Does sexual selection favour consistent behavioural differences in biparental cichlids?
Final Report Abstract
Individuals within a population or species often vary consistently in common behavioural traits. Why do such personality differences exist, given that evolutionary rationale suggests that individuals should be flexible in their behaviour and adjust their behavioural expression according to current situations? One potential explanation, that has rarely been considered empirically, is that animal personalities are subject to sexual selection. Here, we set out to test the role of sexual selection in generating and maintaining the two aspects of animal personality: inter-individual variation in the level of behaviour and variation in (intra-individual) behavioural consistency using a biparental and territorial cichlid, Pelvicachromis pulcher, as model system. Our research had four main objectives: we aimed to assess whether (1) there is a link between female mate choice and personality; (2) there is a link between male mate choice and personality; (3) mate choice patterns on the basis of personality differences have reproductive benefits; (4) personality and parental care behaviours are linked and hormonally controlled. We considered aggression and risktaking to be important during mate choice and parental care in rainbow kribs because both behaviours affect offspring and territory defence. To achieve our objectives, we conducted six experiments; an additional four methodological experiments were carried out to test and verify the suitability of the methods used. In our methodological studies we showed experimentally, that mirror tests as well as 2D-animations of same-sex opponents are suitable to assess aggressive behaviour in P. pulcher; that 2D-animations of natural predators offer an effective way of assessing personality differences in risktaking behaviour without posing actual threads to individuals, and that individual colour-marks do not interfere with natural ornaments during mate choice. In a series of mate choice experiments, we tested whether natural or manipulated behavioural differences in risk-taking and aggression (level and consistency, respectively) are important during mate choice. In addition, we tested the importance of personality variation in either sex and in their combination for parental care and reproductive success in a large breeding experiment. Our experiments showed that male and female rainbow kribs show personality differences in risk-taking and aggressive behaviour. We found that behaviour, in particular risk-taking, is important during female (but not male) mate choice per se. We found support for either disassortative mating (correlative female choice study) or directional female choice (manipulative experiment) for male risk-taking. These results were biologically relevant in that male risk-taking behaviour and the combination of male and female risk-taking had reproductive consequences. Our results indicate that depending on the conditions, it might pay for females to agree in choice for risk-taking behaviour (to produce larger broods) or to trade-off between brood size versus reproducing per se. It is possible that the trade-offs differ for shyer and bolder females leading to disassortative mate choice patterns in some situations. Our results further suggested that male risk-taking behaviour may be modulated by testosterone and 11-keto-testosterone and that the combination of hormonal profiles of parents are tightly linked to care coordination. Our project was successful by achieving all aims and providing novel insights into the link between sexual selection and personality differences.
Publications
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(2020) Do female rainbow kribs choose males on the basis of their apparent aggression and boldness? A non-correlational mate choice study. Behav Ecol Sociobiol (Behavioral Ecology and Sociobiology) 74 (3) 34
Scherer, Ulrike; Godin, Jean-Guy J.; Schuett, Wiebke
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(2016). Lateralisation in agonistic encounters: Do mirror tests reflect aggressive behaviour? A study on a West African cichlid. Journal of Fish Biology 89 (3), 1866-1872
Scherer, U, Buck, M & W Schuett
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(2017). Artificial Visible Implant Elastomer (VIE) tags of different colour and symmetry do not influence mate choice in a cichlid. Behaviour 154, 387-402
Schuett, W, Nava, TF, Rahmlow, N & U Scherer
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(2017). Different or alike? Female rainbow kribs choose males of similar consistency and dis-similar level of boldness. Animal Behaviour 128, 117-124
Scherer, U, Kuhnhardt, M & W Schuett
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(2017). Validation of 2D-animated pictures as an investigative tool in the behavioural sciences – a case study with a West African cichlid fish, Pelvicachromis pulcher. Ethology 123 (8), 560-570
Scherer, U, Godin, J-G J & W Schuett
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(2018). No male mate choice for female boldness in a biparental West African cichlid, the rainbow krib (Pelvicachromis pulcher). PeerJ 6:e5373
Scherer, U & W Schuett
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(2018). Predictability is attractive: Female preference for behaviourally consistent males but no preference for the level of male aggression in a bi-parental cichlid. PLoS ONE 13(4): e0195766
Scherer, U, Kuhnhardt, M & W Schuett
