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See detailTriclosan retardes development of Sheepshead minnow (Cyprinodon variegatus)
Dussenne, Mélanie ULg; Frederich, Bruno ULg; Das, Krishna ULg et al

Conference (2015, October)

The aquatic environment represents the final sink for many chemicals, including bactericidal agents. Among them Triclosan (TCS), with his chemical structure similar to thyroid hormones (THs), may have ... [more ▼]

The aquatic environment represents the final sink for many chemicals, including bactericidal agents. Among them Triclosan (TCS), with his chemical structure similar to thyroid hormones (THs), may have adverse effects on the thyroid system. The study we carried out aims to evaluate the effects of TCS exposure on development of Cyprinodon variegatus, a fish model used in ecotoxicological studies. We investigated the potential effects of TCS on C. variegatus during two key periods; embryonic development and metamorphosis. We exposed eggs and larvae to environmental relevant concentrations. We showed that TCS had no effect on reproduction parameters, such as egg fertility or survival rate of larvae. However, we highlighted the fact that hatching of exposed larvae was delayed of around 6 to 13 hours compared to control embryos. During the larval phase, measurements of THs levels were performed. We showed that TCS affected the typical ontogenic variations of the whole body thyroid hormones concentrations during metamorphosis. As THs are known to control somatic growth and development, we tested the effects of TCS exposure on morphological development. We observed no deformity or malformation, but we revealed a developmental retardation in larvae exposed to TCS, of around 18 to 32 hours. Such a developmental delay had never been highlighted in previous studies on TCS exposed fish. We hypothesize that the disruption of THs homeostasis affects the timing of the start of metamorphosis. As a consequence, exposed larvae showed an extended larval phase compared to the control group. The harmful effects of TCS on physiology and development are a major concern, as marine organisms are constantly exposed to it. Furthermore, strong connections exist between thyroid and reproductive system, which might have deleterious effects on population dynamics. [less ▲]

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See detailImpact of the trophic strategy on the eco-functional diversification of a coral reef fish family
Gajdzik, Laura ULg; Aguilar-Medrano, Rosalia; Parmentier, Eric ULg et al

Conference (2015, September)

The analyses of the role of trophic strategies as promoter or constraint on processes of diversification remain understudied, especially in fish. The Pomacentridae (damselfishes), a species-rich (394 ... [more ▼]

The analyses of the role of trophic strategies as promoter or constraint on processes of diversification remain understudied, especially in fish. The Pomacentridae (damselfishes), a species-rich (394 species) and worldwide distributed reef fish family, include three main trophic guilds: (1) pelagic zooplankton feeders, (2) benthic feeders grazing on turf algae or biting polyps and (3) an intermediate group feeding on zooplankton, small benthic invertebrates and algae. Our study aims to analyze the role of the trophic strategies in the eco-functional diversity of Pomacentridae. Due to its feeding versatility, we hypothesize that the intermediate trophic group is the most successful group in terms of eco-functional diversity through evolutionary time. To target our aim, we compiled detailed dietary, environmental and behavioral data for 201 pomacentrid species, and compared the eco-functional diversity among trophic guilds. Various metrics, such as functional entity (i.e. unique combinations of functional traits) and functional richness revealed that the intermediate trophic group exhibited the lowest diversity. Then, we used time-calibrated phylogenies and comparative methods to evaluate the impact of trophic strategies on the tempo of ecological diversification. Results were consistent and the lowest rate of diversification was found for the intermediate trophic group. Our study shows that a generalist trophic strategy does not promote ecological diversification but being specialized may increase the ability to evolve greater diversity. [less ▲]

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See detailComparison of isotopic turnover dynamics in two different muscles of a coral reef fish during the settlement phase
Gajdzik, Laura ULg; Lepoint, Gilles ULg; Lecchini, David et al

in Scientia Marina (2015), 79(3), 325-333

The temporal variation in carbon and nitrogen isotopic compositions (noted as δ13C and δ15N) was investigated in the convict surgeonfish (Acanthurus triostegus) at Moorea (French Polynesia). Over a period ... [more ▼]

