Competition not only occurs between species, but (probably more importantly) also among individuals within species, especially, for species occurring in high densities and when resources are ...limiting. Fluctuating densities and dietary overlap may account for massive ecological and evolutionary changes in fish communities. We sampled a mixed juvenile (0+ stages, being younger than 1 year of age) fish community at the Lower Rhine over three consecutive years, including native and newly established species (~ 64,000 captured individuals and ~ 4200 dissected fish). Our aim was to develop a new approach in which data on density, individual consumption rates, and diet overlaps (both intra- and interspecific) solely originating from the natural environment, were used and combined to estimate species-specific competitive strengths within and between seasons and species. The juvenile fish community at the food-limited Rhine was dominated by invasive gobies. Species-specific consumption rates decreased depending on the dietary overlap with other juveniles. Two invasive gobies (
Neogobius melanostomus
and
N. fluviatilis
) showed the greatest competitive abilities, followed by a third invasive Gobiid species (
Ponticola kessleri
) and the native
Aspius aspius
, a species utilizing an exclusive food source. Both other native species (
Perca fluviatilis
and
Sander lucioperca
) had the lowest estimates of food-related competitive strength, indicating that these species are forced into a juvenile competitive bottleneck by the invasive gobies, before they finally can develop into successful predators on gobies later in life. Our new analytical approach to measure dietary competitive strength among individuals provides a powerful tool to empirically study eco-evolutionary feedback dynamics in the field.
Stiphodon surrufus Watson & Kottelat, 1995, with its recent synonym S. birdsong Watson, 1996, is recorded from widely separated locations in the Western Pacific, including Papua and Halmahera in ...eastern Indonesia. We collected a single specimen of male S. surrufus from the Bohi River, Banggai District, Central Sulawesi Province, Indonesia in 2019; this represents the first record of S. surrufus from Sulawesi, the largest island in the Wallacea biodiversity hotspot. Three additional specimens were collected in 2020, one in 2021, and two in 2022, all from the same site. These records expand the known distribution of a naturally rare but widespread sicydiine goby and contribute to the underexplored but increasingly threatened Sulawesian riverine ichthyofauna.
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•Phylogeny of 827 taxa from 17% complete supermatrix of 23 loci.•Resolves goby lineages and gobiarian families.•Unstable root topology questions ordinal classification.•Positive ...relationship of ML support and depth of locus coverage on branches.
Gobies, sleepers, and cardinalfishes represent major clades of a species rich radiation of small bodied, ecologically diverse percomorphs (Gobiaria). Molecular phylogenetics has been crucial to resolving broad relationships of sleepers and gobies (Gobioidei), but the phylogenetic placements of cardinalfishes and nurseryfishes, as reciprocal or sequential sister clades to Gobioidei, are uncertain. In order to evaluate relationships among and within families we used a phylogenetic data mining approach to generate densely sampled trees inclusive of all higher taxa. We utilized conspecific amino acid homology to improve alignment accuracy, included ambiguously identified taxa to increase taxon sampling density, and resampled individual gene alignments to filter rogue sequences before concatenation. This approach yielded the most comprehensive tree yet of Gobiaria, inferred from a sparse (17 percent-complete) supermatrix of one ribosomal and 22 protein coding loci (18,065 characters), comprised of 50 outgroup and 777 ingroup taxa, representing 32 percent of species and 68 percent of genera. Our analyses confirmed the lineage-based classification of gobies with strong support, identified sleeper clades with unforeseen levels of systematic uncertainty, and quantified competing phylogenetic signals that confound resolution of the root topology. We also discovered that multilocus data completeness was related to maximum likelihood branch support, and verified that the phylogenetic uncertainty of shallow relationships observed within goby lineages could largely be explained by supermatrix sparseness. These results demonstrate the potential and limits of publicly available sequence data for producing densely-sampled phylogenetic trees of exceptionally biodiverse groups.
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•Phylogenetic relationships of Gobioidei are inferred based on multilocus data.•A robust, comprehensive phylogenetic hypothesis for Gobioidei is established.•New suprageneric group ...names for the major lineages within Gobiidae are proposed.•Early bursts of cladogenesis of the gobiine-like gobiids are tentatively resolved.•The European gobiid diversity is recovered in three independent lineages.
