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Philip L Munday - One of the best experts on this subject based on the ideXlab platform.
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Coral colony size and structure as determinants of habitat use and fitness of coral-dwelling fishes
Marine Ecology Progress Series, 2016Co-Authors: Pedro Henrique Cipresso Pereira, Philip L MundayAbstract:Competition for space affects patterns of habitat use and individual performance of coral-dwelling fishes; however, the physical attributes of corals that influence habitat preferences are uncertain. In this study, we investigated the influence of coral colony size and branching structure of 2 coral species, Acropora nasuta and Acropora spathulata, on habitat use and growth rate of 2 coral gobies, Gobiodon histrio and G. erythrospilus. First, we examined 2 key aspects of coral colony structure (interbranch depth and interbranch width) that may influence habitat preferences. We then used laboratory and field-based experiments to test the effects of coral species, coral colony size and branching structure on habitat preference and growth rates of G. histrio and G. erythrospilus. The preferred coral species, A. nasuta, had smaller interbranch width than A. spathulata. A binary-choice laboratory experiment demonstrated that both goby species preferred coral colonies with smaller interbranch width, except when they had the opportunity to occupy A. nasuta over A. spathulata. A field transplant experiment showed that both goby species grew faster on larger coral colonies and in colonies with smaller interbranch width. G. erythrospilus grew faster than G. histrio on A. spathulata, indicating that it suffers less fitness loss when occupying this alternative habitat. Our results show that coral physical attributes are important factors driving habitat preference of coral-dwelling gobies; however, there must also be additional factors that influence their habitat use. Declining average coral size and reduced habitat complexity on coral reefs could have significant impacts on the performance of fishes, affecting ecological processes such as competition.
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Competitive mechanisms change with ontogeny in coral-dwelling gobies
Ecology, 2015Co-Authors: Pedro Henrique Cipresso Pereira, Philip L Munday, Geoffrey P. JonesAbstract:Recent theory suggests that a mix of lottery and niche processes can facilitate coexistence between competing species, but this has not yet been empirically tested. Previous research has suggested that a competitive lottery for space promotes coexistence between two ecologically similar species, Gobiodon histrio and Gobiodon erythrospilus. However, not all the assumptions of lottery competition have been tested, and patterns of habitat use by adults suggest niche partitioning. Here, we investigated the hypothesis that the mechanism of competition changes with ontogeny, with a lottery for space operating at settlement and niche partitioning occurring in adults. Patterns of resource use in the field were compared for juveniles and adults of the two species. Pelagic larval duration (PLD) and size-at-settlement was also estimated to determine if size differences at settlement could affect the outcome of competitive interactions among juveniles. Habitat preference and size-based competitive ability were then tested for juveniles and adults in laboratory experiments. Finally, a transplant experiment was performed to test the fitness-associated consequences of niche partitioning among adults and its implications for coexistence of the two species. G. histrio had a similar PLD (20.7 ± 2.0 days) to G. erythrospilus (18.5 ± 1.9 days), and there was no difference in size-at-settlement between the species. Juveniles of the two species had similar patterns of habitat use and similar competitive abilities, supporting the lottery mechanism at settlement. However, adults differ in their habitat use, supporting the prediction that resource partitioning increases with ontogeny. In laboratory experiments, adults of each species preferred colonies of Acropora nasuta. However, G. histrio was a superior competitor and prevented G. erythrospilus from using A. nasuta in > 70% of the trials. In the field transplant experiment, G. erythrospilus (inferior competitor) suffered less of a fitness loss when occupying the non-preferred coral (A. spathulata) compared with G. histrio, which could explain its ability to persist when displaced by the superior competitor. These results suggest that the competitive mechanism operating between the two Gobiodon species shifts from a lottery for space to niche partitioning through ontogeny, and that these two mechanisms of competitive coexistence are not mutually exclusive.
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Aerobic vs. anaerobic scope: sibling species of fish indicate that temperature dependence of hypoxia tolerance can predict future survival
Global change biology, 2014Co-Authors: Christina Sørensen, Philip L Munday, Göran E. NilssonAbstract:The temperature dependence of aerobic scope has been suggested to be a major determinant of how marine animals will cope with future rises in environmental temperature. Here, we present data suggesting that in some animals, the temperature dependence of anaerobic scope (i.e., the capacity for surviving severe hypoxia) may determine present-day latitudinal distributions and potential for persistence in a warmer future. As a model for investigating the role of anaerobic scope, we studied two sibling species of coral-dwelling gobies, Gobiodon histrio, and G. erythrospilus, with different latitudinal distributions, but which overlap in equal abundance at Lizard Island (14°40'S) on the Great Barrier Reef. These species did not differ in the temperature dependence of resting oxygen consumption or critical oxygen concentration (the lowest oxygen level where resting oxygen consumption can be maintained). In contrast, the more equatorial species (G. histrio) had a better capacity to endure anaerobic conditions at oxygen levels below the critical oxygen concentration at the high temperatures (32–33 °C) more likely to occur near the equator, or in a warmer future. These results suggest that anaerobic scope, in addition to aerobic scope, could be important in determining the impacts of global warming on some marine animals.
