The Experts below are selected from a list of 2181 Experts worldwide ranked by ideXlab platform
Marc Naguib - One of the best experts on this subject based on the ideXlab platform.
-
Ibis
2016Co-Authors: Marc Naguib, Hansjoerg P Kunc, Rouven Schmidt, Valentin AmrheinAbstract:Temporal patterns of territory settlement and detectability in mated and unmated Nightingales Luscinia megarhyncho
-
investigation of musicality in birdsong
Hearing Research, 2014Co-Authors: David Rothenberg, Marc Naguib, Tina C Roeske, Henning U Voss, Ofer TchernichovskiAbstract:Songbirds spend much of their time learning, producing, and listening to complex vocal sequences we call songs. Songs are learned via cultural transmission, and singing, usually by males, has a strong impact on the behavioral state of the listeners, often promoting affiliation, pair bonding, or aggression. What is it in the acoustic structure of birdsong that makes it such a potent stimulus? We suggest that birdsong potency might be driven by principles similar to those that make music so effective in inducing emotional responses in humans: a combination of rhythms and pitches-and the transitions between acoustic states-affecting emotions through creating expectations, anticipations, tension, tension release, or surprise. Here we propose a framework for investigating how birdsong, like human music, employs the above "musical" features to affect the emotions of avian listeners. First we analyze songs of thrush nightingales (Luscinia Luscinia) by examining their trajectories in terms of transitions in rhythm and pitch. These transitions show gradual escalations and graceful modifications, which are comparable to some aspects of human musicality. We then explore the feasibility of stripping such putative musical features from the songs and testing how this might affect patterns of auditory responses, focusing on fMRI data in songbirds that demonstrate the feasibility of such approaches. Finally, we explore ideas for investigating whether musical features of birdsong activate avian brains and affect avian behavior in manners comparable to music's effects on humans. In conclusion, we suggest that birdsong research would benefit from current advances in music theory by attempting to identify structures that are designed to elicit listeners' emotions and then testing for such effects experimentally. Birdsong research that takes into account the striking complexity of song structure in light of its more immediate function - to affect behavioral state in listeners - could provide a useful animal model for studying basic principles of music neuroscience in a system that is very accessible for investigation, and where developmental auditory and social experience can be tightly controlled.
-
Song Sharing in Neighboring and Non-Neighboring Thrush Nightingales (Luscinia Luscinia) and its Implications for Communication
Ethology, 2002Co-Authors: Benjamin Grießmann, Marc NaguibAbstract:In many passerines, males have repertoires of different songs of which some songs are often shared with other males. Sharing of song repertoires among males can provide insights into the context in which songs were acquired and on the role of song repertoires in inter- and intrasexual communication. Here we studied repertoire sharing in male territorial thrush nightingales (Luscinia Luscinia). We compared male vocal repertoires of the basic song components, full songs, and the sequencing of songs in a bout. The results show that males differed significantly in the size of their song repertoires but not in the size of the repertoire of basic song components. Moreover, they shared almost all (80%) the repertoire of song components but only 30% of their song types. Neighboring males shared significantly more song types than did non-neighboring males but interestingly they did not share more basic song components than non-neighboring males. These results show that the repertoire of basic song components is under much less sexual selection than the size of song repertoires. Sharing of song repertoires among neighbors presumably results from repertoire conversion over time and from males returning to their territories in the following season. Repertoire sharing then can be an indicator of territory tenure and thus it can be important in repelling rivals and in female choice.
-
Recognition of neighbors' song in a species with large and complex song repertoires : The Thrush Nightingale
Journal of Avian Biology, 1998Co-Authors: Marc Naguib, Dietmar TodtAbstract:To investigate aspects of neighbor recognition in a migratory bird with large and complex song repertoires we conducted playback experiments in the field with male territorial Thrush Nightingales Luscinia Luscinia as subjects. Males sing with immediate variety and neighbors can share a considerable part of their repertoire of song components and song types. Subjects responded significantly more to their neighbors' song broadcast from the unshared (opposite) territorial boundary than to playback of the same song broadcast from the shared territorial boundary. Thus, this study did not detect constraints on neighbor recognition imposed for instance by large and complex song repertoires, high singing versatility, or sharing of song patterns. Because Thrush Nightingales sing shared patterns in different ways, either by constructing different song types out of the shared pool of elements or by singing shared song types in different sequential order, they could attend to song components and their syntactical arrangement, full songs, or their sequential delivery for neighbor recognition. Which mechanism they use might depend on the similarity of the song and singing style of a singer compared to other familiar conspecifics.