The temporal variation in carbon and nitrogen isotopic compositions (noted as δ13C and δ15N) was investigated in the convict surgeonfish (Acanthurus triostegus) at Moorea (French Polynesia). Over a period of 24 days, juveniles were reared in aquaria and subjected to two different feeding treatments: granules or algae. The dynamics of δ13C and δ15N in two muscles (the adductor mandibulae complex and the epaxial musculature) having different functions were compared. At the end of experiments, a steady-state isotopic system in each muscle tissue was not reached. Especially for the algal treatment, we found different patterns of variation in isotopic compositions over time between the two muscles. The turnovers of δ13C showed opposite trends for each muscle but differences are mitigated by starvation and by the metamorphosis. Our study highlighted that the metabolism of coral reef fish may be subjected to catabolism or anabolism of non-protein precursors at settlement, inducing variation in isotopic compositions that are not linked to diet change. [less ▲]

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See detailThe effects of triclosan exposure in shape changes of sheepshead minnow (Cyprinodon variegatus) during early development and metamorphosis
Schnitzler, Joseph ULg; Frederich, Bruno ULg; Dussenne, Mélanie ULg et al

in Organohalogen Compounds (2015, August)

Thyroid hormones are essential for normal development, and for maintenance of normal physiological functions in vertebrates [1, 2]. In fish, thyroid hormones are involved in the control of osmoregulation ... [more ▼]

Thyroid hormones are essential for normal development, and for maintenance of normal physiological functions in vertebrates [1, 2]. In fish, thyroid hormones are involved in the control of osmoregulation, metabolism, somatic growth and post-hatching metamorphosis [1, 3, 4]. The regulation of thyroid hormone bioavailability in tissues and cells represents a very complex and unique web of feedback systems [2]. In fish and other vertebrates the thyroid cascade involves two components. First, thyroxine (T4) biosynthesis and secretion are largely under central control by the brain–pituitary–thyroid axis [5]. Second, there is the conversion of T4 to its biologically active form 3,5,3-triiodothyronine (T3) and its metabolism and receptor-mediated actions that seems largely to be under peripheral control in extra-thyroidal tissues [6]. The accumulation in the aquatic environment of anthropogenic chemicals, among which are endocrine disrupting chemicals (EDCs) that alter normal hormonal regulation, is having dramatic consequences for humans and wildlife. Numerous chemicals disrupt thyroid homeostasis affecting thyroid hormone (TH) synthesis and transport, and cellular uptake and metabolism [7, 8]. Triclosan (TCS) is a synthetic chlorinated phenolic compound with a generalized use as an antimicrobial and preservative in many personal care and household products [9-11]. As a result of disposal of TCS through sewage systems and insufficient/variable removal by wastewater treatment plants (WWTP) [9], widespread contamination with TCS has been detected in several countries, particularly in aquatic ecosystems, WWTP influents and effluents; sludges and biosolids; surface or ground water; drinking water; and aquatic sediments [9-11]. TCS and its metabolites have been detected in tissues and body fluids of aquatic organisms including fish, revealing they are accumulating in the food chain [9-11] and TCS has also been detected in human blood, breast milk and urine [9-11]. The structural similarity of TCS with THs [9] suggest it may have adverse effects on the thyroid system. However, little is known about the mechanisms by which TCS disrupts the thyroid axis. TCS effects on fish thyroid axis have not been investigated. It is possible, that the TCS toxic effects reported in fish embryos, larvae and adults [9-11] might be caused, at least in part, through its effect on the thyroid system. We determined how TCS affect ontogenic variations of thyroid hormones in developing sheepshead minnow larvae. Knowing that thyroid hormones are involved in somatic growth and post-hatching metamorphosis, we also tested the hypothesis that TCS alter the development of these larvae. To do this, we used landmark-based geometric morphometric methods. These methods allowed us to analyse the pure shape variations of our developing larvae, regardless orientation, position, and size. [less ▲]

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See detailChemical spying in coral reef fish larvae at recruitment
Roux, Natacha; Brooker, Rohan M.; Lecellier, Gaël et al

in Comptes Rendus Biologies (2015), 338

When fish larvae recruit back to a reef, chemical cues are often used to find suitable habitat or to find juvenile or adult conspecifics. We tested if the chemical information used by larvae was ... [more ▼]

