Paulo J. Fonseca

Tectonics of the Beja-Acebuches Ophiolite: a major suture in the Iberian Variscan Foldbelt

The Beja-Acebuches Ophiolitic Complex (BAOC) (south Portugal/Spain) corresponds to a high grade metamorphic belt along the boundary between Ossa-Morena and the South Portuguese Zones and comprises a lithostratigraphic sequence including (from top to bottom) metabasalts, (metamorphosed) multiple dyke intrusions in gabbro, flasergabbros and metaserpentinites. It is affected by three deformation phases. D1 affects the ophiolite lower stratigraphic units and is represented by a mylonitic cleavage with a stretching lineation where shear criteria indicates the sense of shear to be towards the north-north-east; this deformation event can be related to the ophiolite emplacement above the crystalline footwall of the Serpa antiform, affecting Precambrian basement and Cambrian cover rocks. The obduction polarity ist north-eastwards, similar to the subduction polarity that generates the Beja Gabbroic Complex (BGC), implying a flake geometry. The second deformation phase, D2, is represented by an intense WNW-ESE sinistral shear event which is responsible for the shattered appearance of the suture; D2 is reactivated later by a more brittle D3 event involving thrusting to the south-west, again with a sinistral component. 40Ar/39Ar isotopic ages were obtained for (metamorphosed) multiple dyke intrusions in the BAOCs gabbro (342.6 ± 1.4 Ma), for metagabbroic cumulates (340.7 ± 1.9 Ma), and for the undeformed/unmetamorphosed BGC (341.1 ± 1.3 Ma) occurring to the north of the ophiolitic suture. These ages reflect a last regional cooling event in the area which post-dates the ophiolite emplacement and the intrusion of the BGC through this oceanic sequence.

Lusitanian toadfish song reflects male quality

SUMMARY Lusitanian toadfish males that provide parental care rely on acoustic signals (the boatwhistle) to attract females to their nest. We test the hypothesis that male quality, namely male size and condition that are relevant for parental success, is reflected in vocal activity and boatwhistle characteristics and thus advertised to females. We recorded 22 males over a week during the peak of the breeding season. Calling rate and calling effort (percentage of time spent calling) strongly reflected male condition (lipid content of somatic muscles) and to a smaller extent sonic muscle hypertrophy and larger gonads. Males in better condition (increased body lipid and relative higher liver mass) also contracted the sonic muscles at faster rate as shown by the shorter boatwhistle pulse periods. Amplitude modulation reflected the degree of sonic muscle hypertrophy. None of the measured male quality parameters were good predictors of boatwhistle duration and dominant frequency. Altogether this study strongly suggests that Lusitanian toadfish males advertise their quality to females primarily with boatwhistle calling rate and calling effort, which mainly reflect male condition. Because pulse period had low variability, consistent with the existence of a vocal central pattern generator, we suggest that males that sustain sonic muscles contraction at a very fast rate close to their physiological limit may be honestly advertising their quality (condition). Similarly, males that produce boatwhistles with higher amplitude modulation, a feature that seems dependent on sonic muscle hypertrophy, could be more attractive to females.

The Moura Phyllonitic Complex: An Accretionary Complex related with obduction in the Southern Iberia Variscan Suture