-
Vergleich des Strophenaufbaus und der Strophenabfolge an Gesängen von Sprosser (Luscinia Luscinia) und Blaukehlchen (Luscinia svecica)
Journal für Ornithologie, 1992Co-Authors: Marc Naguib, Harald KolbAbstract:Songs of three Thrush Nightingales and three Blue Throats were recorded in the field and analyzed by visual inspection of frequency spectrograms. An analysis of the succession of elements within a song as well as the succession of songs in a song bout revealed the following results in both species: a) the succession of elements within songs was organized as a hierarchical branching structure, b) three structurally different sections could be found in all songs, c) songs were initialized by specific element types. A termination of songs by specific element types was only found in the thrush nightingale. Songs ot the Thrush Nightingale were organized as series of songs which corresponded in their first two element types (same song class). These series consisted of different song types, which succeeded with a high constancy. Different song types were sung in close sequential association and recurred preferably after intervals of 8–10 songs. In song bouts of the Blue Throat however songs which corresponded in all sections were rarely found. Those songs corresponding in the first two element types were often repeated immediately, but in comparison to the Thrush Nightingale series of these songs were rare. Besides many similarities in the song organization in both species the song of the Thrush Nightingale was more similar to the closely related Nightingale ( Luscinia megarhynchos ) — with regard to the syntactical organization of song and the organization of consecutive songs. The song organization of the Blue Throat showed more similarities to the European Redstart ( Phoenicurus phoenicurus ). These results indicate a relation between the syntactical organization of song and the sequential organisation of consecutive songs. Ziel der Studie war es, die Elementabfolge sowie die Strophenabfolge des Gesanges von Sprosser und Blaukehlchen vergleichend zu untersuchen. Zur sonagraphischen Analyse wurden die Gesänge im Freiland aufgezeichnet. Der Abfolge (Syntax) der Strophenelemente lag bei beiden Arten ein hierarchisch organisiertes Verzweigungsschema zu Grunde. Bei beiden Arten konnten die Strophen anhand definierter Strukturparameter klar in drei Abschnitte gegliedert werden. Die Gesänge der Sprosser wurden von Serien aus Strophen gebildet, die jeweils in ihren beiden Anfangselementtypen übereinstimmten (gleiche Strophenklasse). Die Abfolge von Strophen verschiedenen Typs war durch bevorzugte Übergänge und ein gruppiertes Auftreten bestimmter Strophentypen charakterisiert. Beim Blaukehlchen traten Strophen, die in allen Abschnitten strukturell gleich waren, seltener im Gesang wieder auf. Die Blaukehlchen wechselten häufiger die Strophenklasse, wodurch es nur seltener zu einer Serienbildung von gleichklassigen Strophen kam. Die auffälligen Gemeinsamkeiten in der Gesangsorganisation zwischen Sprosser und Nachtigall sowie Blaukehlchen und Gartenrotschwanz liefern Hinweise auf Zusammenhänge zwischen der syntaktischen Organisation von Strophen und der Organisation der Strophenabfolge.
Åke Lindström - One of the best experts on this subject based on the ideXlab platform.