Gobioidei is one of the largest suborders of teleost fishes, with nearly 2000 extant species currently recognized. They have a worldwide distribution and show a spectacular variety in morphology, ecology, and behavior. Despite their importance, phylogenetic relationships among many groups of gobioids (including some of the major lineages) still remain poorly understood. In this study, we analyze sequence data of five molecular markers (two mitochondrial and three nuclear) averaging 6000bp for 222 species of gobioids. Our study is the first to include both multiple nuclear and mitochondrial genes to reconstruct a comprehensive multilocus phylogeny of gobioids encompassing most major lineages representing the overall diversity of one of the most speciose vertebrate lineages. Two separate datasets are produced and used to specifically address the phylogenetic placement of Rhyacichthyidae and Odontobutidae, and the phylogenetic relationships among gobioid lineages. Our results strongly support that the initial split in the gobioid tree separated a clade containing Rhyacichthyidae+Odontobutidae as the sister group of all other lineages. The family Eleotrididae branches off the gobioid tree after the Rhyacichthyidae+Odontobutidae clade, followed by the Butidae as sister group to the Gobiidae. Additionally, several major monophyletic groups are confidently identified within the two major Gobiidae subclades, the gobiine-like gobiids and the gobionelline-like gobiids. Robustness of the phylogenetic trees inferred here is significantly higher than that of previous studies, hence our results provide the most compelling molecular phylogenetic hypothesis of Gobioidei thus far. For the first time, we provide a comprehensive sampling of European gobies that traditionally have been divided into “transverse” gobies and “sand gobies". We show that the European gobies cluster in three distinct lineages, the Pomatoschistus-, Aphia-, and Gobius-lineages. The former resolved within the gobionelline-like gobiids and the latter two within the gobiine-like gobiids. These findings have significant implications for our understanding of the phylogeographic origin of European gobies in the light of the closure of the Paratethys. A rogue taxon analysis identified Kraemeria as an unstable taxon decreasing support at the base of the gobiine-like gobiids. Removal of this rogue taxon significantly increased phylogenetic resolution in that part of the tree and revealed additional insights into early bursts of cladogenesis of the gobiine-like gobiids.
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•The most extreme specializations to terrestriality evolved twice.•Intermediate morphologies are independent adaptions to living in mud or the water margin, rather than transitional ...forms.•Oxudercinae (mudskippers) and Amblyopinae (eel gobies) are reciprocally paraphyletic; Oxudercinae is a junior synonym.
The initial vertebrate conquest of land by stegocephalians (Sarcopterygia) allowed access to new resources and exploitation of untapped niches precipitating a major phylogenetic diversification. However, a paucity of fossils has left considerable uncertainties about phylogenetic relationships and the eco-morphological stages in this key transition in Earth history. Among extant actinopterygians, three genera of mudskippers (Gobiidae: Oxudercinae), Boleophthalmus, Periophthalmus and Periophthalmodon are the most terrestrialized, with vertebral, appendicular, locomotory, respiratory, and epithelial specializations enabling overland excursions up to 14 h. Unlike early stegocephalians, the ecologies and morphologies of the 45 species of oxudercines are well known, making them viable analogs for the initial vertebrate conquest of land. Nevertheless, they have received little phylogenetic attention. We compiled the largest molecular dataset to date, with 29 oxudercine species, and 5 nuclear and mitochondrial loci. Phylogenetic and comparative analyses revealed strong support for two independent terrestrial transitions, and a complex suit of ecomorphological forms in estuarine environments. Furthermore, neither Oxudercinae nor their presumed sister-group the eel gobies (Amblyopinae, a group of elongated gobies) were monophyletic with respect to each other, requiring a merging of these two subfamilies and revealing an expansion of phenotypic variation within the “mudskipper” clade. We did not find support for the expected linear model of ecomorphological and locomotory transition from fully aquatic, to mudswimming, to pectoral-aided mudswimming, to lobe-finned terrestrial locomotion proposed by earlier morphological studies. This high degree of convergent or parallel transitions to terrestriality, and apparent divergent directions of estuarine adaptation, promises even greater potential for this clade to illuminate the conquest of land. Future work should focus on these less-studied species with “transitional” and other mud-habitat specializations to fully resolve the dynamics of this diversification.