When fish larvae recruit back to a reef, chemical cues are often used to find suitable habitat or to find juvenile or adult conspecifics. We tested if the chemical information used by larvae was intentionally produced by juvenile and adult conspecifics already on the reef (communication process) or whether the cues used result from normal biochemical processes with no active involvement by conspecifics (‘‘spying’’ behavior by larvae). Conspecific chemical cues attracted the majority of larvae (four out of the seven species tested); although while some species were equally attracted to cues from adults and juveniles (Chromis viridis, Apogon novemfasciatus), two exhibited greater sensitivity to adult cues (Pomacentrus pavo, Dascyllus aruanus). Our results indicate also that spying cues are those most commonly used by settling fishes (C. viridis, P. pavo, A. novemfasciatus). Only one species (D. aruanus) preferred the odour of conspecifics that had had visual contact with larvae (communication). [less ▲]

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See detailThe evolutionary history of Pomacentridae: key innovation and pattern of diversification
Frederich, Bruno ULg

Scientific conference (2015, April 21)

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See detailUse of C, N and S stable isotope ratios to highlight resource segregation among hermit crabs from tropical seagrass meadows
Michel, Loïc ULg; Frederich, Bruno ULg; Lavitra, Thierry et al

Poster (2015, March 26)

Polyspecific seagrass meadows are ubiquitous features of tropical coastal zones. These ecosystems are of critical ecological importance, and provide a wide range of socio-economical services to local ... [more ▼]

Polyspecific seagrass meadows are ubiquitous features of tropical coastal zones. These ecosystems are of critical ecological importance, and provide a wide range of socio-economical services to local populations. Meadows however undergo multiple threats linked to human activities (increased nutrient input, overfishing, invertebrate overharvesting, etc.). It is currently hard to assess how seagrass meadows could respond to anthropogenic impacts due to poor knowledge of their functional ecology. In an effort to unravel trophic interactions ruling the food webs associated to seagrass beds of the Toliara Great Reef (SW Madagascar), we studied resource segregation between two common Diogenidae hermit crabs (Dardanus scutellatus and Ciliopagurus tricolor) using stable isotope ratios. C, N and S stable isotope ratios of bulk muscle tissue were measured via CF-EA-IRMS (Elementar Vario MicroCube EA coupled to an Isoprime 100 MS). Interspecific differences were noted in isotopic composition of carbon (δ13C = -12.22 ± 1.73 ‰ for D. scutellatus, δ13C = -14.55 ± 0.73 ‰ for C. tricolor), nitrogen (δ15N = 4.73 ± 0.53 ‰ for D. scutellatus, δ15N = 5.20 ± 0.61 ‰ for C. tricolor) and sulfur (δ34S = 14.08 ± 2.32 ‰ for D. scutellatus, δ34S = 16.73 ± 1.49 ‰ for C. tricolor), suggesting that the two species do not feed on the same items. In addition, SIBER (Stable Isotope Bayesian Ellipses in R) modeling based on C and N data clearly showed that no overlap was present in the core isotopic niches of the two species. It also indicated that the isotopic niche of D. scutellatus was greater than the one of C. tricolor, implying that the former feeds on a greater number of items than the latter. While hermit crabs are generally considered as omnivorous species, this study highlighted differences in the foraging ecology of D. scutellatus and C. tricolor. These differences could help to limit competition for food between these two species, and facilitate their coexistence in Malagasy seagrass beds. [less ▲]

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See detailA morphological novelty for feeding and sound production in the yellowtail clownfish
Olivier, Damien ULg; Frederich, Bruno ULg; Herrel, Anthony et al

in Journal of Experimental Zoology. Part A, Comparative Experimental Biology (2015), 323A

The yellowtail clownfish Amphiprion clarkii is able to close its mouth very quickly by means of the cerato-mandibular (c-md) ligament, a synapomorphic trait of Pomacentridae joining the hyoid bar to the ... [more ▼]