-
fuel deposition and speed of early autumn migration of juvenile bluethroats Luscinia s svecica leaving their natal area in swedish lapland
Ornis Svecica; 11(4) pp 253-263 (2001), 2001Co-Authors: Åke Lindström, Johan LindAbstract:Fuel deposition and speed of early autumn migration of juvenile bluethroats Luscinia s. svecica leaving their natal area in Swedish Lapland
-
Variation in energy intake and basal metabolic rate of a bird migrating in a wind tunnel
Functional Ecology, 1999Co-Authors: Åke Lindström, Marcel Klaassen, Anders KvistAbstract:1. We studied the changes in body mass, metabolizable energy intake rate (ME) and basal metabolic rate (BMR) of a Thrush Nightingale, Luscinia Luscinia, following repeated 12-h migratory flights in a wind tunnel. In total the bird flew for 176 h corresponding to 6300 km. This is the first study where the fuelling phase has been investigated in a bird migrating in captivity. 2. ME was Very high, supporting earlier findings that migrating birds have among the highest intake rates known among homeotherms. ME was significantly higher the second day of fuelling, indicating a build-up of the capacity of the digestive tract during the first day of fuelling. 3. Further indications of an increase in size or activity level of metabolically active structures during fuelling come from the short-term variation in BMR, which increased over the 2-day fuelling period with more than 20%, and in almost: direct proportion to body mass. However, mass-specific BMR decreased over the season. 4. The patterns of mass change, ME and BMR of our focal bird following two occasions of 12-h fasts were the same as after flights, indicating that fast and flight may involve similar physiological processes. 5. The relatively low ME the first day following a flight may be a contributing factor to the well-known pattern that migrating birds during stopover normally lose mass the first day of fuelling. [KEYWORDS: body mass increase; intra-individual variation; Luscinia Luscinia; stopover ecology; Thrush Nightingale Distance migrant shorebird; calidris-canutus; body-composition; garden warbler; sylvia borin; fat deposition; mass; size; allometry; stopover]
-
COMPOSITION OF FUEL STORES AND DIGESTIVE LIMITATIONS TO FUEL DEPOSITION RATE IN THE LONG-DISTANCE MIGRATORY THRUSH NIGHTINGALE, Luscinia Luscinia
Physiological zoology, 1997Co-Authors: Marcel Klaassen, Åke Lindström, Richtje ZijlstraAbstract:During their autumn migratory phase, thrush nightingales (Luscinia Luscinia) previously starved for 2 d were allowed to refuel under three different ambient temperature conditions (-7 degrees, 7 degrees, and 22 degrees C). During the refueling period, as well as during the preceding control and starvation periods, food intake, body mass, and feces production were monitored. In addition, daily energy expenditure was measured during the refueling period. The compilation of the energy balance during the refueling period revealed an energy density of the deposited tissue of 33.6 kJ g-1. Assuming that the deposited tissue consists of fat and protein exclusively, with energy densities of 39.6 and 5.5 kJ g-1 wet mass, respectively, we estimated the deposited tissue to consist of 82% fat and 18% wet protein (6% dry protein and 12% water). Nitrogen balances during control, starvation, and refueling phases and during a period of prolonged and complete starvation indicated that 5% of the nutrient stores consisted of dry protein. Our results support recent findings that nutrient stores for migration often contain protein in addition to fat and consequently are 15%-25% less energy rich than pure fat stores. These proteins might be stored as muscle or other functional tissue and may be required to support the extra mass of the stores and/or reflect an incapacity of the metabolic machinery to catabolize far exclusively. Fuel deposition rate was positively related with ambient temperature, whereas food intake rate was unaffected by temperature. These results indicate that the rate of fuel deposition is limited by a ceiling in food intake rate; when this ceiling is reached, fuel deposition rate is negatively affected by daily energy expenditure rate. To a certain extent, the ceiling in food intake rate varies depending on feeding conditions over the previous days. These variations in food intake capacity probably reflect the building and breakdown of gut tissues and/or gut enzyme systems and might be insensible and not evolutionary adaptive. Significant energetic costs, however, are probably associated with the maintenance of gut tissues. It is therefore feasible that changes in digestive capacity are regulated and are directed at energy economization.