Morphological characters, such as body shape, morphometric measurements and meristic counts, have long been used in stock identification. Round goby (Neogobius melanostomus), of the family Gobiidae, ...is a benthic euryhaline species that is native to central Eurasia. Round goby invasion has had detrimental effects on native fish species and it is included in the list of 100 worst European invasive species. To the best of our knowledge, no previous studies had investigated the morphometric characterization of this species in the region, so the present study aims to give information about the morphometric characteristics of N. melanostomus in the coast of Ordu (Eastern Black Sea). A total of 16 morphological characters were measured using a caliper to the nearest ±0.001 cm. For the subsequent statistical procedures, the ratio of relative morphometric characters to total length (TB) was used. The samples examined were divided into three length groups: group I (10-14.9 cm; 18 samples), group II (15-19.9 cm; 26 samples) and group III (20-24.9 cm; 17 samples). With respect to coefficient of variation, first dorsal fin base length (D1T) was determined as the most variable character, whereas eye diameter (GÇ) was determined as the least variable character. Statistically significant correlations between POU, PA, BD2, D1T, D2T, PU, MxVY, KSY, and TB% were observed (P<0.05). Linear regression values indicated that, while standard length and total length had highest correlation (r=0.998), preorbital distance and total length had lowest correlation values (r=0.830).
Anthropogenic noise is a global pollutant but its potential impacts on early life-stages in fishes are largely unknown. Here, using controlled laboratory experiments, we tested for impacts of ...continuous or intermittent exposure to low-frequency broadband noise on early life-stages of the common goby (Pomatoschistus microps), a marine fish with exclusive paternal care. Neither continuous nor intermittent noise exposure had an effect on filial cannibalism, showing that males were capable and willing to care for their broods. However, broods reared in continuous noise covered a smaller area and contained fewer eggs than control broods. Moreover, although developmental rate was the same in all treatments, larvae reared by males in continuous noise had, on average, a smaller yolk sac at hatching than those reared in the intermittent noise and control treatments, while larvae body length did not differ. Thus, it appears that the increased consumption of the yolk sac reserve was not utilised for increased growth. This suggests that exposure to noise in early life-stages affects fitness-related traits of surviving offspring, given the crucial importance of the yolk sac reserve during the early life of pelagic larvae. More broadly, our findings highlight the wide-ranging impacts of anthropogenic noise on aquatic wildlife living in an increasingly noisy world.
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•Noise exposure during early life-stages affects fitness-related traits in fish.•Noise exposure decreases the yolk sac reserve during early life of pelagic larvae.•Brood size, brood area, and egg density decreased with increased noise.•Noise pollution had a negative effect on egg and larval development.•Highlights the wide-ranging impacts of anthropogenic noise on aquatic wildlife
Lay Summary The behavior of individuals of an invasive species may differ according to where they live relative to an expansion front. Tests in an artificial channel demonstrated that round goby from ...an invasion front left a shelter sooner, dispersed farther and faster, and had higher RMRs than those from the same river, but distant from the expanding front. These results suggest that the location, activity, and physiology of bold individuals facilitate range expansion of an invasive species.The successful establishment and expansion of invasive species may be linked to the behavior and dispersal tendency of individuals within an introduced population. To test the prediction that the boldest individuals, with the greatest dispersal tendency would be concentrated in the area of active range expansion, we compared the behavior, dispersal tendency, and metabolic rate of male round goby (Neogobius melanostomus) sampled from the expanding edge of their range with those sampled from an established area in the Trent-Severn Waterway, Ontario, Canada. Behavior and dispersal tendency were assessed in an artificial flume at 2 different water velocities using individuals caught in the spring and autumn of 2013, while resting metabolic rate (RMR) was determined using intermittent flow-through respirometry on fish collected in the autumn only. Round goby from the edge of their expanding range emerged from a shelter sooner, moved farther and faster in the flume, and had higher RMRs than individuals from established areas within the river. Neither water velocity nor season of capture was important in explaining the variation in time of emergence or movement. The higher proportion of bold individuals with high dispersal potential at invasion fronts facilitates further dispersal of round goby populations, and could help explain the rapid expansion of this species in North America and Western Europe. However, the benefits of bold phenotypes in terms of dispersal may be offset by increased energetic costs while at rest.
