumage UV reflectance CHAPTER 4 Primary sex ratio adjustment to experimentally reduced 55 male UV attractiveness CHAPTER 5 Rapid changes in maternal yolk hormone deposition in response 73 to manipulated male attractiveness Part III – UV coloration as a signal in inter-individual competition CHAPTER 6 UV signalling is not involved in male-male territorial conflict 89 in the blue tit CHAPTER 7 Absence of status signalling by structurally based ultraviolet plumage 107 in wintering blue tits CHAPTER 8 General discussion 125 References 139 Nederlandse samenvatting – Dutch summary 147 Dankwoord – Acknowledgements 167 Addresses of co-authors 173 CHAPTER 1 General introduction CHAPTER 1 This thesis deals with the consequences of the two main problems that virtually all sexually reproducing organisms are facing: i) how to find a suitable mate; and once mated; ii) how much to invest in the production of male versus female offspring. Sexual selection – finding a mate In order to reproduce, organisms that reproduce sexually first need to find a suitable partner, generally of different sex. Individuals bearing genes that enable them to be more successful in attracting or finding mates will propagate their genes into future generations more successfully. This selective process which acts through variation in mating success was first recognised by Darwin (1871) and was named ‘sexual selection’ to distinguish it from ordinary ‘natural selection’ (Andersson 1994). In general, males can potentially fertilize the egg cells of many females with cheaply produced sperm, whereas females have a much smaller reproductive poten- tial. As a consequence, males are generally selected to maximize their number of offspring by maximizing the number of female mates they can obtain, whereas females mostly evolve to select only those males that leave them offspring of the highest quality (Andersson 1994). Note, however, that there are also cases in which these patterns are reversed between sexes (e.g. Berglund & Rosenqvist 1993; Delehanty et al. 1998). The most selective sex in choosing potential mates is often referred to as the ‘choosy sex’ (Andersson 1994). Sexual selection can lead to the evolution of male (and female) exaggerated traits also named ornaments, which improve access to mates either by increased attraction (‘inter-sexual selection’) or better ability to withstand same-sex competi- tors (‘intra-sexual selection’) (Andersson 1994). Examples of sexually selected traits used by males to attract potential female mates are as varied as the chirping songs of crickets (Bentsen et al. 2006), pheromones of mice (Egid & Brown 1989) and the bright and conspicuous plumage colours of many species of bird (Hill 2006). Examples of traits selected by male-male competition over access to females or breeding territories are eye span in stalk-eyed flies (Panhuis & Wilkinson 1999), the enormous body size of male elephant seals (Le Boeuf 1974), antlers in deer (Kruuk et al. 2002, and references therein) and song in birds (Krebs et al. 1978). Often sexually selected traits have a dual function, both in female mate choice and male-male competition (Berglund et al. 1996). Although evidence for female mate choice and male-male competition comes from a broad range of taxa, birds, with their often complex song and bright colours, have traditionally been key models in sexual selection research (Darwin 1871; Hamilton & Zuk 1982; Andersson 1994). The mating behaviour of birds continues to be intensively studied and birds are invariably important as models for testing general principles of sexual selection (e.g. Hadfield et al. 2006; Qvarnström et al. 2006; Figure 1.1). One particular issue, which has received much recent attention, 10 GENERAL INTRODUCTION is the fact that avian colour vision differs in some important respects (e.g. ultraviolet [UV] vision) from human colour perception (Cuthill et al. 2000). This finding has great implications for the study of colour signalling and sexually selected coloration in birds (Bennett et al. 1994). Combined with the recent availability of affordable and light-weight spectrophotometers suitable for measuring plumage reflectance in the field (for a discussion see Andersson & Prager 2006), the recent appreciation of the particular properties of the avian visual system has stimulated a whole new area of research into the role of colour perception and the different colour-producing mechanisms (Box A) in avian sexual selection (reviewed in Hill & McGraw 2006a; Hill & McGraw 2006b). BOX A. Mechanisms of plumage coloration The great diversity in plumage colours of birds is produced by two basic mecha- nisms: 1) light absorption by pigments and 2) coherent light scattering by micro- scopic keratin structures in the feathers (Fox 1976; Prum et al. 1999; Hill & McGraw 2006a). Pigment-based coloration: carotenoids and melanins A wide variety of pigment types are used by birds to produce the diversity of plumage colours. The two most important classes of feather pigments are carotenoids (McGraw 2006) and melanins (Jawor & Breitwisch 2003). Carote- noids mostly cause bright yellow, orange and red colours. For example, carotenoids are responsible for the yellow coloration of the blue tit’s (Parus caeruleus) breast feathers (Partali et al. 1987). Carotenoids cannot be synthesized de novo by birds and thus need to be derived from the food. Carotenoids for feath- er coloration may be limited, because they are often scarce compounds within the diet and also needed for other vital functions of the body such as a well-working immune system (Olson & Owens 1998). Therefore, birds face a trade-off between deposition of carotenoids in the plumage and reservation of these nutri- ents for important physiological activities. As a result of this trade-off carotenoid coloration may be a reliable signal of individual quality, revealing for example the general health or foraging efficiency of a particular individual (Lozano 1994; Olson & Owens 1998). Melanins mostly cause rusty red, brown, grey, and black colours. For exam- ple, the blue tit’s black eye stripe is probably caused by melanins. Birds can newly synthesise melanins in their bodies. It is unclear if this production is costly in terms of for example energy expenditure or use of valuable nutrients. The extent of melanin coloration is often related to individual aggressive behaviour and social dominance (Jawor & Breitwisch 2003). 11 CHAPTER 1 Structurally based coloration White, blue, purple, green, iridescent and UV-reflecting plumage, such as that of the blue tit’s crown feathers (Andersson et al. 1998; Hunt et al. 1998), is mostly structurally based and dependent on the precise arrangement of the microscopic keratin structures in the feather barbs and barbules (Prum et al. 1999).