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Habitat preferences of coral-associated fishes are altered by short-term exposure to elevated CO_2
Marine Biology, 2013Co-Authors: Brynn M. Devine, Philip L MundayAbstract:Rising atmospheric carbon dioxide (CO_2) concentrations are causing additional CO_2 to be absorbed by the oceans. Recent studies show that exposure to elevated CO_2 causes olfactory impairment in reef fishes; however, the ecological consequences of this impairment are largely unknown. This study examined the effects of short-term exposure to elevated CO_2 on habitat preferences of coral-dwelling gobies. Adult gobies collected from the reef at Lizard Island (Great Barrier Reef, Australia) were exposed for 4 days to ambient CO_2 (440 μatm) or elevated CO_2 (880 μatm). Habitat preferences were then tested in laboratory and field experiments at ambient conditions. In olfactory preference tests, ParaGobiodon xanthosomus displayed a strong preference for odour cues of their sole host coral Seriatopora hystrix ; however, this preference was absent in gobies exposed to elevated CO_2. Habitat choice experiments conducted in the field showed that Gobiodon histrio placed on dead coral colonies located preferred live habitat within 24 h; however, gobies exposed to elevated CO_2 associated with both preferred and non-preferred habitats in approximately equal frequency. Preferred habitats are known to confer fitness advantages to coral-dwelling gobies. Consequently, these results suggest that future elevated CO_2 levels might affect the ability of habitat specialist fishes to select favourable habitats.
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Phylogenetic evidence for recent diversification of obligate coral-dwelling gobies compared with their host corals
Molecular phylogenetics and evolution, 2013Co-Authors: David A. Duchêne, Philip L Munday, Jürgen Herler, Selma O. Klanten, Lynne Van HerwerdenAbstract:The rich diversity of coral reef organisms is supported, at least in part, by the diversity of coral reef habitat. Some of the most habitat specialised fishes on coral reefs are obligate coral-dwelling gobies of the genus Gobiodon that inhabit a range of coral species, mostly of the genus Acropora. However, the role of this specialised pattern of habitat use in the evolution of coral-dwelling gobies is not well understood. Diversification of coral-dwelling gobies may be driven by the diversification of their host corals (cospeciation), or alternatively, diversification of these fishes may have occurred independently of the diversification of host corals. The cospeciation hypothesis assumes similar timing in evolution of the gobies and their host corals. We used four genes for each group and the available fossil records to reconstruct and date phylogenies for 20 species of Gobiodon from the Indo-Pacific and the Red Sea, and for 28 species of the coral genus Acropora. Our results indicate that Gobiodon diversified mostly in the last ∼5 My, whereas Acropora corals have consistently diversified since the Eocene, making the hypothesis of cospeciation untenable. The fully resolved molecular phylogeny of the genus Gobiodon is in part at odds with previous analyses incorporating morphological data and indicates that some morphological traits form paraphyletic clades within Gobiodon. Our phylogeny supports a hypothesis in which Gobiodon diversified in the Indo-Pacific Ocean and then radiated recently, with multiple new variants found in the Red Sea.
Geoffrey P. Jones - One of the best experts on this subject based on the ideXlab platform.
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Competitive mechanisms change with ontogeny in coral-dwelling gobies
Ecology, 2015Co-Authors: Pedro Henrique Cipresso Pereira, Philip L Munday, Geoffrey P. JonesAbstract:Recent theory suggests that a mix of lottery and niche processes can facilitate coexistence between competing species, but this has not yet been empirically tested. Previous research has suggested that a competitive lottery for space promotes coexistence between two ecologically similar species, Gobiodon histrio and Gobiodon erythrospilus. However, not all the assumptions of lottery competition have been tested, and patterns of habitat use by adults suggest niche partitioning. Here, we investigated the hypothesis that the mechanism of competition changes with ontogeny, with a lottery for space operating at settlement and niche partitioning occurring in adults. Patterns of resource use in the field were compared for juveniles and adults of the two species. Pelagic larval duration (PLD) and size-at-settlement was also estimated to determine if size differences at settlement could affect the outcome of competitive interactions among juveniles. Habitat preference and size-based competitive ability were then tested for juveniles and adults in laboratory experiments. Finally, a transplant experiment was performed to test the fitness-associated consequences of niche partitioning among adults and its implications for coexistence of the two species. G. histrio had a similar PLD (20.7 ± 2.0 days) to G. erythrospilus (18.5 ± 1.9 days), and there was no difference in size-at-settlement between the species. Juveniles of the two species had similar patterns of habitat use and similar competitive abilities, supporting the lottery mechanism at settlement. However, adults differ in their habitat use, supporting the prediction that resource partitioning increases with ontogeny. In laboratory experiments, adults of each species preferred colonies of Acropora nasuta. However, G. histrio was a superior competitor and prevented G. erythrospilus from using A. nasuta in > 70% of the trials. In the field transplant experiment, G. erythrospilus (inferior competitor) suffered less of a fitness loss when occupying the non-preferred coral (A. spathulata) compared with G. histrio, which could explain its ability to persist when displaced by the superior competitor. These results suggest that the competitive mechanism operating between the two Gobiodon species shifts from a lottery for space to niche partitioning through ontogeny, and that these two mechanisms of competitive coexistence are not mutually exclusive.
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Social induction of maturation and sex determination in a coral reef fish.
Proceedings. Biological sciences, 2004Co-Authors: Jean-paul A. Hobbs, Philip L Munday, Geoffrey P. JonesAbstract:Labile maturation and sex determination should be advantageous where the probability of finding a mating partner is unpredictable. Here we tested the hypothesis that the presence of a potential mating partner induces maturation and sex determination in a coral-dwelling fish, Gobiodon erythrospilus. In natural populations at Lizard Island (Great Barrier Reef), single individuals were less likely to be mature than paired individuals and they matured at a larger size, indicating plasticity in the timing of maturation. By manipulating group structure we demonstrated that both the timing of maturation and the sex of maturing individuals are socially controlled. Single juveniles did not mature, but maturation was rapidly induced by the presence of an adult partner. In addition, sex determination was found to be labile, with juveniles maturing into the opposite sex of the partner encountered. To our knowledge, this is the first experimental demonstration of social induction of maturation in conjunction with labile sex determination at maturation in vertebrates. This flexibility enables individuals to maximize their reproductive success in an environment where the timing of mate acquisition and the sex of their future partner are unpredictable.