Hypoxia-inducible factor-1alpha (HIF-1alpha) plays a critical role in immune and inflammatory responses and is important in controlling a variety of processes in monocytes and macrophages. However, ...very little information is available about the functions of HIF-1alpha in fish monocytes/macrophages (MO/MPHI). In this study, the cDNA sequence of the mudskipper (Boleophthalmus pectinirostris) HIF-1alpha gene (BpHIF-1alpha) was determined. Sequence comparison and phylogenetic tree analysis showed that BpHIF-1alpha is clustered in the fish HIF-1alpha tree. Constitutive expression of BpHIF-1alpha mRNA was detected by real-time quantitative PCR in all tested tissues, and the expression was found to be dramatically increased in the skin, liver, spleen, and kidney after Edwardsiella tarda infection. In addition, hypoxia and infection induced the expression of the BpHIF-1alpha transcript and protein in MO/MPHI, respectively. Hypoxia caused an increase in phagocytic and bactericidal capacity of mudskipper MO/MPHI in a BpHIF-1alpha-dependent manner. BpHIF-1alpha induced an anti-inflammatory status in MO/MPHI upon E. tarda infection and hypoxia. Therefore, BpHIF-1alpha may play a predominant role in the modulation of mudskipper MO/MPHI function in the innate immune system.
A major goal of the aquaculture industry is to reduce collection pressure on wild populations by developing captive breeding techniques for marine ornamental species, particularly coral reef fishes. ...The objective of this study was to develop a rearing protocol for two recently described species of neon gobies that are endemic to the Mesoamerican Barrier Reef: 1) Elacatinus lori; and 2) Elacatinus colini. First, the current study describes the reproductive behavior and larval development of both species. Second, it evaluates the effects of different rotifer and Artemia densities on the survival and growth of E. lori and E. colini larvae. Third, it compares the survival and growth of E. colini larvae fed wild plankton to those fed a combination of rotifers and Artemia. Once acclimated, pairs of E. lori began spawning in 53.2±12.4 d (mean±sd), while pairs of E. colini took only 12.2±10.3 d. E. lori produced more embryos per clutch (1009±477) than E. colini (168±83). E. lori larvae hatched 8.18±0.4days after initial observation with a notochord length of 3.67±0.2mm. In comparison, E. colini larvae hatched 6.8±0.4days after initial observation with a notochord length of 3.51±2.3mm. Both species settled as early as 28days post hatch at 9–9.5mm standard length, following the fusion of the pelvic fins to form a pelvic disc. During rotifer density trials, from 0 to 6days post hatch, there was no significant difference in survival or standard length between treatments fed 10, 15 or 20rotifersml−1 for either species. During Artemia density trials, from 6 to 14days post hatch, control treatments fed solely on 15rotifersml−1 had significantly higher survival than treatments that were fed rotifers in combination with 3, 6 or 9Artemiaml−1. Finally, E. colini larvae that were fed wild plankton had significantly higher survival and growth than those fed with a combination of 15rotifersml−1 and 3Artemiaml−1. The results of this study suggest that Artemia nauplii are not a suitable prey for E. lori or E. colini larvae. Our results demonstrate the feasibility of rearing E. lori and E. colini to settlement, and suggest that 10–20rotifersml−1 and wild plankton provide a viable starting point for optimizing the survival and growth of Elacatinus spp. larvae.
•A description of reproductive behavior and a larval rearing protocol are provided for two species of Elacatinus gobies.•There was no difference in the survival or standard length of larvae that were fed 10, 15 or 20rotifers ml−1.•Larvae fed Artemia beginning at 6days post hatch had lower survival than controls fed solely with rotifers.•E. colini larvae fed wild plankton had higher survival and growth than those fed a combination of rotifers and Artemia.•A diet of 10 – 20rotifers ml−1 and wild plankton provides a viable starting point for rearing Elacatinus spp. larvae.
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