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Vasconcelos R.O.,University of Lisbon | Fonseca P.J.,University of Lisbon | Amorim M.C.P.,Unidade de Investigacao em Eco Etologia | Ladich F.,University of Vienna
Proceedings of the Royal Society B: Biological Sciences | Year: 2011

Many fishes rely on their auditory skills to interpret crucial information about predators and prey, and to communicate intraspecifically. Few studies, however, have examined how complex natural sounds are perceived in fishes. We investigated the representation of conspecific mating and agonistic calls in the auditory system of the Lusitanian toadfish Halobatrachus didactylus, and analysed auditory responses to heterospecific signals from ecologically relevant species: a sympatric vocal fish (meagre Argyrosomus regius) and a potential predator (dolphin Tursiops truncatus). Using auditory evoked potential (AEP) recordings, we showed that both sexes can resolve fine features of conspecific calls. The toadfish auditory system was most sensitive to frequencies well represented in the conspecific vocalizations (namely the mating boatwhistle), and revealed a fine representation of duration and pulsed structure of agonistic and mating calls. Stimuli and corresponding AEP amplitudes were highly correlated, indicating an accurate encoding of amplitude modulation. Moreover, Lusitanian toadfish were able to detect T. truncatus foraging sounds and A. regius calls, although at higher amplitudes. We provide strong evidence that the auditory system of a vocal fish, lacking accessory hearing structures, is capable of resolving fine features of complex vocalizations that are probably important for intraspecific communication and other relevant stimuli from the auditory scene. © 2010 The Royal Society.

Levy A.,Unidade de Investigacao em Eco Etologia | von der Heyden S.,Stellenbosch University | Floeter S.R.,Federal University of Santa Catarina | Bernardi G.,University of California at Santa Cruz | Almada V.C.,Unidade de Investigacao em Eco Etologia
Molecular Phylogenetics and Evolution | Year: 2013

A molecular phylogeny of 15 (out of 26 recognized) species of Parablennius Miranda Ribeiro, 1915 was constructed based on two mitochondrial and two nuclear gene fragments, and using maximum parsimony, maximum likelihood and Bayesian approaches. The closely related genera Hypleurochilus, Salaria and Scartella were also studied to ascertain their relationship with Parablennius. Phylogenetic analyses were compared with morphology-based taxonomical studies. Hypleurochilus, Salaria and Scartella appear well supported within a clade including all Parablennius, indicating that this genus is paraphyletic. The species pairs P. parvicornis-P. sanguinolentus and P. gattorugine-P. ruber are well-supported and relatively distant from remaining Parablennius. Remaining Parablennius form two distinct well-supported groups: (1) a clade of Atlantic-Mediterranean Parablennius (P. pilicornis, P. marmoreus, P. rouxi, P. salensis and P. tentacularis); (2) a clade including Hypleurochilus, the Indo-Western Pacific Parablennius (P. cornutus, P. intermedius, P. tasmanianus and P. yatabei) and the Atlantic-Mediterranean P. incognitus and P. zvonimiri. Use of a relaxed molecular clock suggests that Indo-Pacific Parablennius originated recently from an Atlantic Parablennius that may have dispersed via southern Africa, rather than via the Tethys seaway. © 2012 Elsevier Inc.

Goncalves A.R.,Unidade de Investigacao em Eco Etologia | Goncalves A.R.,Abel Salazar Biomedical Sciences Institute | De Sousa L.C.,Abel Salazar Biomedical Sciences Institute | Almada V.C.,Unidade de Investigacao em Eco Etologia
Applied Animal Behaviour Science | Year: 2012