-
Wingbeat frequency and the body drag anomaly: wind-tunnel observations on a thrush nightingale (Luscinia Luscinia) and a teal (Anas crecca)
The Journal of Experimental Biology, 1996Co-Authors: C. J. Pennycuick, Anders Kvist, Marcel Klaassen, Åke LindströmAbstract:A teal (Anas crecca) and a thrush nightingale (Luscinia Luscinia) were trained to fly in the Lund wind tunnel for periods of up to 3 and 16 h respectively. Both birds flew in steady flapping flight, with such regularity that their wingbeat frequencies could be determined by viewing them through a shutter stroboscope. When flying at a constant air speed, the teal's wingbeat frequency varied with the 0.364 power of the body mass and the thrush nightingale's varied with the 0.430 power. Both exponents differed from zero, but neither differed from the predicted value (0.5) at the 1 % level of significance. The teal continued to flap steadily as the tunnel tilt angle was varied from -1 ° (climb) to +6 ° (descent), while the wingbeat frequency declined progressively by about 11 %. In both birds, the plot of wingbeat frequency against air speed in level flight was U-shaped, with small but statistically significant curvature. We identified the minima of these curves with the minimum power speed (Vmp) and found that the values predicted for Vmp, using previously published default values for the required variables, were only about two-thirds of the observed minimum-frequency speeds. The discrepancy could be resolved if the body drag coefficients (CDb) of both birds were near 0.08, rather than near 0.40 as previously assumed. The previously published high values for body drag coefficients were derived from wind-tunnel measurements on frozen bird bodies, from which the wings had been removed, and had long been regarded as anomalous, as values below 0.01 are given in the engineering literature for streamlined bodies. We suggest that birds of any size that have well-streamlined bodies can achieve minimum body drag coefficients of around 0.05 if the feet can be fully retracted under the flank feathers. In such birds, field observations of flight speeds may need to be reinterpreted in the light of higher estimates of Vmp. Estimates of the effective lift:drag ratio and range can also be revised upwards. Birds that have large feet or trailing legs may have higher body drag coefficients. The original estimates of around CDb=0.4 could be correct for species, such as pelicans and large herons, that also have prominent heads. We see no evidence for any progressive reduction of body drag coefficient in the Reynolds number range covered by our experiments, that is 21 600215 000 on the basis of body cross-sectional diameter.
Marie-christine Eybert - One of the best experts on this subject based on the ideXlab platform.
-
deplacements inattendus chez des mâles de gorgebleue a miroir blanc Luscinia svecica namnetum en periode de nidification unexpected movements of male bluethroats Luscinia svecica namnetum during the breeding period
Alauda, 2016Co-Authors: Clément Harmange, Matthieu Marquet, Julie Dietrich, Sarah Monnet, Elisa Gregoire, Marie-christine Eybert, Laurent Godet, Jerome FournierAbstract:Unexpected movements of male Bluethroats Luscinia svecica namnetum during the breeding period. During a radiotracking survey on 61 different males of Bluethroat Luscinia svecica namnetum from 2012 to 2015 in three different sites, we found that 8 males joined remote areas, at 300 to 900 meters from their regular territory and home range. These movements occurred at dawn and dusk, but also at day. Such movements are not recorded in the literature and we propose four different hypotheses to explain them: the existence of extra-pair copulation places, a male poly-territoriality, the look for food or for a shelter from predators.