The yellowtail clownfish Amphiprion clarkii is able to close its mouth very quickly by means of the cerato-mandibular (c-md) ligament, a synapomorphic trait of Pomacentridae joining the hyoid bar to the medial part of the lower jaw. This fast closure induces tooth collision, thus producing sounds that the clownfish uses during agonistic behaviors. To investigate whether this rapid jaw movement is also used during feeding, we analyzed the kinematics of sound production and feeding. Sound production, feeding on live planktonic prey, and feeding on food attached to tweezers were filmed with a high-speed camera. Three kinds of kinematic patterns were detected and were associated with the two different types of food presented: one performed to catch planktonic prey (PP), and two (called B-1 and B-2) to bite attached food items. The kinematic pattern of B-2 is similar to that observed during sound production (SP) and the transection of the c-md ligament highlights that sound production and biting-2 motions are dependent on this morphological trait. Our data show that the c-md ligament in addition to its role in sound production allows duplication of the mouth closing mechanism during feeding. This highlights the key role played by the c-md ligament in sound production and feeding on attached prey. [less ▲]

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See detailThe cerato-mandibular ligament: an innovation for sound production and feeding in damselfishes (Pomacentridae).
Olivier, Damien ULg; Frederich, Bruno ULg; Spanopoulos-Zarco, Milton et al

Conference (2014, December 12)

The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae ... [more ▼]

The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae possess a synapomorphic trait, the cerato-mandibular (c-md) ligament, which joins the hyoid bar to the inner part of the lower jaw. It has previously been shown that this ligament is a key trait in communication in damselfishes because it enables them to slam the oral jaws shut causing teeth collision and sound production. This specific behavior of mouth closing could, however, also be used for other tasks, such as feeding. Many territorial damselfishes are referred to as farmers, due to their ability to manage algal crops on which they feed. This study hypothesizes that the c-md ligament provides an advantage for grazing filamentous algae, and should thus be considered a key trait for farming behavior. The kinematic patterns associated with sound production and biting filamentous algae or attached animal prey are all based on the same mechanism and are associated with a slam of the oral jaws. We observed that transection of the c-md ligaments makes the fish unable to perform such actions. This study shows that the c-md ligament is a key trait both for sound production and for grazing activities in damselfishes. The buccal jaw slam enables the fish to perform accurate strikes on small filamentous algae. This kind of bite probably plays a major role in farming activity and allows grazing damselfishes to occupy distinct niches, possibly increasing their competitive evolutionary success. [less ▲]

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See detailA morphospace for the marine angelfishes (Pomacanthidae): patterns of diversity
Frederich, Bruno ULg

Poster (2014, December 12)

The Pomacanthidae (marine angelfishes) is an iconic reef fish family of about 88 species. They have a circum-global distribution on tropical to warm-temperate reefs. Marine angelfishes occupy a diverse ... [more ▼]

The Pomacanthidae (marine angelfishes) is an iconic reef fish family of about 88 species. They have a circum-global distribution on tropical to warm-temperate reefs. Marine angelfishes occupy a diverse range of trophic niches, ranging from spongivory and algivory to zooplanktivory. Previous morpho-functional analysis of this family mainly focused on the head region and gut morphology in a limited number of species. However a morphological study including a large sample of angelfish representatives is currently lacking. Here, I explore the diversity of body morphology in this reef fish group. I collected x-ray images of 228 museum specimens from 71 species and I used landmark-based geometric morphometrics to quantify the overall body shape variation within this family. In a test for interspecific allometry, the linear regression of shape variables onto size (LogTL; TL = total length) was significant (P < 0.001). However, the percentage of explained variance in this model (23%) showed no strong relation between size and body shape. Main shape variation across species was explored using a principal component analysis on shape variables. The two main axes (PC1 and PC2) explained 74% of the total variance of the dataset. Pomacanthus spp., which mainly feed on fixed invertebrates (sponges and tunicates), have deep body with high and angular cephalic profile (lowest values along PC1). Conversely, the zooplanktivorous Genicanthus spp., those have a more pelagic lifestyle, show a slender body with shorter anal fin (highest values along PC1). The pigmy angelfishes from the genus Centropyge, which group different diets (omnivory or algivory), show a more robust and rectangular body shape (high scores along PC2). This work provides the row data for future studies dealing with the mode of phenotypic diversification of Pomacanthidae during evolution. [less ▲]