The dominance hierarchies and the growth rate of the commercially important fish Diplodus sargus were assessed in this study. Specifically, we tested the hypothesis that, if stable dominance orders were established, dominant fish would grow faster and show better condition factors than losers at the end of the experiment. Eight groups of six individuals were followed for 6 weeks and, for each group, we measured the linearity of the hierarchies on a weekly basis, and the week to week stability of the hierarchical structures. These dominance structures were linear and stable from week to week. We found no significant correlation between the dominance index with either growth rate or final condition factor. Thus, in short time windows over few weeks, aggressive competition seems not to cause differences in growth, although effects at a longer term like those induced by stress cannot be ruled out. © 2012 Elsevier B.V.

van der Sluijs I.,McGill University | Gray S.M.,McGill University | Amorim M.C.P.,Unidade de Investigacao em Eco Etologia | Barber I.,University of Leicester | And 8 more authors.
Evolutionary Ecology | Year: 2011

Fish populations are increasingly being subjected to anthropogenic changes to their sensory environments. The impact of these changes on inter- and intra-specific communication, and its evolutionary consequences, has only recently started to receive research attention. A disruption of the sensory environment is likely to impact communication, especially with respect to reproductive interactions that help to maintain species boundaries. Aquatic ecosystems around the world are being threatened by a variety of environmental stressors, causing dramatic losses of biodiversity and bringing urgency to the need to understand how fish respond to rapid environmental changes. Here, we discuss current research on different communication systems (visual, chemical, acoustic, electric) and explore the state of our knowledge of how complex systems respond to environmental stressors using fish as a model. By far the bulk of our understanding comes from research on visual communication in the context of mate selection and competition for mates, while work on other communication systems is accumulating. In particular, it is increasingly acknowledged that environmental effects on one mode of communication may trigger compensation through other modalities. The strength and direction of selection on communication traits may vary if such compensation occurs. However, we find a dearth of studies that have taken a multimodal approach to investigating the evolutionary impact of environmental change on communication in fish. Future research should focus on the interaction between different modes of communication, especially under changing environmental conditions. Further, we see an urgent need for a better understanding of the evolutionary consequences of changes in communication systems on fish diversity. © 2010 Springer Science+Business Media B.V.

Vasconcelos R.O.,University of Lisbon | Simoes J.M.,Unidade de Investigacao em Eco Etologia | Almada V.C.,Unidade de Investigacao em Eco Etologia | Fonseca P.J.,University of Lisbon | Amorim M.C.P.,Unidade de Investigacao em Eco Etologia
Ethology | Year: 2010

Male signals are frequently studied in a single behavioral context, but in some cases they may assist multiple functions, namely for both male-male competition and female mate choice. Boatwhistles are known as the mate attraction calls of toadfishes typically produced during the breeding season. However, recent observations with the Lusitanian toadfish Halobatrachus didactylus (Batrachoididae) indicate that the emission of boatwhistles is not restricted to this period, which suggests a function in other behavioral contexts such as agonistic territorial interactions. We experimentally manipulated the social context of toadfish males to investigate whether boatwhistles are produced during territorial defense, by introducing 'intruders' in an experimental tank containing nesting 'resident' males. Furthermore, we examined whether parental care (eggs in the nest) affected the behavioral responses of resident males during territorial defense. Resident males defended their shelters producing sounds, mostly boatwhistles, towards intruders. Parental males revealed higher aggression levels, exhibiting additional threatening and attack behaviors. Boatwhistles registered during agonistic events were compared with the mate advertising boatwhistles recorded from small aggregations of nesting males in a natural breeding intertidal area. Agonistic boatwhistles were produced in lower and variable calling rates comparing with the advertising ones that were typically emitted in long series of calls. Agonistic boatwhistles were similar in duration and frequency harmonic structure (with a middle tonal phase) to the advertising calls, but presented less amplitude modulation, and lower dominant and fundamental frequencies. These acoustic differences were probably related to differences in calling rates and broadcast demands associated to the distance to the intended receiver. We provide first evidence that, apart from attracting mates, the toadfish boatwhistles also function as active 'keep-out' signals during territorial defense. © 2010 Blackwell Verlag GmbH.

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