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The effect of slower responses to validly than invalidly cued targets is known as inhibition of return (IOR). Opposing accounts of IOR have been proposed: one postulates a singular phenomenon explained by oculomotor mechanisms alone, while the other, more diverse account postulates both perceptual-cognitive and motor factors. In our research we considered the relation between motor programming and IOR. In an extended replication of an earlier study, using an eye abduction technique we restricted eye movement in the temporal half-space; this resulted in IOR attenuation in that area, compared to the unrestricted, nasal part of the visual field. Our results contradict the earlier result and demonstrate that IOR does depend on preparation of eye movement, as predicted by the oculomotor priming hypothesis. [ABSTRACT FROM AUTHOR]

Because of divergent selection acting on males and females arising from different life-history strategies, polyandry can be expected to promote sexual dimorphism of investment into immune function. In previous work we have established the existence of such divergence within populations where males and females are exposed to varying degrees of polyandry. We here test whether the removal of sexual selection via enforced monogamy generates males and females that have similar levels of investment in immune function. To test this prediction experimentally, we measured differences between the sexes in a key immune measurement (phenoloxidase (PO) activity) and resistance to the microsporidian Paranosema whitei in Tribolium castaneum lines that evolved under monogamous (sexual selection absent) vs polyandrous (sexual selection present) mating systems. At generation 49, all selected lines were simultaneously assessed for PO activity and resistance to their natural parasite P. whitei after two generations of relaxed selection. We found that the polyandrous regime was associated with a clear dimorphism in immune function: females had significantly higher PO activities than males in these lines. In contrast, there was no such difference between the sexes in the lines evolving under the monogamous regime. Survival in the infection experiment did not differ between mating systems or sexes. Removing sexual selection via enforced monogamy thus seems to erase intersexual differences in immunity investment. We suggest that higher PO activities in females that have evolved under sexual selection might be driven by the increased risk of infections and/or injuries associated with exposure to multiple males. [ABSTRACT FROM AUTHOR]

Reaction times to targets presented at previously stimulated locations are longer after some time (approx. 300 ms) than to targets presented in new locations. This effect is widely known as Inhibition of Return (IOR). It is typically explained in terms of an inhibitory bias against returning attention to places previously attended to and thus promoting attentional activity elsewhere. Regardless of its attentional character, IOR seems to encapsulate the interaction between two fundamental dimensions of temperament: engaging in versus inhibition and withdrawal from activity. Approaching IOR in this perspective, the question has arisen as to whether individual differences in reactivity as a temperamental trait express themselves in the time course and magnitude of this effect. 90 subjects (30 low, 30 medium and 30 highly reactive individuals) participated in the study. To the best of our knowledge, there are no other studies of individual differences in these parameters of IOR that use saccadic responses to measure its effect on behavior. The results show that in individuals who are higher in terms of their reactivity, IOR starts earlier and continues at the following SOAs but its magnitude is smaller than in less reactive individuals. The results are explained and discussed in light of the Regulative Theory of Temperament. This is the final version of the Abstract which has been accepted in the revised manuscript. • In the study, we used saccadic responses to measure temperamental differences in IOR. • Individual differences in emotional reactivity were discovered in the time course and magnitude of IOR. • In high vs. low reactive individuals, IOR starts earlier but its magnitude is smaller. • Temperament can influence microscale processes and effects evinced in saccadic movements. [ABSTRACT FROM AUTHOR]

Tardigrades are ubiquitous microfauna that act as consumers and predators in soil food webs. Several studies have suggested that tardigrades have great potential to control nematode populations. However, the regulatory function of tardigrades depends on many factors, including their feeding preferences. Yet, tardigrade feeding preferences remain largely unresolved. Therefore, in our experiment, nine predatory tardigrade species were tested for their preferences for three types of microfauna prey (nematodes, rotifers and tardigrades) under controlled laboratory conditions. We also tested whether tardigrade prey preferences can be predicted by selected functional traits (body length and buccal tube dimensions), because such traits are known to be a powerful tool in determining ecological links between organisms. We observed overall avoidance of tardigrades as prey along with preference for nematode prey. The difference in the total consumed number of the three types of prey were attributable to predator species identity, whereas proportional differences in the three types of prey in the diet were attributable to buccal tube length. Buccal tube width, buccal tube width to length ratio and body length lacked the predictive power for feeding preferences of predatory tardigrades. Our results showed that buccal tube length is more informative of tardigrade prey preference than predator species identity and can be used to predict tardigrade feeding preferences. The knowledge of tardigrade feeding preferences is crucial for understanding the role of tardigrades in soil food web. • Prey preference of predatory tardigrades can be estimated by buccal tube length. • The longer the buccal tube, the higher proportion of tardigrades in the diet. • The longer the buccal tube, the lower proportion of nematodes in the diet. [ABSTRACT FROM AUTHOR]

Highlights: [•] Parasites impose strong selection on host immunity, and this may come at a cost to reproduction. [•] We test for genetic trade-offs between immunity, parasite resistance and reproductive traits. [•] We use well-characterized Tribolium castaneum lines that were subject to experimental evolution. [•] We find no trade-offs or altered immunity despite changed reproductive investment in these lines. [•] Fitting Bateman’s principle overall females invest more in immunity and longevity than males. [ABSTRACT FROM AUTHOR]