No abstract

Plant growth is sustained by two complementary processes: biomass biosynthesis and cell expansion. The cell wall is crucial to both as it forms the majority of biomass, while its extensibility limits cell expansion. Cellulose is a major component of the cell wall and cellulose synthesis is pivotal to plant cell growth, and its regulation is poorly understood. Using periodic diurnal variation in Arabidopsis thaliana hypocotyl growth, we found that cellulose synthesis and cell expansion can be uncoupled and are regulated by different mechanisms. We grew Arabidopsis plants in very short photoperiods and used a combination of extended nights, continuous light, sucrose feeding experiments, and photosynthesis inhibition to tease apart the influences of light, metabolic, and circadian clock signaling on rates of cellulose biosynthesis and cell wall biomechanics. We demonstrate that cell expansion is regulated by protein-mediated changes in cell wall extensibility driven by the circadian clock. By contrast, the biosynthesis of cellulose is controlled through intracellular trafficking of cellulose synthase enzyme complexes regulated exclusively by metabolic signaling related to the carbon status of the plant and independently of the circadian clock or light signaling.

to different conditions. However, sheer costs of flexibility cannot explain the polymorphism 22 created by personality variation. In a correlative approach, we here tested whether mate 23 choice might act as a major driving force maintaining personality variation in the 24 monogamous, biparental rainbow krib, Pelvicachromis pulcher. We personality-typed all 25 males and females for their boldness (activity under simulated predation risk) and allowed 26 females to choose between two males that differed in their boldness (behavioural level and 27 consistency). Prior to the choice, females were allowed to observe both males, expressing 28 their natural boldness towards a video animated natural predator. Both sexes showed 29 personality differences in boldness over the short-and long-term. Furthermore, when 30 removing side-biased females, we found a dis-assortative mating preference for the 31 behavioural level and an assortative preference for behavioural consistency in boldness. 32Such preference patterns might facilitate effective parental role allocation during offspring 33 care and/or provide genetic benefits. Our results suggest that sexual selection plays an 34 important role in the evolution of personality differences. 35 36 Keywords: anti-predator behaviour, assortative, behavioural compatibility, cichlid, mate 37 choice, Pelvicachromis pulcher, personality, risk-taking, sexual selection, side bias 38 39 3 Individuals have to cope with a wide array of environmental challenges. Therefore, 40 flexibility in the expression of behavioural responses towards different and changing 41 conditions should be favoured by selection ). Yet, individuals often show 42 considerable consistent between-individual differences in behaviour over time and/or 43 contexts (Boissy, 1995). Such personality differences are common throughout the animal 44 kingdom (reviewed in Gosling, 2001; Kralj-Fišer et al., 2014) and have been shown for 45 various behavioural traits, such as activity pattern, aggressiveness, exploratory tendencies, 46 boldness and fearfulness (reviewed in Dall et al., 2004; Gosling, 2001;. 47Personality traits are moderately heritable (Ariyomo, Carter, et al., 2013; Patrick et al., 48 2013;Reif et al., 2003;van Oers et al., 2005) and have fitness consequences (e.g. Ariyomo et 49 al., 2012; Dingemanse et al., 2005;Smith et al., 2008), suggesting they are not merely non-50 adaptive noise that surrounds an adaptive optimum (Wilson, 1998). Nevertheless, 51 underlying mechanisms that generate and maintain behavioural polymorphism are largely 52 unclear and many aspects of the growing body of theoretical frameworks still remain to be 53 empirically tested (reviewed in e.g. Schuett et al., 2010;Wolf et al., 2010). 54 55 Recently, Schuett et al. (2010) pointed out that sexual selection may be important in 56 generating and maintaining personality variation though this possibility has rarely been 57 tested (but see e.g. Montiglio et al., 2016;. According to the proposed 58 framework , personalities are expected to p...

In this study, population level lateralisation and the suitability of mirror tests as a test of natural aggressive behaviour in male rainbow kribs Pelvicachromis pulcher was investigated. Aggressive behaviour in live agonistic trials correlated positively with behaviours towards a mirror image and no visual lateralisation was detected.

Virtual stimuli represent an increasingly popular tool in the study of animal behaviour. Modern techniques have the potential to simplify and improve traditional experiments using live stimuli. However, the increasing availability of diverse techniques is associated with problems and limitations. Although many new methods have been developed, their validation remains largely untested. In the present study, we therefore performed two experiments to test whether 2‐D animations of predators and conspecifics elicit biologically appropriate behavioural responses in male rainbow kribs, Pelvicachromis pulcher. Individual responses towards a sympatric natural fish predator, Parachanna obscura, were tested using live predators and still colour photographs, animated using PowerPoint©. Compared to control trials (empty aquarium and white computer screen, respectively), individuals decreased their activity in response to both live and animated predators. We found no difference in activity between live and animation trials. Further, we tested individual aggression (frequency of aggressive behaviours) exhibited towards live and animated conspecifics. Individual aggressive behaviours shown towards live and animated conspecifics were positively correlated. Moreover, an individual's mean distance towards the opponent was a suitable proxy for individual aggression permitting the facilitation and standardisation of an individual's aggression through the use of a tracking software compared with the more laborious, traditional manual assessment. Our results show that simple, inexpensive animation techniques have the potential to provide an easy‐to‐apply and useful technological advance in animal behaviour research.