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Skin toxins and external parasitism of coral-dwelling gobies
Journal of Fish Biology, 2003Co-Authors: Philip L Munday, Geoffrey P. Jones, M. J. Caley, M. Schubert, J. A. Baggio, Alexandra S. GrutterAbstract:Toxic (Gobiodon spp.) and non-toxic (ParaGobiodon xanthosomus) gobies became infected with external parasites (gnathiid isopods) at equal rates in a laboratory experiment. Parasites were evenly distributed over the body of P. xanthosomus but were mostly confined to the fins of Gobiodon spp., where toxin glands are less abundant. Skin toxins were not associated with the rate of infection but their distribution did appear to influence the site of parasite attachment.
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The Toxicity of Skin Secretions from Coral-Dwelling Gobies and their Potential Role as a Predator Deterrent
Environmental Biology of Fishes, 2003Co-Authors: Melissa Schubert, Philip L Munday, Geoffrey P. Jones, M. Julian Caley, Lyndon E. LlewellynAbstract:Coral-dwelling gobies in the genus Gobiodon (family Gobiidae) posses toxic skin secretions. We used bioassays to investigate interspecific variation in the toxicity of skin secretions from six species of Gobiodon from Lizard Island on the Great Barrier Reef. We then used feeding experiments with two common species of predatory fish to test if skin secretions might act as a chemical defence against predation. The skin secretions of all species were toxic to the bioassay species, Apogon fragilis, but there were marked differences in toxicity among Gobiodon species. Feeding experiments showed that both small- and large-gaped predators avoided food items to which goby skin secretions, or a whole goby, had been added. These experiments indicate that skin toxins could function as a predator deterrent in coral-dwelling gobies.
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INTERSPECIFIC COMPETITION AND COEXISTENCE IN A GUILD OF CORAL-DWELLING FISHES
Ecology, 2001Co-Authors: Philip L Munday, Geoffrey P. Jones, M. Julian CaleyAbstract:We investigated the effects of interspecific competition on abundance, habitat partitioning, and coexistence of six closely related species of gobies (genus Gobiodon) that inhabit a range of acroporid coral species at Lizard Island, Great Barrier Reef. After documenting the extent of overlap in habitat use among pairs of species in the field, we used a combination of field and laboratory experiments to investigate the relationship between these patterns and the occurrence of interspecific competition. Experiments in aquaria tested the ability of five of the species to compete against G. histrio, the apparent competitive dominant, including the effects of body size and prior residency. A manipulative field experiment, in which abundance of G. histrio was reduced, tested whether competition with this species limits the abundance of the other five species. Two species competed for space with G. histrio in the field, yet overlap in habitat use with G. histrio was high for one of these species (G. axillaris) and low for the other (G. brochus). In aquaria, G. axillaris and G. histrio preferred the same species of coral and had equivalent, size-based, competitive abilities. The coexistence of G. axillaris and G. histrio at the scale of 10’s metres on the reef can thus be explained by a competitive lottery model. However, differential distributions of these two species across the reef flat and reef crest suggests that resource partitioning or habitat selection at larger spatial scales are also important to their coexistence. In aquaria, G. brochus was an inferior competitor to G. histrio and could only gain access to the preferred species of coral through an advantage in body size or prior residency. Low overlap in habitat use between G. brochus and G. histrio in the field appears to result from niche shifts by the subordinate competitor only, indicating coexistence via an included niche model. The field experiment indicated that the other three other species did not compete for space with G. histrio, and these species exhibited either low (G. rivulatus) or high (G. quinquestrigatus and G. unicolor) overlap in habitat use with G. histrio. Experiments in aquaria demonstrated that G. rivulatus and G. histrio did not compete because they preferred different species of coral. In contrast, G. unicolor and G. histrio exhibited high overlap in habitat use but did not compete because they were able to co-habit the same coral colonies without affecting each other. In aquaria, G. quinquestrigatus and G. histrio preferred the same coral species and G. quinquestrigatus was an inferior competitor, so these species were expected to compete for space in the field. In a field recolonization experiment, coral colonies previously occupied by G. quinquestrigatus were rarely recolonized by G. histrio, indicating that these species coexist because they use different types of coral colonies in the field. The study demonstrates that there is no single relationship between overlap in resource use and the occurrence of interspecific competition, even among closely related species, and that species within a guild can coexist by a diversity of mechanisms.
Juergen Herler - One of the best experts on this subject based on the ideXlab platform.
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Microhabitat characteristics influence shape and size of coral-associated fishes
Marine Ecology Progress Series, 2014Co-Authors: Florian Wehrberger, Juergen HerlerAbstract:Coral reefs provide a high diversity of habitats, including the often complex structure of reef-building corals themselves. Since these coral microhabitats are constrained spatially, specific phenotypic adaptations of associated species to the geometric structure of corals are expected. In the northern Red Sea, we investigated how the physical structure of 2 Acropora corals influences the size, shape and growth of fishes that live in these corals. Branch length and interbranch distance increased strongly and differentially with colony size in both coral species, making large colonies more suitable for larger fishes. We used traditional and geometric morphometrics to demonstrate that the 2 coral-dwelling gobies Gobiodon histrio (Valenciennes) and G. rivulatus (Rueppell) follow different ontogenetic growth patterns. Adult G. histrio show a dorsoventrally expanded body combined with a lateral compression, while the wider-bodied G. rivulatus has a smaller maximum body length. The lateral compression enables G. histrio to pass smaller interbranch distances than G. rivulatus of the same body length, as demonstrated in an experiment testing their ability to pass narrow interbranch distances. Measurements of G. histrio revealed a greater increase of body length and mass with coral colony size in Acropora digitifera than in A. gemmifera or other coral species. Outliers in growth rates of the fishes demonstrated that moving to larger corals and/or associating with a larger breeding partner benefits fish growth. Shape-related lateral body size differences provide an explanation why those fishes that are better adapted to certain host corals compete more successfully for these microhabitats. The evolution of different shapes in coral-associated fishes indicates differences in habitat specialization to reef-building corals with different geometries.
