Desert pumpkinseed: diet composition and breadth in a Moroccan river

The widely invasive North American pumpkinseed sunfish, Lepomis gibbosus, is currently established in desert rivers in Morocco. The success of pumpkinseed in novel ecosystems has been associated with its generalist diet, but this trait remains unevaluated in arid regions. Desert rivers are harsh environments with limited water and prey availability which may adversely constrain the diet of fish. Here we studied the diet of pumpkinseed across 4 sites in the Draa River, embracing a 450 m elevational gradient covering from extremely dry lowlands to relatively humid highlands. We described pumpkinseed diet through the analysis of stomach contents of 82 individuals, collected in the fall of 2013. Pumpkinseed diet was dominated by Chironomidae in dry lowlands, while Ephemeroptera, Heteroptera, Trichoptera and Odonata were relevant prey in more humid highlands. Population diet breadth expanded with elevation, but individual specialization in diet was low among all sites. Our results highlight considerable changes in diet composition and breadth with aridity, suggesting that feeding plasticity and use of exclusive, locally abundant prey rather than generalized feeding may be associated with the success of pumpkinseed in most arid areas in desert rivers.info:eu-repo/semantics/publishedVersio

Dietary niche divergence between two invasive fish in Mediterranean streams

Clarifying the mechanisms associated with the coexistence of invasive species is important to understand the overall impact of multiple invasions on recipient communities. Here we examined whether divergence or convergence in dietary niche occurred when invasive Lepomis gibbosus and Australoheros facetus coexist in Iberian streams. We used stomach content analyses to determine dietary niche composition, width, and overlap in allopatric and sympatric counterparts in the Lower Guadiana throughout the dry-season. The variations in dietary niche between pumpkinseed and the cichlid were consistent with predictions derived from the niche divergence hypothesis. Although there were no changes in the use of plant material from allopatry to sympatry in either species, sympatric pumpkinseed and the cichlid displayed marked shifts in the use of animal prey and a decrease in niche width relative to allopatric counterparts. Moreover, sympatric pumpkinseed and cichlid showed similar niche width but differed significantly in plant and animal prey use. Taken together these results suggest that divergence in dietary niches may play a role in mediating coexistence of multiple invaders in Iberian streams

Historical food-web changes in invaded fish communities in the lower Guadiana basin

Freshwater ecosystems are increasingly being reshaped by biological invasions, leading to biotic homogenization and biodiversity loss. However, the extent to which novel species may drive changes in food-web structure over time remains poorly understood. Clarifying changes in historical ecological processes is critical to inform conservation and restoration efforts in recipient ecosystems. Here, we address food-web changes associated with fish invasions in the Lower Guadiana Basin (LGB) over the past 40 years, by contrasting feeding relationships between museum-archived and contemporary specimens, using stable carbon (δ13C) and nitrogen (δ15N) ratios. Specifically, trophic niches of museum-archived fishes sampled throughout 1978–1987 and 1999–2004 corresponding to the initial establishment and spread of non-native fishes, respectively, were compared with those of fishes sampled in 2019, characterizing the integration of non-native species in the recipient ecosystem. We focused on five native species (Anaecypris hispanica, Cobitis paludica, Iberochondrostoma lemmingii, Squalius pyrenaicus and Squalius alburnoides) and four non-native species (Lepomis gibbosus, Australo heros facetus, Micropterus salmoides and Gambusia holbrooki) with potential to cover multiple trophic positions in the food-webs. We approached historical baseline resources using prey items in gut con tents of the museum-archived fishes and characterized primary producers and macroinvertebrates in 2019. Prior to analysis, samples were normalized for high lipid content and corrected for preservation. We found considerable asymmetries in niche partitioning among species as invasion progressed. Over time, native species tended to be displaced to lower trophic levels, while non-native species showed significantly higher trophic niches, driven mainly by increases in trophic (δ15N) range. Our study highlights that stable isotopes may provide important insights on historical food-web structure and particularly on processes underpinning ecological changes associated with anthropogenetic pressures on freshwater ecosystems.info:eu-repo/semantics/publishedVersio

Ecology of Gobiidae species in inland waters of Western Greece with emphasis on species Economidichthys pygmaeus (Holly, 1929) in Lake Pamvotis