-
Bluethroats Luscinia svecica namnetum offset landscape constraints by expanding their home range
Journal of Ornithology, 2015Co-Authors: Laurent Godet, Matthieu Marquet, Sarah Monnet, Elisa Gregoire, Marie-christine Eybert, Jerome FournierAbstract:The highly fragmented landscape structures of coastal salinas are known to result in decreased terrestrial bird abundance, species richness and diversity but to promote original assemblages dominated by specialist species, such as the Bluethroat Luscinia svecica namnetum . This species is mainly found at the core of these salinas, where the landscape characteristics are a priori the most hostile for terrestrial birds. The aim of this study was to test whether individuals of a specialized species like the Bluethroat may offset such landscape constraints by expanding their home ranges. We therefore radio-tracked 21 males in 2013 and 2014 in the salinas of the Marais du Mès (Parc Naturel Régional de Brière, Western France). The data of the 18 best-monitored males were used to carry out a hierarchical partitioning of variance to test the relative influence of landscape characteristics, individual characteristics and distance to other males on their home-range sizes. We found that landscape characteristics were the factors that best explained home range sizes. Home-range sizes were significantly smaller in diversified landscapes composed of tidal creeks and salt-marsh patches and tended to be larger in landscapes dominated by the aquatic matrix consisting of water ponds. The results of this study demonstrate that although a few bird species are able to select a priori hostile landscapes, they can offset such constraints by expanding their home-range size. Blaukehlchen Luscinia svecica namnetum gleichen Einschränkungen im Lebensraum mit einer Erweiterung ihres Aktionsraumes aus Es ist bekannt, dass die stark fragmentierten Landschaftsstrukturen von küstennahen Salzmarschen Häufigkeit, Artenreichtum und Vielfalt von terrestrischen Vögeln verringert, aber Gemeinschaften begünstigen, die von Spezialisten wie dem Blaukehlchen Luscinia svecica namnetum dominiert werden. Diese Art ist daher hauptsächlich im Zentrum von Salzmarschen zu finden, wo die Landschaftsstrukturen für terrestrische Vögel am widrigsten sind. Ziel dieser Studie war es zu testen, ob Individuen dieser Art die Einschränkungen ihres Lebensraumes durch eine Erweiterung ihres Aktionsraumes ausgleichen. 21 Männchen wurden in 2013 und 2014 in den Salzmarschen des Marais du Mès (Parc Naturel Régional de Brière, Westfrankreich) radio-telemetriert. Die Daten der 18 best-verfolgten Individuen wurden genutzt um in einer hierarchischen Teilung der Varianz den relativen Einfluss von (i) Landschaftsstruktur (ii) Individuellen Unterschieden, sowie (iii) Abstand zu andern Männchen, auf die Größe ihres Aktionsraums. Landschaftsstruktur war dabei der Faktor, der die Größe des Aktionsraumes am besten erklärte. Aktionsräume waren signifikant kleiner in vielfältigeren Lebensräumen mit Prielen und Salzwiesen und größer in Lebensräumen mit einer aquatischen Grundsubstanz bestehend aus Teichen. Diese Studie zeigt, dass obwohl nur wenige Vogelarten fähig sind in grundsätzlich widrigen Lebensräumen zu siedeln, jene Arten die Einschränkungen durch eine Ausweitung ihres Aktionsraumes wieder ausgleichen können.
-
Rapid sperm evolution in the bluethroat (Luscinia svecica) subspecies complex
Behavioral Ecology and Sociobiology, 2013Co-Authors: Silje Hogner, Marie-christine Eybert, Václav Pavel, Bohumír Chutný, Ekaterina Matsyna, Javier Garcia, Terje Laskemoen, Jan T. Lifjeld, Arild JohnsenAbstract:Spermatozoa are among the most variable animal cell types, and much research is currently directed towards explaining inter- and intraspecific variation in sperm form and function. Recent comparative studies in passerine birds have found associations between the level of sperm competition and both sperm length and sperm velocity. In species with sperm competition, postcopulatory sexual selection may shape the morphology of sperm as adaptations to the female environment. The speed of evolutionary change in sperm morphology at the species level is largely unknown. In this study, we analysed variation in sperm morphology among morphologically distinct and geographically isolated bluethroat subspecies in Europe. Consistent with previous studies, our analyses of mtDNA and nuclear introns suggest recent divergence and lack of lineage sorting among the subspecies. We found significant divergence in total sperm length and in the length of some sperm components (i.e. head and midpiece). There was a significantly positive relationship between pairwise divergences in sperm morphology and mitochondrial DNA, suggesting a role for genetic drift in sperm divergence. The magnitude of sperm length divergence was considerably higher than that in other geographically structured passerines, and even higher than that observed between several pairs of sister species. We hypothesize that the rapid sperm evolution in bluethroats is driven by sperm competition, and that strong postcopulatory sexual selection on sperm traits can lead to rapid speciation through reproductive incompatibilities.