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Coral architecture affects the habitat choice and form of associated gobiid fishes
Marine Biology, 2014Co-Authors: Lucien Untersteggaber, Philipp Mitteroecker, Juergen HerlerAbstract:Gobiid fishes of the genus Gobiodon live in strong association with certain reef-building corals that vary considerably in size and architecture. These fishes hence are excellent model systems for studying evolutionary adaption to specific microhabitats. Using a sample of Gobiodon histrio and G. rivulatus and their most important host corals ( Acropora digitifera and A. gemmifera) from the northern Red Sea, we assess (1) how corals that are occupied by gobies differ in their architecture from colonies that are not occupied and (2) how fish body shape is associated with the architecture of their host coral. Fish body shape was assessed by geometric morphometric techniques. Coral measurements included colony size, branch length (BL), and interbranch as well as branch tip distance of adjacent branches, for which we applied a new and non-destructive measurement technique based on casts of two-component epoxy resin. The most important factor influencing the occupation of corals was a BL of more than 5 cm. The distance between coral branches was clearly related to the width of the fishes and hence constrained overall fish size. G. histrio and G. rivulatus differ in adult body shape as well in their allometric development of lateral body compression, resulting in different maximum body sizes attainable in the restricted interbranch space of corals. The strong dependence of coral-associated fishes on large coral colonies with specific architectures increases the extinction risk of fishes within deteriorating coral reefs.
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Skin toxins in coral-associated Gobiodon species (Teleostei: Gobiidae) affect predator preference and prey survival
Marine ecology (Berlin Germany), 2014Co-Authors: Barbara Gratzer, Eva Millesi, Manfred Walzl, Juergen HerlerAbstract:Predation risk is high for the many small coral reef fishes, requiring successful sheltering or other predator defence mechanisms. Coral-dwelling gobies of the genus Gobiodon live in close association with scleractinian corals of the genus Acropora. Earlier studies indicated that the low movement frequency of adult fishes and the development of skin toxins (crinotoxicity) are predation avoidance mechanisms. Although past experiments showed that predators refuse food prepared with goby skin mucus, direct predator–prey interactions have not been studied. The present study compares the toxicity levels of two crinotoxic coral gobies – Gobiodon histrio, representative of a conspicuously coloured species, and Gobiodon sp.3 with cryptic coloration – using a standard bioassay method. The results show that toxin levels of both species differ significantly shortly after mucus release but become similar over time. Predator preferences were tested experimentally in an aquarium in which the two gobies and a juvenile damselfish Chromis viridis were exposed to the small grouper Epinephelus fasciatus. Video-analysis revealed that although coral gobies are potential prey, E. fasciatus clearly preferred the non-toxic control fish (C. viridis) over Gobiodon. When targeting a goby, the predator did not prefer one species over the other. Contrary to our expectations that toxic gobies are generally avoided, gobies were often captured, but they were expelled quickly, repeatedly and alive. This unusual post-capture avoidance confirms that these gobies have a very good chance of surviving attacks in the field due to their skin toxins. Nonetheless, some gobies were consumed: the coral shelter may therefore also provide additional protection, with toxins protecting them mainly during movement between corals. In summary, chemical deterrence by crinotoxic fishes seems to be far more efficient in predation avoidance than in physical deterrence involving body squamation and/or strong fin spines.
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Four new species of coral gobies (Teleostei: Gobiidae: Gobiodon), with comments on their relationships within the genus.
Zootaxa, 2013Co-Authors: Juergen Herler, Sergey V. Bogorodsky, Toshiyuki SuzukiAbstract:Four new species of the coral-associated gobiid genus Gobiodon were discovered in the Red Sea. Although several of these species are common not only in the Red Sea but also in the Indian and western Pacific Ocean, they have not been described before. Detailed descriptions of the four species are based on morphological and molecular genetic (mitochondrial 12s and 16s rRNA) investigations. The new species, like most species of the genus, lack scales and have species-specific life colouration. Gobiodon bilineatus sp. nov. is the closest relative to G. quinquestrigatus (Valenciennes) and of G . sp. D (Munday et al .), and has five distinct, blue lines on the head as juveniles and subadults, which disappear in adults, and which are often uniformly orange-red with two distinct, vertical blue lines through each eye. Gobiodon irregularis sp. nov. has been confused with the former new species in the past, and is closely related to G. oculolineatus Wu, but is unmistakable in live colouration. Juveniles are characterised by a transparent body, red bars on the head with bluish to greyish interspaces, and irregular red lines and dots on the nape and dorsally on the body. Adults are usually uniformly brown or green-brown, with only remnants of the bars through the eye and below the orbit. Gobiodon ater sp. nov. is a small, entirely black species and can be easily confused with other black species, although it is genetically clearly distinct from G. ceramensis Bleeker and its black relatives. Gobiodon fuscoruber sp. nov. is likely to be the closest relative of G. ater sp. nov., but is uniformly reddish-brown or brown, has bright median fin margins (at least in the Red Sea), and grows considerably larger than G. ater . It has been genetically determined that G. fuscoruber sp. nov. is identical with an Indian Ocean/western Pacific species that has been called G. unicolor Castelnau by several authors. However, examination of the holotype of G. unicolor , including the original description, revealed that the type species and original description are clearly different from the species frequently called G. unicolor . The holotype resembles G. histrio (Valenciennes) and the name G. unicolor must therefore be considered a junior synonym of G. histrio . As a consequence, a new name for this species is provided.
