Ant-mimicry in some Brazilian salticid and clubionid spiders (Araneae: Salticidae,Glubionidae)*

This paper describes the morphological and behavioural adaptations responsible for ant-like appearance in eight species (genera Zuniga, Synemosyna, Sphecotypus, and Myrmecium) of salticid and clubionid spiders studied in Amazonian and SE Brazil. All ant-mimicking spiders have body and legs thin, and the shiny integument typical of their models. Light horizontal hair bands and constrictions of the cephalothorax and abdomen simulate, respectively, the head-thorax joint and segmented gaster of ants. The petiole and postpetiole of the ants are usually mimicked by a lengthened pedicel, together with a narrowing of the posterior cephalothorax and/or anterior abdomen. The prominent pedipalps of the spiders often simulate ant mandibles, but they may also be strikingly similar to an ant's head. All ant-mimicking spiders walked in a zig-zag ant-like pattern, and frequently raised and moved about the first pair of legs as ‘antennae’. The mimics were found in the same microhabitats (foliage or ground) as their models, and displayed strong avoidance reactions toward the latter both in the field and in captivity. The inoffensive characteristics of the mimics and the noxious traits of their models (strong mandibles, potent sting, hard integument, venomous secretions) strongly suggest that the spiders are Batesian ant-mimics. The detailed structural and behavioural adaptations enhancing ant-mimicry provide strong circumstantial evidence that the selective agents involved must have good visual acuity, and are probably small insectivorous vertebrates (e.g. birds, lizards and toads) or arthropods (e.g. wasps and spiders) which avoid ants.     

Influence of Growth Conditions, Metabolic Inhibitors, and Phenolic Compounds on the ATP Pool in Fomes annosus

The ATP pool of growing fungal mycelia, particularly Fomes annosus, has been determined. The ATP level varied during the different growth phases and correlated with the variations in the economic coefficient. Common uncouplers (at concentrations similar to those used in mitochondrial tests) decreased the ATP pool very rapidly. The size of the pool often fell 50–80% before the O₂ uptake decreased below that of the control and was accompanied by an increasing exudation of inorganic phosphate. Phenolic compounds added to the medium stimulated the lacease activity, generally in combination with a decrease in the ATP level.     

MATING CALLS OF THE IBERIAN MIDWIFE TOADS ALYTES OBSTETRIC ANS BOSCAI AND ALYTES CISTERNASII

ABSTRACT

The mating calls of the Iberian midwife toads, A.o. boscai and A. cisternasii show clear differences. The calls of A.o. boscai have a shorter duration (104.8ms) and a lower fundamental frequency (1.33 kHz) than those of A. cisternasii (172.0 ms and 1.45 kHz), between 12° and 16°C. In both species signal duration was found to be influenced by temperature.     

Isolation and characterization of eight microsatellite loci in Leporinus macrocephalus (Characiformes: Anostomidae) and cross‐species amplification

Leporinus macrocephalus is a species endemic to the Paraguay River basin and an important fishery resource, as well as a valuable species in aquaculture programs. A total of eight polymorphic microsatellite loci were isolated and characterized. A population survey was conducted involving 45 specimens whereby a large number of alleles (range 5–17 among loci), a highly observed (0.1667–0.6129) and an expected (0.6967–0.9448) heterozygosity was detected, indicating its usefulness in population genetics studies. Cross‐species amplification was successful in eight Characiformes species.     

El Niño and dry season rainfall influence hostplant phenology and an annual butterfly migration from Neotropical wet to dry forests

We censused butterflies flying across the Panama Canal at Barro Colorado Island (BCI) for 16 years and butterfly hostplants for 8 years to address the question: What environmental factors influence the timing and magnitude of migrating Aphrissa statira butterflies? The peak migration date was earlier when the wet season began earlier and when soil moisture content in the dry season preceding the migration was higher. The peak migration date was also positively associated with peak leaf flushing of one hostplant (Callichlamys latifolia) but not another (Xylophragma seemannianum). The quantity of migrants was correlated with the El Niño Southern Oscillation, which influenced April soil moisture on BCI and total rainfall in the dry season. Both hostplant species responded to El Niño with greater leaf flushing, and the number of adults deriving from or laying eggs on those new leaves was greatest during El Niño years. The year 1993 was exceptional in that the number of butterflies migrating was lower than predicted by the El Niño event, yet the dry season was unusually wet for an El Niño year as well. Thus, dry season rainfall appears to be a primary driver of larval food production and population outbreaks for A. statira. Understanding how global climate cycles and local weather influence tropical insect migrations improves the predictability of ecological effects of climate change.     

Threatened tadpoles of Bokermannohyla alvarengai (Anura: Hylidae) choose backgrounds that enhance crypsis potential

Crypsis results from a complex interaction among prey coloration, background matching, behaviour and predator visual perception. Tadpoles are known to have varied adaptations to escape predation, but the use of crypsis is little explored, although it is likely for certain species. We investigated potential escape mechanisms related to active escape (fleeing) and crypsis improvement in Bokermannohyla alvarengai tadpoles, proposing a new method to measure cryptic potential. We studied the range of distances covered by threatened and fleeing tadpoles and the proportion of tadpoles that seek shelter or remain exposed after fleeing. We hypothesized that tadpoles that remain exposed may use alternative strategies to avoid detection, such as reaching deeper microhabitats or positioning themselves on substrates that confer greater crypsis than the ones they were on before disturbance. A significantly greater proportion of tadpoles remained exposed after disturbance and positioned themselves on backgrounds that offered greater cryptic potential, but did not differ in depth. Tadpoles may respond to a trade‐off between sheltering and being cryptic. On the one hand, they may remain close to retreat sites or they may escape to microhabitats that provide appropriate background matching as a means to achieve crypsis. On the other hand, the absence of matching backgrounds in the tadpoles' vicinities may induce them to seek shelter. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 437–446.