Until now, there are a limited number of studies about life-history strategies and the phylogenetic studies of endemic gobies in Greece. Based on the above considerations, the present doctorate thesis investigates the ecology of the endemic Economidichthys pygmaeus and the phylogenetic relationships of ‘sand gobies’ through morphometric variability and the use of molecular marker COI. A total of 1.698 specimens of E. pygmaeus were captured of which 356 were males, 480 were females and 862 were immature individuals. Μales reached higher length than females while juveniles made their appearance during spring. The growth of the goby was positively allometric for both sexes (b>3). The total sex ratio differed significantly from the theoretical value 1:1. The spawning period of E. pygmaeus in lake Pamvotis began in March to May. E. pygmaeus is an omnivorous fish which preys on copepods and chironomidae larvae. Cladocerans, gastropods and insects had less participation on diet. Under the frame of reproductive behavior, the lack of sound production was recorded between the male-male interactions of E. pygmaeus and during the courtship and spawning phases. The sound production from the rest of the ‘sand gobies’ implied that sound is an ancestral trait which E. pygmaeus lost secondarily. The morphometric analysis was performed on meristic characters and on 33 morphometric variables. Principal Component Analysis (PCA) demonstrated a difference in length of first dorsal and anal fin and the size of the head among species whereas Discriminant Analysis (DA) supported a clear discrimination of ‘sand gobies’. Cluster analysis showed a characteristic geographic pattern. The results showed that these phylogenetic methods agree with the systematic classification of genus Economidichthys through the clustering of E. pygmaeus and E. trichonis. The split-up of K. caucasica populations from the Ionian Sea including K. milleri with the K. caucasica populations from the Aegean Sea demonstrate the paraphyletic problem. Finally, the genus Pomatoschistus is divided into three monophyletic clades corresponding to the species P. minutus, P. marmoratus and P canestrinii.Μέχρι σήμερα υπάρχει περιορισμένος αριθμός μελετών για τις βιολογικές στρατηγικές και τη φυλογένεση των ενδημικών γωβιών στον ελλαδικό χώρο. Με βάση τα παραπάνω, η παρούσα έρευνα εξετάζει την οικολογία του ενδημικού είδους Economidichthys pygmaeus καθώς και τις φυλογενετικές σχέσεις των ‘αμμογωβιών’ διαμέσου της μορφολογικής ποικιλομορφίας και του μοριακού δείκτη COI. Συλλέχθηκαν συνολικά 1.698 άτομα του είδους E. pygmaeus, από τα οποία 356 ήταν αρσενικά, 480 θηλυκά και 862 ανώριμα. Τα αρσενικά φτάνουν σε μεγαλύτερο μήκος από τα θηλυκά, ενώ η είσοδος των νεαρών ατόμων πραγματοποιείται την άνοιξη. Η αύξηση του λουρογωβιού ήταν θετικά αλλομετρική και για τα δύο φύλα (b>3). Η συνολική αναλογία φύλων διέφερε στατιστικά από τη θεωρητική τιμή 1:1. Η αναπαραγωγική περίοδος του E. pygmaeus στη λίμνη Παμβώτιδα διαρκεί από το Μάρτιο ώς το Μάιο. Πρόκειται για ένα παμφάγο είδος που θηρεύει κυρίως κωπήποδα και προνύμφες χειρονομίδων. Μικρότερη συμμετοχή είχαν τα κλαδόκερα, γαστερόποδα και τα έντομα. Στο πλαίσιο της μελέτης της αναπαραγωγικής συμπεριφοράς καταγράφηκε η απουσία ήχων μεταξύ των αλληλεπιδράσεων των αρσενικών ατόμων του E. pygmaeus και κατά τις φάσεις της ερωτοτροπίας και ωοτοκίας. Η παραγωγή ήχων από τους υπόλοιπους ‘αμμογωβιούς’ υποδηλώνει ότι ο ήχος είναι ένα προγονικό χαρακτηριστικό που χάθηκε δευτερογενώς για το E. pygmaeus. Η εφαρμογή της μορφομετρικής ανάλυσης έγινε με τη μέτρηση των μεριστικών χαρακτήρων και 33 μορφομετρικών μεταβλητών. Η ανάλυση των κύριων συνιστωσών έδειξε πως τα είδη διαφέρουν ανάλογα με το μήκος του 1ου ραχιαίου και του εδρικού πτερυγίου και του μεγέθους της κεφαλής ενώ η διαχωριστική ανάλυση υποστήριξε τη σαφή διάκριση των ειδών της ομάδας ‘αμμογωβιοί’. Η ανάλυση συστοιχειών υπέδειξε την ύπαρξη γεωγραφικού προτύπου. Τα αποτελέσματα που προέκυψαν από την εφαρμογή των φυλογενετικών μεθόδων επιβεβαίωσαν τη συστηματική κατάταξη του γένους Economidichthys με την ομαδοποίηση των E. pygmaeus και E. trichonis. Ο διαχωρισμός των πληθυσμών του K. caucasica από το Ιόνιο Πέλαγος με την ενσωμάτωση του K. milleri από τα δείγματα του K. caucasica από το Αιγαίο Πέλαγος αναδεικνύει το πρόβλημα παραφυλετικότητας. Τέλος, για το γένος Pomatoschistus υποδεικνύεται η ύπαρξη τριών μονοφυλετικών κλάδων που αντιστοιχούν στα είδη P. minutus, P. marmoratus και P canestrinii