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Gobies on coral reefs
2011Co-Authors: Juergen Herler, Philip L Munday, V. HernamanAbstract:[Extract] The family Gobiidae comprises at least 2000 species (Nelson, 2006), with many still undiscovered or undescribed. More than half of all goby species are found on coral reefs and thus they contribute greatly to the astonishing fish diversity of this environment. Most coral reef gobies are closely associated with the substratum, where they seek shelter from predators in the complex physical structure of reef habitat (Munday and Jones, 1998). As a consequence of their small size and cryptic life-style, careful investigations by trained experts are necessary to reveal their full diversity. Although there are few such researchers, new species are still being described discovered (e.g., Coryphopterus (Victor, 2007), Eviota (Gill and Jewett, 2004), Gobiodon (Harold and Winterbottom, 1995; Harold and Winterbottom, 1999; Winterbottom and Harold, 2005), Priolepis (Nogawa and Endo, 2007) and Trimma (e.g. Winterbottom, 2004, 2006; Hagiwara and Winterbottom, 2007; Suzuki and Senou, 2007; Winterbottom and Zur, 2007). Despite the diversity of coral reef gobies – the genus Trimma, for example, may include nearly 100 species (Winterbottom and Southcott, 2008) – most species are easily overlooked and are commonly excluded from sampling or ecological surveys. However, a recent upsurge of interest in the ecological role of small reef fishes (e.g., Munday and Jones, 1998; Depczynski and Bellwood, 2003) and the use of several coral-reef goby genera as model groups in ecology and evolution (e.g., Forrester and Steele, 2000; Munday et al., 2001; Taylor and Hellberg, 2003; Munday, 2004b) has greatly increased our understanding of the biology and ecology of this diverse and interesting group of coral reef fishes. In this chapter we examine the ecology, life-histories and reproductive behaviour of coral reef gobies. We also explore morphological adaptations that are associated with the unique life-styles exhibited by many coral reef gobies, and the extreme miniaturization of certain groups of species. Although frequently overlooked in studies of reef fish assemblages due to their small size and cryptic behaviour, we show that gobies play an important role in coral reef ecoystems, and that they have proven to be a useful model group for studying a broad range of topics in ecology and evolution, including: species diversification, ecological and morphological adaptation, the evolution of animal life history traits, mechanisms of community structure and population regulation, and the evolution of animal behaviour.
Jürgen Herler - One of the best experts on this subject based on the ideXlab platform.
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Phylogenetic evidence for recent diversification of obligate coral-dwelling gobies compared with their host corals
Molecular phylogenetics and evolution, 2013Co-Authors: David A. Duchêne, Philip L Munday, Jürgen Herler, Selma O. Klanten, Lynne Van HerwerdenAbstract:The rich diversity of coral reef organisms is supported, at least in part, by the diversity of coral reef habitat. Some of the most habitat specialised fishes on coral reefs are obligate coral-dwelling gobies of the genus Gobiodon that inhabit a range of coral species, mostly of the genus Acropora. However, the role of this specialised pattern of habitat use in the evolution of coral-dwelling gobies is not well understood. Diversification of coral-dwelling gobies may be driven by the diversification of their host corals (cospeciation), or alternatively, diversification of these fishes may have occurred independently of the diversification of host corals. The cospeciation hypothesis assumes similar timing in evolution of the gobies and their host corals. We used four genes for each group and the available fossil records to reconstruct and date phylogenies for 20 species of Gobiodon from the Indo-Pacific and the Red Sea, and for 28 species of the coral genus Acropora. Our results indicate that Gobiodon diversified mostly in the last ∼5 My, whereas Acropora corals have consistently diversified since the Eocene, making the hypothesis of cospeciation untenable. The fully resolved molecular phylogeny of the genus Gobiodon is in part at odds with previous analyses incorporating morphological data and indicates that some morphological traits form paraphyletic clades within Gobiodon. Our phylogeny supports a hypothesis in which Gobiodon diversified in the Indo-Pacific Ocean and then radiated recently, with multiple new variants found in the Red Sea.
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Phylogenetic relationships of coral-associated gobies (Teleostei, Gobiidae) from the Red Sea based on mitochondrial DNA data
Marine Biology, 2009Co-Authors: Jürgen Herler, Stephan Koblmüller, Christian SturmbauerAbstract:Bryaninops , Gobiodon , ParaGobiodon and Pleurosicya are the most abundant genera of coral-associated gobies. These genera are adapted to live among coral, while other small reef gobies (e.g., the genus Eviota ) show no obligate association with this living substrate. Thirteen coral-associated species and two Eviota species were sampled from different regions of the Red Sea, along with four populations/species of Gobiodon from the Indian and western Pacific Oceans. A molecular phylogenetic analysis was performed using partial sequences of 12S rRNA, 16S rRNA and cytochrome b mitochondrial genes, 1,199 base pairs in total. Several clades were consistently resolved in neighbor joining-, maximum parsimony-, maximum likelihood and Bayesian analyses. While each of the four genera Gobiodon , ParaGobiodon , Bryaninops and Pleurosicya proved to be monophyletic, their relative position in the phylogeny did not support an emergence of coral-associated gobiids as a monophyletic assemblage. Instead, two separate monophyletic sub-groups were discovered, the first comprising Gobiodon and ParaGobiodon , and the second Bryaninops and Pleurosicya . Our molecular phylogenetic examinations also revealed one unassigned species of Gobiodon from the Maldives as a distinct species and confirmed three putative and yet unassigned species from the Red Sea. Moreover, the uniformly black colored species of Gobiodon are not monophyletic but have evolved independently within two distinct species groups. Genetic distances were large in particular within Pleurosicya and Eviota . Estimated divergence times suggest that coral-associated gobies have diversified in parallel to their preferred host corals. In particular, divergence times of Gobiodon species closely match those estimated for their typical host coral genus Acropora .
