While these results confirm the regulatory role of the CD region for bis-histidyl hexacoordination, they also suggest that additional sources contribute to fine tune the equilibrium. General significance Globins constitute a ubiquitous group of heme proteins widely found in all kingdoms of life. These findings raise challenging questions regarding the structure-function relationships in these proteins, as bis-histidyl hexacoordination emerges as a novel regulatory mechanism of the physiological function of globins.

Eye movement modelling examples (EMMEs) are instructional videos of a model's demonstration and explanation of a task that also show where the model is looking. EMMEs are expected to synchronize students' visual attention with the model's, leading to better learning than regular video modelling examples (MEs). However, synchronization is seldom directly tested. Moreover, recent research suggests that EMMEs might be more effective than ME for low prior knowledge learners. We therefore used a 2 × 2 between‐subjects design to investigate if the effectiveness of EMMEs (EMMEs/ME) is moderated by prior knowledge (high/low, manipulated by pretraining), applying eye tracking to assess synchronization. Contrary to expectations, EMMEs did not lead to higher learning outcomes than ME, and no interaction with prior knowledge was found. Structural equation modelling shows the mechanism through which EMMEs affect learning: Seeing the model's eye movements helped learners to look faster at referenced information, which was associated with higher learning outcomes.

We investigated the relationship between female choosiness and mating opportunities in the blood sucking bug Rhodnius prolixus. Rhodnius prolixus females exhibit active discrimination behaviour to male mating attempts which delays or prevents copulation. Female rejection behaviours can be beneficial if mating opportunities are readily available and the pool of males varies in their quality. Thus, the benefits of finding a better quality male may override the cost of rejecting a mating opportunity. Since the availability of mating opportunities is affected by the ratio of sexually active males to females, we randomly assigned focal pairs to arenas with a sex ratio biased toward males, females or without other individuals. More females exhibited rejection behaviour when conspecifics were present, however, no differences were found when the sex ratio was biased toward either males or females. We discuss possible explanations for these results and hypothesize about the adaptive function of female rejection behaviour.