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See detailStable isotope ratios reveal trophic niche partitioning among hermit crabs from tropical polyspecific seagrass meadows
Michel, Loïc ULg; Frederich, Bruno ULg; Lavitra, Thierry et al

Poster (2014, December 12)

Polyspecific seagrass meadows are ubiquitous features of tropical coastal zones. These ecosystems are of critical ecological importance, and provide a wide range of socio-economical services to local ... [more ▼]

Polyspecific seagrass meadows are ubiquitous features of tropical coastal zones. These ecosystems are of critical ecological importance, and provide a wide range of socio-economical services to local populations. Meadows however undergo multiple threats linked to human activities (increased nutrient input, overfishing, invertebrate overharvesting, etc.). It is currently hard to assess how seagrass meadows could respond to anthropogenic impacts due to poor knowledge of their functional ecology. In an effort to unravel trophic interactions ruling the food webs associated to seagrass beds of the Toliara Great Reef (SW Madagascar), we studied resource segregation between two common Diogenidae hermit crabs (Dardanus scutellatus and Ciliopagurus tricolor) using stable isotope ratios. Interspecific differences were noted in isotopic composition of carbon (δ13C = -12.22 ± 1.73 ‰ for D. scutellatus, δ13C = -14.55 ± 0.73 ‰ for C. tricolor), nitrogen (δ15N = 4.73 ± 0.53 ‰ for D. scutellatus, δ15N = 5.20 ± 0.61 ‰ for C. tricolor) and sulfur (δ34S = 14.08 ± 2.32 ‰ for D. scutellatus, δ34S = 16.73 ± 1.49 ‰ for C. tricolor), suggesting that the two species do not feed on the same items. In addition, SIBER (Stable Isotope Bayesian Ellipses in R) modeling based on C and N data clearly showed that no overlap was present in the core isotopic niches of the two species. It also indicated that the isotopic niche of D. scutellatus was greater than the one of C. tricolor, implying that the former feeds on a greater number of items than the latter. While hermit crabs are generally considered as omnivorous species, this study highlighted differences in the foraging ecology of D. scutellatus and C. tricolor. These differences could help to limit competition for food between these two species, and facilitate their coexistence in Malagasy seagrass beds. [less ▲]

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See detailEcological diversity of damselfishes (Pomacentridae) from Moorea
Gajdzik, Laura ULg; Parmentier, Eric ULg; Lepoint, Gilles ULg et al

Poster (2014, December)

The Pomacentridae (damselfishes) represents the 3rd most species-rich coral reef fish family, including 394 species spread worldwide. Recent studies suggested that damselfishes iteratively evolve along ... [more ▼]

The Pomacentridae (damselfishes) represents the 3rd most species-rich coral reef fish family, including 394 species spread worldwide. Recent studies suggested that damselfishes iteratively evolve along three main trophic guilds: “the pelagic feeders” feeding mainly on zooplankton, “the benthic feeders” grazing filamentous algae or biting coral polyps, and an “intermediate” group with species feeding on zooplankton, small benthic invertebrates and algae in variable proportions. Comparing the ecological diversity of damselfish communities among various geographical regions could assess such an iterative radiation. Within this context, the present study is a first attempt exploring the trophic diversity of damselfish community at Moorea Island (French Polynesia). The relationship between the trophic guilds, their habitat diversity and their behavior is evaluated. Habitat and behaviour of 16 damselfish species were described during transects along which different kinds of data were collected. For examples, the location within the reef (e.g. fringing or barrier reef), the depth, the substrate over which fishes are living or the solitary/gregarious habits were recorded. Diet of individuals was investigated by means of stomach content and stable isotopes analyses. Correlations between the dietary preferences and ecological data (habitat and behaviour) are given and the ecological diversity among trophic groups is compared. [less ▲]

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See detailEcomorfologia y evolucion del sistema locomotor de la familia Pomacentridae
Aguilar-Medrano, Rosalia; Frederich, Bruno ULg; Barber, Paul

