Current Issue

Many animals form roosting aggregations for defensive benefits, such as early warnings and reduced capture probability. These benefits may vary depending on the individual’s location within the aggregation and its phenotypic condition. In the lowland rainforest of Costa Rica, Opiliones of Prionostemma Pocock, 1903 (Sclerosomatidae) form daytime roosting aggregations, and leg loss occurs in over half of the individuals. We tested whether the leg condition (intact or missing at least one leg) in one species (P. sp.2) affects roosting location within the group by experimentally inducing the formation of aggregations overnight. We found that autotomized individuals (with , eight legs) roosted more frequently (29%) in the center of groups than intact (eight-legged) individuals (20%). This finding suggests that leg loss may influence individuals to select more protected positions within the group. These arachnids might modify their aggregation behavior to compensate for the reduced locomotor performance and potential reduced sensory performance that derives after leg loss. Broadly, our work provides novel experimental data on how variable phenotypic conditions affect the decisions animals make while engaging in group living

The scent gland secretion of a cladonychiid harvestman from Europe, Peltonychia clavigera (Simon, 1879) (Opiliones, Laniatores, Travunioidea), was investigated by gas chromatography–mass spectrometry. The exudates contained N,N-dimethyl-2-phenylethan-1-amine and various alkylpyrazines, being clearly different from the tobacco alkaloid-type that is known from other European Travunioidea. The N,N-dimethyl-2-phenylethan-1-amine-type has so far been regarded as characteristic for western North American species only. Regarding the wide taxonomic distribution of N,N-dimethyl-2-phenylethan-1-amine and tobacco alkaloids across representatives of Travunioidea, we consider both groups of compounds phylogenetically old chemical characters of Travunioidea, having evolved before the separation of North America and Europe in the Eocene.

Temperature is a major environmental factor shaping offspring phenotype in ectotherms. The temperatures experienced during development can influence a suite of life history and behavioral traits including developmental time, size, growth rate, and locomotor performance. Consequently, phenotypic variation caused by the thermal conditions experienced during embryonic development may have long-term implications on survival and fitness. Female wolf spiders carry their egg sacs throughout the incubation period, which allows them to move developing embryos between different microhabitats. In this work, we investigate temperature preference and movement behavior of the wolf spider Hogna antelucana (Montgomery, 1904) in different reproductive states. We find that brooding females thermoregulate with greater precision and at lower average temperatures than non-brooding females. Additionally, brooding females move more and have longer movement bouts compared to non-brooding females. Our findings support one of the leading hypotheses for why wolf spiders carry egg sacs, which is to preferentially select temperatures for optimal embryonic development.