-
age related improvement of reproductive success in bluethroats Luscinia svecica
Bird Study, 2004Co-Authors: Thomas Geslin, Sophie Questiau, Marie-christine EybertAbstract:Capsule Young birds are less likely to have high reproductive success compared with older ones because of a lack of several skills influencing breeding performance. Aims To test the ‘constraint’ hypothesis by investigating the effect of male and female age on reproductive performance of a Bluethroat Luscinia svecica population. Methods We compared two age-classes (yearling versus old), breeding for the first time at Guerande salt-pans, France, by evaluating arrival dates on breeding site, territory quality, laying dates, clutch size and egg size, delay before re-nesting, breeding performance, feeding rate at two different nestling periods (on days 4–5 and 10–11 after hatching) and nestling body condition. Results Our results clearly demonstrated an age effect on reproductive performance for both males and females: young breeders were less likely to fledge young. In older males, improvement of reproductive success was related to feeding rate during the first nestling period. For females, timing of breeding...
-
3622 influence de la distance entre les nids de couvees successives sur le succes de la nichee chez la gorgebleue a miroir Luscinia svecica namnetum
Alauda, 2003Co-Authors: Thomas Geslin, Marie-christine EybertAbstract:The exceptional record of clutches in the same nest raises the question of the influence of the distances between successive clutches on the nest success of the second clutch. In Bluethroat Luscinia svecica, the more the second nest was distant from the first, the better was its success.
Harald Kolb - One of the best experts on this subject based on the ideXlab platform.
-
Vergleich des Strophenaufbaus und der Strophenabfolge an Gesängen von Sprosser (Luscinia Luscinia) und Blaukehlchen (Luscinia svecica)
Journal für Ornithologie, 1992Co-Authors: Marc Naguib, Harald KolbAbstract:Songs of three Thrush Nightingales and three Blue Throats were recorded in the field and analyzed by visual inspection of frequency spectrograms. An analysis of the succession of elements within a song as well as the succession of songs in a song bout revealed the following results in both species: a) the succession of elements within songs was organized as a hierarchical branching structure, b) three structurally different sections could be found in all songs, c) songs were initialized by specific element types. A termination of songs by specific element types was only found in the thrush nightingale. Songs ot the Thrush Nightingale were organized as series of songs which corresponded in their first two element types (same song class). These series consisted of different song types, which succeeded with a high constancy. Different song types were sung in close sequential association and recurred preferably after intervals of 8–10 songs. In song bouts of the Blue Throat however songs which corresponded in all sections were rarely found. Those songs corresponding in the first two element types were often repeated immediately, but in comparison to the Thrush Nightingale series of these songs were rare. Besides many similarities in the song organization in both species the song of the Thrush Nightingale was more similar to the closely related Nightingale ( Luscinia megarhynchos ) — with regard to the syntactical organization of song and the organization of consecutive songs. The song organization of the Blue Throat showed more similarities to the European Redstart ( Phoenicurus phoenicurus ). These results indicate a relation between the syntactical organization of song and the sequential organisation of consecutive songs. Ziel der Studie war es, die Elementabfolge sowie die Strophenabfolge des Gesanges von Sprosser und Blaukehlchen vergleichend zu untersuchen. Zur sonagraphischen Analyse wurden die Gesänge im Freiland aufgezeichnet. Der Abfolge (Syntax) der Strophenelemente lag bei beiden Arten ein hierarchisch organisiertes Verzweigungsschema zu Grunde. Bei beiden Arten konnten die Strophen anhand definierter Strukturparameter klar in drei Abschnitte gegliedert werden. Die Gesänge der Sprosser wurden von Serien aus Strophen gebildet, die jeweils in ihren beiden Anfangselementtypen übereinstimmten (gleiche Strophenklasse). Die Abfolge von Strophen verschiedenen Typs war durch bevorzugte Übergänge und ein gruppiertes Auftreten bestimmter Strophentypen charakterisiert. Beim Blaukehlchen traten Strophen, die in allen Abschnitten strukturell gleich waren, seltener im Gesang wieder auf. Die Blaukehlchen wechselten häufiger die Strophenklasse, wodurch es nur seltener zu einer Serienbildung von gleichklassigen Strophen kam. Die auffälligen Gemeinsamkeiten in der Gesangsorganisation zwischen Sprosser und Nachtigall sowie Blaukehlchen und Gartenrotschwanz liefern Hinweise auf Zusammenhänge zwischen der syntaktischen Organisation von Strophen und der Organisation der Strophenabfolge.