Conference (2014, November)

Due their productivity, structural diversity, and potential to promote ecological, functional and morphological evolution, coral reefs have the highest species richness of fishes. As swimming is the ... [more ▼]

Due their productivity, structural diversity, and potential to promote ecological, functional and morphological evolution, coral reefs have the highest species richness of fishes. As swimming is the primary form of locomotion and interaction their aquatic environment, small morphological variations can have profound implications on the fitness of fishes. The damselfish family, Pomacentridae, has inhabited coral reef ecosystems for more than 50 million years. As such, habitat preferences and behavior could significantly contribute to the evolution of the morphology of damselfish through the impacts of shape on locomotion. To test this hypothesis, we employed comparative morphometric analyses of fish shape and ecology. While body elongation represented the primary source of variation in locomotor system shape, results also showed a diverse suit of morphological combinations in between the morphological extremes. Results showed strong associations between behavior and habitat preferences, suggesting that behavior may constrain the shape of the locomotor system in damselfishes. Position in the water column show relation with the cephalic region and truck, behavior is related to the cephalic angle and the angle of insertion of the pectoral fin, while maximum depth is related to the caudal peduncle. Was found little relation between the caudal peduncle, the angle of pectoral fin attachment and the rest modules, therefore, this two modules may be the main responsible of swimming fitness in damselfishes. Finally, cephalic region is highly related to most modules, especially to trunk. This strong integration may be responsible of the limit morphological variation of damselfishes. [less ▲]

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See detailThe cerato-mandibular ligament: a key functional trait for grazing in damselfishes (Pomacentridae)
Olivier, Damien ULg; Frederich, Bruno ULg; Spanopoulos-Zarco, Milton et al

in Frontiers in Zoology (2014), 11(63), 1-14

Introduction: The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The ... [more ▼]

Introduction: The success of a taxonomic group can be promoted by a key character that allows the group to interact with its environment in a different way and to potentially occupy new niches. The Pomacentridae possess a synapomorphic trait, the cerato-mandibular (c-md) ligament, which joins the hyoid bar to the inner part of the lower jaw. It has previously been shown that this ligament is a key trait in communication in damselfishes because it enables them to slam the oral jaws shut causing teeth collision and sound production. This specific behavior of mouth closing could, however, also be used for other tasks, such as feeding. Many territorial damselfishes are referred to as farmers, due to their ability to manage algal crops on which they feed. This study hypothesizes that the c-md ligament provides an advantage for grazing filamentous algae, and should thus be considered a key trait for farming behavior. Results: The kinematic patterns associated with sound production and biting filamentous algae or attached animal prey are all based on the same mechanism and are associated with a slam of the oral jaws. We observed that transection of the c-md ligaments makes the fish unable to perform such actions. We also counted biting rates on filamentous algae in fish with and without the c-md ligament and observed a drop of more than 80% in the latter. Conclusion: This study shows that the c-md ligament is a key trait both for sound production and for grazing activities in damselfishes. The buccal jaw slam enables the fish to perform accurate strikes on small filamentous algae. This kind of bite probably plays a major role in farming activity and allows grazing damselfishes to occupy distinct niches, possibly increasing their competitive evolutionary success. [less ▲]

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See detailTrait decoupling promotes evolutionary diversification of the trophic and acoustic system of damselfishes
Frederich, Bruno ULg; Olivier, Damien ULg; Litsios, Glenn et al

in Proceedings of the Royal Society B : Biological Sciences (2014)

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal ... [more ▼]

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal diversity. However, few empirical tests of this hypothesis exist. A central prediction, that the tempo of morphological evolution and ecological diversification should increase following decoupling events, remains inadequately tested. In damselfishes (Pomacentridae), a ceratomandibular ligament links the hyoid bar and lower jaws, coupling two main morphofunctional units directly involved in both feeding and sound production. Here, we test the decoupling hypothesis by examining the evolutionary consequences of the loss of the ceratomandibular ligament in multiple damselfish lineages. As predicted, we find that rates of morphological evolution of trophic structures increased following the loss of the ligament. However, this increase in evolutionary rate is not associated with an increase in trophic breadth, but rather with morphofunctional specialization for the capture of zooplanktonic prey. Lineages lacking the ceratomandibular ligament also shows different acoustic signals (i.e. higher variation of pulse periods) from others, resulting in an increase of the acoustic diversity across the family. Our results support the idea that trait decoupling can increase morphological and behavioral diversity through increased specialization rather than the generation of novel ecotypes. [less ▲]