The structure of the southernmost domain of the Ossa Morena Zone in Portugal (south sector of the Iberian Autochthonous Terrane) is strongly controlled by earlier deformation events. The first two deformation events correspond to tangential strain regimes, marked by subhorizontal milonitic foliations. These events seem to be directly related with the obduction/subduction process during the Variscan ocean closure and the emplacement of the Beja-Acebuches Oceanic Terrane. In this domain (Évora-Beja Domain), the upper tectono-stratigraphic unit (Moura Phyllonitic Complex) is mainly represented by phyllites and corresponds to a strongly imbricated complex, involving several layers of autochthonous sequence (mainly rocks of a volcano-sedimentary complex), but it also includes dismembered and scattered slices of ophiolites. The widespread greenschists facies overprint an earlier high-pressure metamorphic event (blueschists in the central sector of Évora-Beja Domain and eclogites in the western sector). With regard to its geochemical signature, the Moura Phyllonitic Complex includes amphibolites ranging from N-MORB to T/P-MORB (ophiolitic slices) and mafic alkaline and peralkaline metavolcanics (autochthonous slices). At macroscopic scale, the autochthonous sequence of the Évora-Beja Domain is almost complete in the eastern region, with a stratigraphic sequence ranging from Precambrian to Silurian/Lower Devonian. Towards WSW, the Moura Phyllonitic Complex progressively become tectonically discordant on the sequence below, just near the suture, where it superposes Precambrian levels. The overall evidences (tectonic, metamorphic and geochemical) allow the conclusion that the Moura Phyllonitic Complex is an accretionary complex related with the obduction process during earlier times of the variscan ocean closure.

How cicadas interpret acoustic signals.

The vertebrate ear can analyse the frequency components of sound with high resolution, recognizing complex acoustic signals even against a noisy background. By contrast, insect ears can separate only broad-frequency bands, resulting in a categorical perception of sound. We have discovered an insect, the cicada Tettigetta josei, that has a capacity for fine- frequency resolution, which could explain the evolution of frequency-modulated communication signals in cicadas.

Courtship and agonistic sounds by the cichlid fish Pseudotropheus zebra.

Courtship and agonistic interactions in an African cichlid species present a richer diversity of acoustic stimuli than previously reported. Male cichlids, including those from the genus Pseudotropheus (P.), produce low frequency short pulsed sounds during courtship. Sounds emitted by P. zebra males in the early stages of courtship (during quiver) were found to be significantly longer and with a higher number of pulses than sounds produced in later stages. During agonistic intrasexual quiver displays, males produced significantly longer sounds with more pulses than females. Also, male sounds had a shorter duration and pulse period in courtship than in male-male interactions. Taken together, these results show that the acoustic repertoire of this species is larger than what was previously known and emphasize the importance of further research exploiting the role of acoustic stimuli in intra- and interspecific communication in African cichlids.

Characteristics of the acoustic signals in nine species of Cicadas (Homoptera, Cicadidae)

ABSTRACT Detailed descriptions of the acoustic signals of European cicadas are available only for a few species. In this paper the acoustic signals and biomechanics of the timbals in nine species of cicadas from Portugal have been examined. Those species are Cicada barbara lusitanica (Boulard, 1982), C. orni (Linnaeus, 1758), Tettigetta argentata (Olivier, 1790), T. atra (Gomez-Menor, 1957), T. estrellae (Boulard, 1982), T.josei (Boulard, 1982), Tibicina quadrisignata (Hagen, 1855), Tympanistalna gastrica (Stal, 1854), and one unidentified species of Tettigetta. A qualitative and quantitative description of the sound is given in the time domain and the frequency domain. An acoustic male-to-male interaction signal that ceases the courtship was identified in C. barbara lusitanica. Some evolutionary aspects related to the biomechanics of the timbals and to the sounds produced are discussed.

Auditory perception: How cicadas interpret acoustic signals

The vertebrate ear can analyse the frequency components of sound with high resolution, recognizing complex acoustic signals even against a noisy background. By contrast, insect ears can separate only broad-frequency bands, resulting in a categorical perception of sound. We have discovered an insect, the cicada Tettigetta josei, that has a capacity for fine- frequency resolution, which could explain the evolution of frequency-modulated communication signals in cicadas.