-
vergleich des strophenaufbaus und der strophenabfolge an gesangen von sprosser Luscinia Luscinia und blaukehlchen Luscinia svecica
Journal of Ornithology, 1992Co-Authors: Marc Naguib, Harald KolbAbstract:Ziel der Studie war es, die Elementabfolge sowie die Strophenabfolge des Gesanges von Sprosser und Blaukehlchen vergleichend zu untersuchen. Zur sonagraphischen Analyse wurden die Gesange im Freiland aufgezeichnet. Der Abfolge (Syntax) der Strophenelemente lag bei beiden Arten ein hierarchisch organisiertes Verzweigungsschema zu Grunde. Bei beiden Arten konnten die Strophen anhand definierter Strukturparameter klar in drei Abschnitte gegliedert werden. Die Gesange der Sprosser wurden von Serien aus Strophen gebildet, die jeweils in ihren beiden Anfangselementtypen ubereinstimmten (gleiche Strophenklasse). Die Abfolge von Strophen verschiedenen Typs war durch bevorzugte Ubergange und ein gruppiertes Auftreten bestimmter Strophentypen charakterisiert. Beim Blaukehlchen traten Strophen, die in allen Abschnitten strukturell gleich waren, seltener im Gesang wieder auf. Die Blaukehlchen wechselten haufiger die Strophenklasse, wodurch es nur seltener zu einer Serienbildung von gleichklassigen Strophen kam. Die auffalligen Gemeinsamkeiten in der Gesangsorganisation zwischen Sprosser und Nachtigall sowie Blaukehlchen und Gartenrotschwanz liefern Hinweise auf Zusammenhange zwischen der syntaktischen Organisation von Strophen und der Organisation der Strophenabfolge.
Radka Reifova - One of the best experts on this subject based on the ideXlab platform.
-
Tracing the early steps of competition-driven eco-morphological divergence in two sister species of passerines
Evolutionary Ecology, 2020Co-Authors: Camille Sottas, Jiři Reif, Jakub Kreisinger, Lucie Schmiedová, Tomasz S. Osiejuk, Radka ReifovaAbstract:Competition-driven feeding niche separation is assumed to be an important driver of the morphological divergence of co-occurring animal species. However, despite a strong theoretical background, empirical studies showing a direct link between competition, diet divergence and specific morphological adaptations are still scarce. Here we studied the early steps of competition-driven eco-morphological divergence in two closely related passerines: the common nightingale ( Luscinia megarhynchos ) and the thrush nightingale ( Luscinia Luscinia ). Our aim was to test whether previously-observed divergence in bill morphology and habitat in sympatric populations of both species is associated with dietary niche divergence. We collected and analysed data on (1) diet, using both DNA metabarcoding and visual identification of prey items, (2) habitat use, and (3) bill morphology in sympatric populations of both nightingale species. We tested whether the species differ in diet composition and whether there are any associations among diet, bill morphology and habitat use. We found that the two nightingale species have partitioned their feeding niches, and showed that differences in diet may be partially associated with the divergence in bill length in sympatric populations. We also observed an association between bill length and habitat use, suggesting that competition-driven habitat segregation could be linked with dietary and bill size divergence. Our results suggest that interspecific competition is an important driver of species’ eco-morphological divergence after their secondary contact, and provide insight into the early steps of such divergence in two closely related passerine species. Such divergence may facilitate species coexistence and strengthen reproductive isolation between species, and thus help to complete the speciation process.