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See detailDiversification morphologique des poissons récifaux au cours de leur ontogénie et de leur histoire évolutive
Frederich, Bruno ULg

Scientific conference (2014, January 20)

Depuis une dizaine d’années, mes recherches se sont centrées sur la morphologie des poissons des récifs coralliens, et plus particulièrement sur les demoiselles (Pomacentridae). Avec des perspectives ... [more ▼]

Depuis une dizaine d’années, mes recherches se sont centrées sur la morphologie des poissons des récifs coralliens, et plus particulièrement sur les demoiselles (Pomacentridae). Avec des perspectives écologiques et évolutives, j’ai décrit et quantifié les transformations morphologiques subies par différentes espèces de poissons après leur colonisation du récif au moyen de la morphométrie géométrique. Durant mon post-doc actuel, j’étudie le mode et la vitesse de diversification de certaines familles de poissons coralliens au cours de leur histoire évolutive, au moyen de méthodes de phylogénie comparée. [less ▲]

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See detailPattern of morpho-functional diversifcation of damselfishes (Pomacentridae)
Frederich, Bruno ULg

Conference (2013, December 18)

Coral reef fishes represent one of the most outstandingly diverse assemblages of vertebrates on the planet but our understanding of their mode of diversification remains limited. Currently, some ... [more ▼]

Coral reef fishes represent one of the most outstandingly diverse assemblages of vertebrates on the planet but our understanding of their mode of diversification remains limited. Currently, some biologists are testing various hypotheses about the evolutionary history of coral reef fishes and are exploring the factors driving their diversification. During my post-doctoral research, I explored the pattern of morphological diversification of damselfishes (Pomacentridae, 386 species). I produced a time-calibrated phylogeny based on 8 loci including 208 species and collected eco-morphological data (trophic data, body shape and oral jaws shape) in more than 120 species. Using various phylogenetic comparative methods, I have illusrated that the Pomacentridae observed repeated ecological radiation and morphological convergence during their evolutionary history. I have also highlighted the primary role of a ligament joining the mandible and the hyoid in the evolution and the morpho-functional diversification of pomacentrids. [less ▲]

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See detailDiversification of the pectoral fin shape in damselfishes (Perciformes, Pomacentridae) of the Eastern Pacific
Aguilar-Medrano, Rosalia; Frederich, Bruno ULg; Balart, Eduardo F. et al

in Zoomorphology (2013)

Fin shape strongly influences performance of locomotion across all swimming styles. In this study, we focused on the diversity of the pectoral fin morphology in damselfishes of the Eastern Pacific ... [more ▼]

Fin shape strongly influences performance of locomotion across all swimming styles. In this study, we focused on the diversity of the pectoral fin morphology in damselfishes of the Eastern Pacific. Underwater observations and a review of literature allowed the characterization of ten behavioral groups. Territorial and non-territorial species were discriminated easily with traditional morphometrics. Five ecomorphological groups were recognized by geometric morphometric analyses. Geometric data segregated the outgroup from the damselfishes and allowed the distinction of mean morphologies from extreme ones within territorial and non-territorial species. Additionally, geometric morphometric data split Abudefduf into two groups: (1) A. troschelii is similar to C. atrilobata and (2) A. concolor and A. declivifrons are close to Stegastes. Solitary territorial species (e.g., Stegastes) show rounded and high fins whereas non-territorial species living in groups (e.g., Chromis) present long and curved pectoral fins. In the range of morphological variation, the morphologies of Microspathodon (elongate with highly curved hydrodynamic trailing edge) and Azurina (long, slender and angular) represent the extreme morphologies within territorial and non-territorial species, respectively. Our study revealed a strong relationship between the pectoral fin shape and the behavioral diversification in damselfishes. [less ▲]

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