Painted gobies sing their quality out loud: Acoustic rather than visual signals advertise male quality and contribute to mating success

Summary Females use multiple cues from different sensory modalities to choose males of high phenotypic or genetic quality to mate with. Fish may use visual and acoustic communication during mating, but few studies have associated multimodal signals with male quality and reproductive success. We examined whether visual and acoustic courtship signals reflect male quality and influence mating success in the painted goby (Pomatoschistus pictus), a highly visual and vocal fish species with paternal care. Painted gobies make conspicuous courtship visual displays such as body quivering and eight-shaped swimming patterns and two types of sounds: drums that are composed of a sequence of low-frequency pulses and a thump-like non-pulsed sound. We predicted that both sensory modalities would advertise male size and condition and influence mating success. We found that larger number of pulses in a drum, lower fatigue (where fatigue is the increase in pulse period during drum production) and higher drum absolute amplitude levels were good predictors of larger male size. Males with high condition factor (Fultons K) showed high drumming activity and low thumping and visual courtship levels. Drumming activity was a good predictor of male fat reserves. Males that succeeded to mate emitted sounds with higher number of pulses and longer pulse periods and showed higher drumming but lower thumping activity than unsuccessful males. All traits (except pulse period) reflected higher male Fultons K or fat reserves, suggesting that females are selecting for male condition. Neither male size nor visual courtship was apparently used in mate selection. Contrary to our expectations, females did not seem to prefer larger or vigorous visually displaying males but chose mates in better condition using multiple cues of drumming sounds. We suggest that preference for high mate condition is related to preference for increased parental ability and hatching success in species with paternal care. To the best of our knowledge, this is the first study that addresses the relative role of signals from different sensory modalities including acoustics, in advertising male quality and in contributing to reproductive success in fish.

Sound radiation in a cicada: the role of different structures

Sound radiation was studied in males of Tympanistalna gastrica St»l during a spontaneous song with the characteristics of the conspecific calling song, which was elicited as an after effect of brain stimulation. The song contains two different kinds of sound pulses: 1) loud clicks and 2) soft pulses, presenting different spectra.The timbals, abdomen, tympana, folded membranes and opercula were tested as potential radiators of the song. The experiments included: 1) probe microphone measurements of the spectra of loud clicks and soft pulses in several positions around the animal and close to the body surface; 2) measurements of the spectra before and after covering with vaseline different structures that might be relevant to the radiation of the song, and manipulations of the size and shape of the abdominal and thoracic portions of the tracheal air sac; 3) laser vibrometry measurements in different parts of the body, both during singing and external sound stimulation.The data obtained demonstrate that several structures contribute differently to the radiation of clicks and soft pulses: 1) The timbals are the main radiators at frequencies around the dominant spectral peak, 10–11 kHz in clicks and 12–13 kHz in soft pulses; 2) The tympana are important in radiation of frequencies below and above the timbal peak, especially during the generation of soft pulses; 3) The abdomen is more activated during the generation of clicks, and is more important in the radiation of low frequencies around 5 kHz.Manipulations of the body cavities showed that neither the thoracic nor the abdominal portions of the air sac are critical for the song tuning. The large abdominal cavity do not seem to work as a Helmholtz resonator. We found no evidence that resonances inside this cavity should play an important role in enhancing sound radiation in T. gastrica.

Temperature dependence of cicada songs (Homoptera, Cicadoidea).

Abstract. The songs of male Portuguese cicadas Tettigetta argentata, T. josei and Tympanistalna gastrica were recorded at five to seven temperatures within the range 24–38.5°C. To investigate the temperature dependence of the neuromuscular apparatus involved in song production, different temporal elements of the calling songs were measured. We report a strong temperature dependence for the syllable and the echeme rates in T. josei and Ty. gastrica. This suggests that in these species the neuromuscular structures involved in the timbal cycle and in generating the echeme succession of the song are strongly temperature dependent. In T. argentata, the syllable rate was again significantly temperature dependent; the echeme rate, however, increased between 25.5°C and 33.5°C but decreased with the highest temperature. This indicates that at least in T. argentata two separate neuronal networks control both song parameters. Other temporal elements of the song with potential behavioural significance were also measured and found to be temperature dependent (e.g. echeme duration and interval). The possible implications for intraspecific communication are discussed. We also demonstrate that the temperature of these small cicadas is not significantly influenced by the muscle activity involved in song production. On the other hand, exposure to sunlight can be used by these cicadas to elevate their body temperature by more than 10°C.