-
Sperm divergence in a passerine contact zone: Indication of reinforcement at the gametic level
Evolution; international journal of organic evolution, 2019Co-Authors: Tomáš Albrecht, Arild Johnsen, Jiri Reif, Václav Janoušek, Kamila Opletalová, Lubomír Piálek, Emily R. A. Cramer, Radka ReifovaAbstract:Postcopulatory sexual selection may promote evolutionary diversification in sperm form, but the contribution of between-species divergence in sperm morphology to the origin of reproductive isolation and speciation remains little understood. To assess the possible role of sperm diversification in reproductive isolation, we studied sperm morphology in two closely related bird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia Luscinia), that hybridize in a secondary contact zone spanning Central and Eastern Europe. We found: (1) striking divergence between the species in total sperm length, accompanied by a difference in the length of the mitochondrial sperm component; (2) greater divergence between species in sperm morphology in sympatry than in allopatry, with evidence for character displacement in sperm head length detected in L. megarhynchos; (3) interspecific hybrids showing sperm with a length intermediate between the parental species, but no evidence for decreased sperm quality (the proportion of abnormal spermatozoa in ejaculates). Our results demonstrate that divergence in sperm morphology between the two nightingale species does not result in intrinsic postzygotic isolation, but may contribute to postcopulatory prezygotic isolation. This isolation could be strengthened in sympatry by reinforcement.
-
Postcopulatory sexual selection reduces Z-linked genetic variation and might contribute to the large Z effect in passerine birds.
Heredity, 2018Co-Authors: Václav Janoušek, Jiři Reif, Marcin Antczak, Jitka Fischerová, Libor Mořkovský, Tomáš Albrecht, Radka ReifovaAbstract:The X and Z sex chromosomes play a disproportionately large role in intrinsic postzygotic isolation. The underlying mechanisms of this large X/Z effect are, however, still poorly understood. Here we tested whether faster rates of molecular evolution caused by more intense positive selection or genetic drift on the Z chromosome could contribute to the large Z effect in two closely related passerine birds, the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (L. Luscinia). We found that the two species differ in patterns of molecular evolution on the Z chromosome. The Z chromosome of L. megarhynchos showed lower levels of within-species polymorphism and an excess of non-synonymous polymorphisms relative to non-synonymous substitutions. This is consistent with increased levels of genetic drift on this chromosome and may be attributed to more intense postcopulatory sexual selection acting on L. megarhynchos males as was indicated by significantly longer sperm and higher between-male variation in sperm length in L. megarhynchos compared to L. Luscinia. Interestingly, analysis of interspecific gene flow on the Z chromosome revealed relatively lower levels of introgression from L. megarhynchos to L. Luscinia than vice versa, indicating that the Z chromosome of L. megarhynchos accumulated more hybrid incompatibilities. Our results are consistent with the view that postcopulatory sexual selection may reduce the effective population size of the Z chromosome and thus lead to stronger genetic drift on this chromosome in birds. This can result in relatively faster accumulation of hybrid incompatibilities on the Z and thus contribute to the large Z effect.
-
Sottas_et_al_JEB_Data.xlsx
2018Co-Authors: Camille Sottas, Jiri Reif, Lechoslaw Kuczynski, Radka ReifovaAbstract:A XLSX spreadsheet containing data on morphology and habitat of Common Nightingale (Luscinia megarhynchos) and Thrush Nightingale (Luscinia Luscinia) in the sympatric zone
-
Data file including information about experiments
2018Co-Authors: Abel Souriau, Radka Reifova, Jana Vokurkova, Adam Petrusek, Jiri Reif, Hana Kohoutová, Tereza PetruskovaAbstract:A XLS spreadsheet containing information on individual experiments testing responses of Common Nightingale (Luscinia megarhynchos) males in a contact zone with the Thrush Nightingale (Luscinia Luscinia) to playback of three types of stimuli: pure conspecific song (LM), pure heterospecific song (LL), and mixed heterospecific song (mix)
