Personality drives physiological adjustments and is not related to survival

Abstract

The evolutionary function and maintenance of variation in animal personality is still under debate. Variation in the size of metabolic organs has recently been suggested to cause and maintain variation in personality. Here, we examine two main underlying notions: (i) that organ sizes vary consistently between individuals and cause consistent behavioural patterns, and (ii) that a more exploratory personality is associated with reduced survival. Exploratory behaviour of captive red knots (Calidris canutus, a migrant shorebird) was negatively rather than positively correlated with digestive organ (gizzard) mass, as well as with body mass. In an experiment, we reciprocally reduced and increased individual gizzard masses and found that exploration scores were unaffected. Whether or not these birds were resighted locally over the 19 months after release was negatively correlated with their exploration scores. Moreover, a long-term mark–recapture effort on free-living red knots with known gizzard masses at capture confirmed that local resighting probability (an inverse measure of exploratory behaviour) was correlated with gizzard mass without detrimental effects on survival. We conclude that personality drives physiological adjustments, rather than the other way around, and suggest that physiological adjustments mitigate the survival costs of exploratory behaviour. Our results show that we need to reconsider hypotheses explaining personality variation based on organ sizes and differential survival.

Personality, immune response and reproductive success: an appraisal of the pace‐of‐life syndrome hypothesis

“…The studies challenging the POLS hypothesis often focus on either a single personality, physiology and/or life‐history trait correlated with each other (Bijleveld et al . ; Biro, Adriaenssens & Sampson ; Cole & Quinn ; Krams et al . ; Montiglio et al .…”

“…Studies testing the POLS hypothesis often focus on the relationship between a single personality trait and a single life‐history and/or physiological trait (Bijleveld et al . ; Biro, Adriaenssens & Sampson ; Cole & Quinn ; Krams, Kivleniece, Kuusik, Krama, Freeberg, Mänd, Vrublevska et al . ; Krams, Kivleniece, Kuusik, Krama, Freeberg, Mänd, Rantala et al .…”

Understanding spatial distributions: negative density-dependence in prey causes predators to trade-off prey quantity with quality

“…Because high-quality prey are more difficult to find than low-quality prey, the experience that knots gain feeding on high-quality prey could make it easier for these animals to specialize their feeding [27]. Or they could specialize on more readily available low-quality prey by adapting their physiology to increase processing efficiency.…”

“…Animal personality limits behavioural flexibility and can correlate with individual resource specialization [42,43], which can have important ecological, evolutionary and conservation implications [44]. In knots, personality variation explains variation in gizzard mass, possibly caused by individual specialization on particular prey qualities [27]. The gizzard mass of knots is flexible and, over the course of a week, reflects the quality of its diet [20].…”

“…Nineteen of these birds had been captured on Griend in March 2010 and were released after 1.5 years in captivity, and the other 28 were caught on the nearby islet of Richel (53817 0 N, 5807 0 E, electronic supplementary material, figure S2b) between 2 and 4 August 2011. Before releasing the birds, we measured the size of their muscular stomach (gizzard) with ultrasound [26] as described in detail by [27]. The average gizzard mass was 7 g (2.0 s.d.)…”