SandgobieslandmarksFixedFresh

Landmark data for six species of sand gobies, paired fixed and fresh specimen

Predicting establishment of non-native fishes in Greece: identifying key features <br />

Non-native fishes are known to cause economic damage to human society and are considered a major threat to biodiversity loss in freshwater ecosystems. The growing concern about these impacts has driven to an investigation of the biological traits that facilitate the establishment of non-native fish. However, invalid assessment in choosing the appropriate statistical model can lead researchers to ambiguous conclusions. Here, we present a comprehensive comparison of traditional and alternative statistical methods for predicting fish invasions using logistic regression, classification trees, multicorrespondence analysis and random forest analysis to determine characteristics of successful and failed non-native fishes in Hellenic Peninsula through establishment. We defined fifteen categorical predictor variables with biological relevance and measures of human interest. Our study showed that accuracy differed according to the model and the number of factors considered. Among all the models tested, random forest and logistic regression performed best, although all approaches predicted non-native fish establishment with moderate to excellent results. Detailed evaluation among the models corresponded with differences in variables importance, with three biological variables (parental care, distance from nearest native source and maximum size) and two variables of human interest (prior invasion success and propagule pressure) being important in predicting establishment. The analyzed statistical methods presented have a high predictive power and can be used as a risk assessment tool to prevent future freshwater fish invasions in this region with an imperiled fish fauna

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Alignment of partial COI sequences for sand goby phylogen

SandGobiescalibratedphylogeny

Calibrated phylogeny of reduced set of sand gobie

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Bayesian phylogeny of partial COI sequences for sand gobie

Data from: Morphometric convergence among European sand gobies in freshwater (Gobiiformes: Gobionellidae)

The five genera of sand gobies inhabit the seas and freshwaters of Europe and western Asia and occupy habitats ranging from fully marine to exclusively freshwater. In this study, we use geometric morphometrics to quantify body shape among sand gobies, in order to investigate how shape has evolved and how it is related to habitat. We also compare body shape between preserved museum specimens and fresh specimens, to determine whether or not fixation and storage in ethanol introduces detectable bias. We confirm that the fixed specimens exhibit significant shape changes as compared to fresh specimens, and so we perform the bulk of our analyses exclusively on fixed specimens. We find that Economidichthys, Orsinigobius, and Pomatoschistus occupy distinct regions of morphospace. Knipowitschia and Ninnigobius have intermediate forms that overlap with Pomatoschistus and Orsinigobius, but not Economidichthys. This pattern is also in rough accordance with their habitats: Pomatoschistus is fully marine, Economidichthys fully freshwater, and the others fresh with some brackish tolerance. We augment a recent phylogeny of sand gobies with data for P. quagga, and interpret morphometric shape change on that tree. We then evaluate convergence in form among disparate lineages of freshwater species by constructing a phylomorphospace, and applying pattern-based (convevol) measures of convergence. We find that freshwater taxa occupy a mostly separate region of morphospace from marine taxa, and exhibit significant convergence in form. Freshwater taxa are characterized by relatively larger heads and stockier bodies than their marine relatives, potentially due to a common pattern of heterochronic size reduction