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Postsettlement movement patterns and homing in a coral-associated fish
Behavioral Ecology, 2008Co-Authors: Marlene Wall, Jürgen HerlerAbstract:Coral-associated gobies are highly specialized reef fishes with high host-coral fidelity. Flexibility in habitat choice, however, is important to compensate for potential habitat alteration or loss, but detailed information about the postsettlement movement behavior of such gobies is lacking. We examined movement patterns in Gobiodon histrio, both under natural conditions and during subsequent field experiments, involving breeding pair or partner removal from 3 of the 4 investigation plots. Additionally, we investigated homing behavior, and 2 aquaria experiments were designed to assess home coral and partner recognition of adult fish taken from breeding pairs. Under natural conditions, the movement rate was high for single adults, whereas breeding pairs showed high home-coral fidelity. Manipulations revealed little change of natural patterns except in single adults, which slightly decreased their movement rate in the breeding pair removal plot. In the homing experiment, 17% of tested fish returned to their home coral even after displacement of 4 m, and homing success was much higher at shorter distances (100% at 0.5 m, 53% at 2.25 m). In the aquarium, G. histrio exhibited higher recognition of its home-coral colony (75%) than of its breeding pair partner (60%). Our study shows that G. histrio frequently moves between corals, although this depends on the social status (juvenile, single adult, breeding pair) of the individuals. The high proportion and movement rate of single adults indicate low sensitivity to habitat alteration but also limited high-quality habitats in which breeding pairs could be established. Hence, vulnerability to habitat loss increases when individuals breed. Key words: coral reefs, Gobiodon histrio, habitat fidelity, migration, reef fish, Red Sea. [Behav Ecol]
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Microhabitats and ecomorphology of coral‐ and coral rock‐associated gobiid fish (Teleostei: Gobiidae) in the northern Red Sea
Marine Ecology, 2007Co-Authors: Jürgen HerlerAbstract:Twenty-one coral- and coral rock-associated gobiid fish species were examined in the Gulf of Aqaba, northern Red Sea in autumn 2003 and spring 2004. They represent the seven genera Bryaninops, Eviota, Gobiodon, ParaGobiodon, Pleurosicya, Priolepis and Trimma. All species showed clear spatial niche segregation. Branching corals of the genus Acropora were obligatorily inhabited by Gobiodon spp., while ParaGobiodon echinocephalus was restricted to Stylophora pistillata. Three Bryaninops species showed species-specific associations with Acropora spp., Millepora dichotoma and Cirripathes sp. Most of the five Eviota species had weak associations with live corals but frequented coral rock. Among the genus Pleurosicya, two species were encountered. Pleurosicya micheli frequented massive scleractinian corals, while P. prognatha occupied various species of Acropora. Priolepis semidoliata was only occasionally observed on coral rock. Weak associations with scleractinian corals were documented in Trimma avidori and T. mendelssohni, both of which inhabit coral rock. Principal component and cluster analyses showed several morphological features to be important ecomorphological traits. Gobiid species inhabiting encrusting or massive corals have a more depressed body than species in branching corals. Eye size was well correlated with preferred water depth, especially in the coral-associated species. A typical gobiid feature ‐ the pelvic disc ‐ was found in very different character states, and corresponded to preferred microhabitats. A well-developed suctorial pelvic disc was typical for obligate coral-dwellers.
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Microhabitat specialisation and ecological consequences for coral gobies of the genus Gobiodon in the Gulf of Aqaba, northern Red Sea
Marine Ecology Progress Series, 2007Co-Authors: Markus Dirnwöber, Jürgen HerlerAbstract:The microhabitat selection and distribution of 6 coral-associated species of Gobiodon were examined in the Gulf of Aqaba, northern Red Sea, including 3 recently discovered species. A total of 1626 fishes were counted visually using 10 × 1 m belt transects in 1731 colonies of 13 species of Acropora. Niche segregation was observed at the level of coral species. Gobiodon sp. 2 was the most specialised, occupying only A. hyacinthus; Gobiodon sp. 1 was most generalised (occupying 3 species of Acropora more frequently than expected). G. reticulatus was a zone specialist that pre- ferred deeper water regions. Less specialised species were able to use substitute host corals, which enabled them to maintain extraordinarily high abundance. G. histrio, for example, preferred the rare A. digitifera, but was common in the very abundant A. acuminata, although proportionally fewer breeding pairs were established in the latter. When compared to the western Pacific, G. histrio showed a more generalised behaviour in the northern Red Sea, and different coral species served as host corals; the latter also holds true for the even more generalised G. rivulatus. Hence, species of Gobiodon appear to alter host-use and degree of specialisation on a global scale.
J. Herler - One of the best experts on this subject based on the ideXlab platform.
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Toxic coral gobies reduce the feeding rate of a corallivorous butterflyfish on Acropora corals
Coral Reefs, 2013Co-Authors: M. Dirnwoeber, J. HerlerAbstract:The obligate coral-dwelling gobiid genus Gobiodon inhabits Acropora corals and has developed various physiological, morphological and ethological adaptations towards this life habit. While the advantages of this coral-fish association are well documented for Gobiodon , possible fitness-increasing factors for the host coral are unknown. This study examines the influence of coral-dwelling gobies on the feeding behaviour of obligate corallivorous butterflyfishes. In an aquarium experiment using video observation, the corallivorous butterflyfish Chaetodon austriacus fed significantly less on corals inhabited by two Gobiodon species compared to unoccupied coral colonies of similar size. The more agonistic species G. histrio , which mostly displayed directed movements towards butterflyfishes, decreased butterflyfish bite rate by 62–98 % compared to uninhabited colonies. For Gobiodon sp. 3, which mostly displayed undirected movements in response to visits by C. austriacus , bite rate reduction was 64–68 %. The scale-less skin of Gobiodon spp. is covered by mucus that is toxic and multi-functional by reducing predation as well as affecting parasite attachment. A choice flume experiment suggests that the highly diluted skin mucus of Gobiodon spp. also functions as a corallivore repellent. This study demonstrates that Gobiodon spp. exhibit resource defence against coral-feeding butterflyfishes and also that coral colonies without resident Gobiodon suffer higher predation rates. Although the genus Gobiodon is probably a facultative corallivore, this study shows that by reducing predation on inhabited colonies by other fishes, these obligate coral-dwellers either compensate for their own fitness-decreasing impact on host colonies or live in a mutualistic association with them.
