1. A number of strategies that divert attacks of visually guided predators, such as birds, have evolved multiple times in animals. Detritus web decorations built by certain orb-web spider species are thought to deflect avian predator attacks away from spiders and towards their web decorations. Still, empirical evidence for this function and its adaptive significance is lacking. The orb-web spider, Cyclosa monticola, adorns its web using a linear detritus decoration consisting of moults, egg sacs, prey remains and leaf litters. 2. In the present study, we investigated whether detritus decorations constructed by C. monticola spiders divert attacks of avian predators away from spiders. We first employed colour modelling to compare spider bodies and detritus decoration colouration from the perspective of domestic chicks and blue tits. We then experimentally tested the deflection hypothesis in the laboratory using naïve chicks as predators. We put the chicks in a cage containing a web either with (S+) or without (S−) a spider and either with (D+) or without (D−) detritus decoration (a total of four types of webs: S+D+, S+D−, S−D+ and S−D−) under both natural habitat background and white background. 3. We found that the colour of C. monticola spiders is indistinguishable from that of their detritus decorations for both chicks and blue tits with both backgrounds. Laboratory predation experiments showed that with both backgrounds, chicks attacked the spiders much less frequently when their decorations were present on the webs (S+D+; natural habitat: 20%, white background: 30%) than when their decorations were absent (S+D−; natural habitat: 95%, white background: 85%), resulting in greater spider survival advantage. 4. We also found that the rate of attack of spiders and their decorations was not random; the decorations were more likely to be attacked than spiders, regardless of the ratio of surface area of decorations to spider bodies when both spiders and decorations were presented (S+D+). Therefore, our results support a deflection, rather than concealment hypothesis for web decorations. | 2111 Functional Ecology MA et Al.

How animals assess information encoded in individual color patches have been extensively studied, yet the role of both individual color patches and gross color pattern (i.e., the combination of color patches) remains understudied. We tested the functioning of both individual color patches and gross color pattern in sexual selection using the jumping spider Siler semiglaucus as a study system. We first quantified sexual dimorphism in S. semiglaucus in both individual patches and gross color pattern using the newly developed quantitative color pattern analysis (QCPA) framework. After detecting sexual differences in color coverage and pattern contrast, we manipulated the abdomen color pattern of males and had them engage in both female mate choice and male contest trials. Females spent more time watching males with lower pattern contrast and greater red coverage during mate assessment, suggesting that they evaluate information from both individual patches and gross color pattern of males. However, male color pattern had no significant effect on the outcomes of male contests. Thus, we suggest that the observed sexual color pattern dimorphism evolved primarily through female mate choice in S. semiglaucus. This is the first study to use QCPA framework to quantify sexual dimorphism in within-pattern conspicuousness from an intraspecific perspective in invertebrates. Our study also highlights the importance of both individual color patches and gross color pattern in sexual selection.

Two novel members of the human cAMP-dependent protein kinase inhibitor (PKI) gene family, PKIB and PKIG, were cloned. The deduced proteins showed 70 % and 90 % identity with mouse PKIβ and PKIγ respectively. Both the already identified pseudosubstrate site and leucine-rich nuclear export signal motifs were defined from the 11 PKIs of different species. The PKIB and PKIG genes were mapped respectively to chromosome 6q21-22

Decorating behavior is common in various animal taxa and serves a variety of functions from camouflage to communication. One predominant function cited for decoration is to avoid predators. Conspicuous, disc-like (discoid) silk decorations spun by orb-web Argiope juvenile spiders are hypothesized, among others, to defend spiders against visual predators by concealing spider outlines on the web, deflecting attacks, shielding them from view, or masquerading as bird-droppings. However, the direct evidence is limited for a specific mechanism by which discoid decorations may deter predators. Here we evaluate the mechanisms by which discoid decorations may defend Argiope juveniles against naïve chicks. Using visual modeling, we show that avian predators are able to distinguish spiders from discoid decorations. Using chick predation experiments, we found that the naïve chicks readily pecked any objects, ruling out the possibility of their neophobia. Significantly more chicks attacked spiders when they were exposed to chicks, regardless of whether their webs had discoid decorations, but few chicks attacked spiders when they were behind the decorations. We also found that significantly few chicks attacked decorations when spiders were absent or behind the decorations. We thus conclude that discoid decorations function to deter avian predators by shielding the spider from view or distracting, not by deflecting attacks, concealing the spider’s outline, or masquerading as bird-droppings. This study sheds light on the study of other similar anti-predator strategies, in a wide range of spider species and other animals that use decorating strategies.