CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S15
MEMRI of the olfactory pathway into the frog brain Xenopus
laevis
Renaud Boistel 1,4 , Brigitte Gillet 2 , Christelle PO 2 , Anthony
Sébillot 3 , Peter Cloetens 4 , André Mazabraud 5 , Nicolas Pollet 5
S15 - Integrative biology of acoustic communication
1 Muséum National d’Histoire Naturelle, UMR 7179 Mécanismes
Adaptatifs : des Organismes aux Communautés, Département
Ecologie et Gestion de la Biodiversité, 57, rue Cuvier CP55, F-
75021 Paris cedex 05, France
2 Laboratoire de RMN Biologique, ICSN, CNRS, Gif-sur-Yvette,
France
3 WatchFrog S.A.S. RCS Evry 484 872 551, Code APE 731 Z
4 European Synchrotron Radiation Facility,, B.P. 220, F-38043
Grenoble, France
5 CNRS UMR 8080, Bât. 445, Université Paris XI, 91405 Orsay,
France
In terrestrial frogs, metamorphosis involves a shift in olfaction from
sensing chemicals in water to detecting airborne odours. Some
frogs such as Xenopus have an aquatic life and the structure of
their olfactory organ is therefore the subject of considerable
interest as genetic models. In adult Xenopus, the principal cavity is
always filled with air, even when the frog is submerged. On the
other hand, the vomeronasal organ is filled with fluid throughout
life. Xenopus is reported to be able to find its way to new ponds
over distances of several kilometres. The only available cue seems
to be olfaction. This is supported by Du Plessis (1966) who
suggested that one function of smelling airborne odours may be in
locating pond habitats. Knowledge on the detection of odours from
the air is lacking. We aim to investigate airborne olfaction in
Xenopus laevis in vivo by a novel method, Manganese-enhanced
Magnetic Resonance Imaging (MEMRI). We obtained a good T1
contrast in the afferent projection and the olfactory bulb during time.
MEMRI proves to be useful and offers new perspectives as a
molecular imaging method to visualize functional neural circuits in
the brain in vivo.
Vocal communication in groups of neighbouring skylarks
(Alauda arvensis): syntax always matters?
Elodie Briefer, Fanny Rybak and Thierry Aubin
Université Paris 11, NAMC, CNRS-UMR8620, Bioacoustics Team,
Bat. 446, 91405 Orsay cedex, France
The skylark is a territorial species of open landscape in which pairs
settle in stable territories during the breeding season. Due to the
heterogeneity of the habitat, territories are gathered in patches
spaced by few kilometres. Males produce complex songs as a part
of the territorial behaviour. We showed that, in a given patch,
males (neighbours) share several sequences of syllables in their
songs, whereas males settled in different patches (strangers) have
no sequences in common. To test the hypothesis that these
shared sequences support a group signature, we made playback
experiments with ‘chimeric’ signals: songs of strangers where the
sequences shared by neighbours were artificially inserted.
Behavioural responses to playbacks indicated a reduced
aggression toward neighbour songs compared to stranger ones.
Furthermore, the same level of responses, observed when a
‘chimeric’ and a neighbour song were broadcast, indicated that
shared sequences are recognised as markers of the
neighbourhood identity. To test neighbour recognition, further
playback experiments were performed. Neighbour and stranger
songs were broadcast from the territory boundary shared by the
subject and its adjacent neighbour whose song was played back,
and from the opposite boundary. Subjects exhibit a lower
aggression towards neighbour songs at the shared boundary but
display the same level of aggression to the two categories of
songs at the opposite one. Thus, males showed a spatial
categorisation of their proximate neighbours. Acoustic analyses
revealed that individual information is potentially carried by the
syllable organisation. Thus, the syntax may code for distinct
messages and different identities.
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Effects of fish size on agonistic sounds in the clownfish
Amphiprion akallopisos: implications for the role of the
swimbladder in the sound production mechanism.
Orphal Colleye 1 , Pierre Vandewalle 1 , Bruno Frédérich 1 , Margarida
Casadevall 2 and Eric Parmentier 1
1 Laboratoire de Morphologie Fonctionnelle et Evolutive,
Département des Sciences et Gestion de l’Environnement,
Université de Liège, Institut de Chimie, Bât B6c, 4000 Liège,
Belgium
2 Unitat de Biologia Animal, Facultat de Ciències, Universitat de
Girona, Campus de Montilivi s/n, 17071 Girona, Spain
Clownfishes (i.e. Amphiprion akallopisos) are territorial fishes that
use sound production to defend their anemone territory. In this
context, agonistic interactions are frequent and are often
associated with sounds that are called “pops”. In sonic fishes, the
swimbladder is often involved in sound production, mainly acting
as resonance chamber. Currently, the potential role of the
swimbladder in sound production has not been demonstrated yet
in clownfishes.
In the present study, we thus compared the sonic features
between individuals of different sizes and in different sexual status
(juvenile, male and female). The role of the swimbladder in sound
production was also tested using an experimental filling with
physiological liquid.
In A. akallopisos, fish size is highly correlated with swimbladder
size. Sound analyses showed that dominant frequency and pulse
duration are highly related to fish size (r² = 0.95). No variations in
sounds are related to sex. The experimental filling of the
swimbladder with physiological liquid significantly modified the
acoustic features.
In A. akallopisos, frequency and pulse duration are directly related
to fish size, and thus to swimbladder size. This study highlights the
role of the swimbladder in the sound production mechanism in
clownfishes, acting as a resonance chamber.
Vocal competition between two hybridizing seabird species
Charlotte Curé 1,2 , Nicolas Mathevon 1,2 and Thierry Aubin 1
1 Equipe ‘Communications acoustiques’, Laboratoire Neurobiologie,
de l’Apprentissage, de la Mémoire et de la Communication UMR
CNRS 8620, Université Paris-Sud, F-91405 Orsay cedex, France.
2 Laboratoire d’Ecologie et Neuro-Ethologie Sensorielles EA3988,
Université Jean Monnet, F-42023 Saint-Etienne cedex 2, France.
Whereas the impact of sexual selection on the evolution of vocal
signals has been extensively studied in song-learning birds, it has
been so far largely neglected in non song-birds, especially the
intra-sex component of sexual selection. Using the opportunity
offered by shearwaters where mates take turns to incubate and
specifically interact with same-sex individuals during nest defence,
we investigated the relationship between intra-sex vocal
interactions and hybridization in two allopatric closely related
species, the Yelkouan and the Balearic shearwaters (Puffinus
yelkouan and P. mauretanicus). Acoustic analysis of the territorial
call recorded in the allopatric populations of each species revealed
that this call carries both reliable sex- and species-specific
signatures. Calls of hybrid birds showed an intermediate structure
to those of parental species, underlining the genetic basis of
vocalization structure. While birds from the hybridization zone and
from the Yelkouan population responded equally to playback of
both parental vocalizations, the Balearic reacted less strongly to
heterospecific calls than to conspecific calls. This asymmetry
between both parental species in intra-sex competition may have
important fitness consequences, in that Yelkouan individuals are
more likely to introgress into Balearic populations than the reverse.
Moreover, as Balearic males less readily respond during intra-sex
interaction with Yelkouan individuals than females do, Yelkouan
introgression into the Balearic population may be primarily driven
by males.