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Food selection of a corallivorous butterflyfish Chaetodon austriacus in the Red Sea, with particular emphasis on size and fish symbionts of corals
Journal of fish biology, 2009Co-Authors: S. K. Niedermüller, L. S. Schiemer, J. HerlerAbstract:The exquisite butterflyfish Chaetodon austriacus feeds mainly on Acropora, Pocillopora, Montipora and Stylophora in the northern Red Sea. Large colonies of Acropora are preferred over smaller colonies and other coral genera, whereas avoidance is indicated for corals that are occupied by certain coral-associated gobiid fishes of the genus Gobiodon. It is suggested that, apart from coral identity, colony size and potential repellent effects of particular coral symbionts are both important sources of variation in the food selectivity of corallivorous chaetodotids.
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trophic morphology of the coral associated genus Gobiodon teleostei gobiidae from the red sea
Journal of Zoological Systematics and Evolutionary Research, 2009Co-Authors: E. Riedlecker, J. HerlerAbstract:Trophic morphology plays a major role in niche diversification among the highly diverse fish fauna of coral reefs. It gives insight into feeding types and is useful in taxonomy, as it can be used to differentiate between species and to estimate phylogenetic relationships. The gobiid genus Gobiodon comprises obligate coral dwelling species that are widespread on Red Sea and Indo-Pacific reefs. Yet very little is known about their ecology and behaviour of feeding. In this study, viscerocranial and oral jaw morphology was investigated in seven species of Gobiodon that occur in the Red Sea. Osteological analyses were carried out on enzyme cleared and alizarin red stained specimens. Shape variation of the viscerocranium was analyzed using a landmark-based geometric morphometric method on digital scans of hand drawings and visualized in thin-plate splines. Shape was determined by placing landmarks on skeletal elements in their articulated state. Morphology of the dentary and premaxilla was examined in further detail after disarticulation. A combination of landmarks and semilandmarks was applied to digital photographs of the oral jaws. It was shown that orbit size influences viscerocranial morphology by delimiting the lower jaw articulation angle. The premaxilla differs both in its extent and direction of curvature and in the structure of the articular process. Form changes in the dentary are mainly caused by variation of curvature and depth. A significant relationship between oral jaw shape and the number of anterior rows of teeth was found. Morphological diversity of selected elements is used to generate hypotheses concerning the trophic biology and niche diversification of Gobiodon. Brief dietary and in situ behavioural observations were carried out to further develop and test hypotheses. Zusammenfassung Korallenassoziierte Fische der Gattung Gobiodon gehoren zu den okologisch interessantesten Formen der artenreichsten marinen Fischfamilie der Meergrundeln (Gobiidae). Im Roten Meer leben 7 Arten dieser Gattung, die sich durch charakteristische Habitatwahl mit Praferenzen fur unterschiedliche Mikrohabitate (verschiedene Korallenarten der Gattung Acropora) auszeichnen (Herler and Hilgers 2005; Dirnwober and Herler 2007). Diese Eigenschaft und ihre hohen Anpassungen an lebende Korallen haben sie zu einer besonderen Modellgruppe fur eine Reihe okologischer und evolutionsbiologischer Fragestellungen gemacht. Die meisten dieser Arbeiten haben sich bisher mit Habitatspezialisation (Munday et al. 1997; Dirnwober and Herler 2007), inter- und intraspezifischer Konkurrenz (Munday et al. 2001; Hobbs and Munday 2004) befasst und auch sympatrische Speziation als Moglichkeit der Radiation in Erwagung gezogen (Munday et al. 2004). Wenige Studien haben sich jedoch intensiv mit der morphologischen Vielfalt dieser diversen Gruppe beschaftigt (Harold et al. 2008) und speziell trophisch-morphologische Arbeiten fehlen ganz. Die vorliegende Studie hatte eine quantitiativ-morphologische Untersuchung des Viscerocraniums und der Kiefer der 7 Gobiodon-Arten des Roten Meeres zum Ziel. Da die zwischenartliche Variabilitat ein Indikator fur unterschiedliche trophische Nischen sein kann (Wainwright and Bellwood 2001), wurde ein Beweis dieser ein weiteres System zur Erklarung der Radiation dieser Gruppe liefern. Dazu wurden Formvariablen mittels geometrischer Morphometrie basierend auf Landmarken von aufgehellten und gefarbten Fischen aufgenommen. Die Landmarken fur die Viscerocrania wurden auf digitalisierte Handzeichnungen appliziert, jene der Kiefer auf Digitalfotos der spater disartikulierten Ober- und Unterkiefer. Statistische Analysen der Formvariablen zeigten zwischenartliche Unterschiede, vor allem im Viscerocranium und Oberkiefer, und einen Zusammenhang zwischen Augengrose und Viscerocraniumform. Grosere Augen hatten lang gestreckte Viscerocrania und flache Suspensorium-Winkel zur Folge. Des Weiteren wurde eine positive Korrelation zwischen der Anzahl der Zahnreihen und der Krummung des Unter- und Oberkiefers gefunden. Formunterschiede in den Kiefern lassen unterschiedliche funktionsmorphologische Aspekte fur einige Arten vermuten. Nachdem die Ahnlichkeit der trophischen Morphen im Wesentlichen jene der morphologischen und genetischen Phylogenie der Gruppe (J. Herler, unpublizierte Daten) entsprechen, lasst sich keine Radiation durch trophische Nischendiversifikation in den rezenten Arten vermuten, da keine konvergenten Entwicklungen beobachtet werden konnten.
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The influence of colony size and coral health on the occupation of coral-associated gobies (Pisces: Gobiidae)
Coral Reefs, 2009Co-Authors: L. Schiemer, S. Niedermüller, J. HerlerAbstract:Fishes of the genus Gobiodon are habitat specialists by their association with Acropora corals. Little is known about the parameters that define host coral quality for these fishes, in particular their breeding pairs. Data were collected in the northern Red Sea using 10 × 1-m belt transects in different reefs and zones. Gobiid density was highly correlated with coral density over all sites and zones, and the more specialized goby species preferred coral species that are less vulnerable to environmental stress. Moreover, the occupation rate of corals by goby breeding pairs significantly increased with colony size and decreased with partial mortality of colonies. Logistic regression showed that both coral size (being most important) and partial mortality are key factors influencing the occupation by breeding pairs. This study provides the first evidence that breeding pairs of coral-associated gobiids have more advanced habitat requirements than con-specifics in other social states. As coral reefs are threatened worldwide and habitat loss and degradation increase, this information will help predict the potential effects on those reef fishes obligatorily associated with live corals.
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Trophic morphology of the coral‐associated genus Gobiodon (Teleostei: Gobiidae) from the Red Sea
Journal of Zoological Systematics and Evolutionary Research, 2009Co-Authors: E. Riedlecker, J. HerlerAbstract:Trophic morphology plays a major role in niche diversification among the highly diverse fish fauna of coral reefs. It gives insight into feeding types and is useful in taxonomy, as it can be used to differentiate between species and to estimate phylogenetic relationships. The gobiid genus Gobiodon comprises obligate coral dwelling species that are widespread on Red Sea and Indo-Pacific reefs. Yet very little is known about their ecology and behaviour of feeding. In this study, viscerocranial and oral jaw morphology was investigated in seven species of Gobiodon that occur in the Red Sea. Osteological analyses were carried out on enzyme cleared and alizarin red stained specimens. Shape variation of the viscerocranium was analyzed using a landmark-based geometric morphometric method on digital scans of hand drawings and visualized in thin-plate splines. Shape was determined by placing landmarks on skeletal elements in their articulated state. Morphology of the dentary and premaxilla was examined in further detail after disarticulation. A combination of landmarks and semilandmarks was applied to digital photographs of the oral jaws. It was shown that orbit size influences viscerocranial morphology by delimiting the lower jaw articulation angle. The premaxilla differs both in its extent and direction of curvature and in the structure of the articular process. Form changes in the dentary are mainly caused by variation of curvature and depth. A significant relationship between oral jaw shape and the number of anterior rows of teeth was found. Morphological diversity of selected elements is used to generate hypotheses concerning the trophic biology and niche diversification of Gobiodon. Brief dietary and in situ behavioural observations were carried out to further develop and test hypotheses. Zusammenfassung Korallenassoziierte Fische der Gattung Gobiodon gehoren zu den okologisch interessantesten Formen der artenreichsten marinen Fischfamilie der Meergrundeln (Gobiidae). Im Roten Meer leben 7 Arten dieser Gattung, die sich durch charakteristische Habitatwahl mit Praferenzen fur unterschiedliche Mikrohabitate (verschiedene Korallenarten der Gattung Acropora) auszeichnen (Herler and Hilgers 2005; Dirnwober and Herler 2007). Diese Eigenschaft und ihre hohen Anpassungen an lebende Korallen haben sie zu einer besonderen Modellgruppe fur eine Reihe okologischer und evolutionsbiologischer Fragestellungen gemacht. Die meisten dieser Arbeiten haben sich bisher mit Habitatspezialisation (Munday et al. 1997; Dirnwober and Herler 2007), inter- und intraspezifischer Konkurrenz (Munday et al. 2001; Hobbs and Munday 2004) befasst und auch sympatrische Speziation als Moglichkeit der Radiation in Erwagung gezogen (Munday et al. 2004). Wenige Studien haben sich jedoch intensiv mit der morphologischen Vielfalt dieser diversen Gruppe beschaftigt (Harold et al. 2008) und speziell trophisch-morphologische Arbeiten fehlen ganz. Die vorliegende Studie hatte eine quantitiativ-morphologische Untersuchung des Viscerocraniums und der Kiefer der 7 Gobiodon-Arten des Roten Meeres zum Ziel. Da die zwischenartliche Variabilitat ein Indikator fur unterschiedliche trophische Nischen sein kann (Wainwright and Bellwood 2001), wurde ein Beweis dieser ein weiteres System zur Erklarung der Radiation dieser Gruppe liefern. Dazu wurden Formvariablen mittels geometrischer Morphometrie basierend auf Landmarken von aufgehellten und gefarbten Fischen aufgenommen. Die Landmarken fur die Viscerocrania wurden auf digitalisierte Handzeichnungen appliziert, jene der Kiefer auf Digitalfotos der spater disartikulierten Ober- und Unterkiefer. Statistische Analysen der Formvariablen zeigten zwischenartliche Unterschiede, vor allem im Viscerocranium und Oberkiefer, und einen Zusammenhang zwischen Augengrose und Viscerocraniumform. Grosere Augen hatten lang gestreckte Viscerocrania und flache Suspensorium-Winkel zur Folge. Des Weiteren wurde eine positive Korrelation zwischen der Anzahl der Zahnreihen und der Krummung des Unter- und Oberkiefers gefunden. Formunterschiede in den Kiefern lassen unterschiedliche funktionsmorphologische Aspekte fur einige Arten vermuten. Nachdem die Ahnlichkeit der trophischen Morphen im Wesentlichen jene der morphologischen und genetischen Phylogenie der Gruppe (J. Herler, unpublizierte Daten) entsprechen, lasst sich keine Radiation durch trophische Nischendiversifikation in den rezenten Arten vermuten, da keine konvergenten Entwicklungen beobachtet werden konnten.