Characterization of Skin Symbiotic Bacteria of Sympatric Amphibians in Southeastern China

The fungal infection called chytridiomycosis,caused by Batrachochytrium dendrobatidis(Bd),has given rise to dramatic declines or extinctions of many amphibian species around the world;however,in Asia,this disease has shown a low zoospore load or scant mortality.One potential reason for this may be that certain unique community structures of amphibian skin symbiosis contribute to the outcome of the disease;nevertheless,we know very little about the microbiota in this region. In this study,we used skin swabs of five sympatric amphibian species that have various habitat preferences in Lishui,Zhejiang Province,a place in southeastern China,to explore the skin bacterial communities by using 16 S rRNA amplicon sequencing.We detected a total of 1020 OTUs,belonging to 17 phyla,among which Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes dominated all five host species.Enterobacteriaceae and Exiguobacteraceae and the genera Escherichia and Exiguobacterium belonging to these two families were identified as the most abundant taxa on our focal species.The alpha diversity was significantly lower on the terrestrial species,and also the highly enriched Proteobacteria was found on the terrestrial species,Rana zhenhaiensis,whereas Actinobacteria,Bacteroidetes,Cyanobacteria and Firmicutes were more abundant on aquatic species than on the terrestrial species.Our results suggest that both host species and habitat sites are important factors driving skin microbial diversity and composition and that amphibians in China may harbour unique skin bacterial communities.This study helps elucidate amphibian skin microbial ecology,and with further efforts,the specific mechanism of the interaction between Bd and host amphibians in China could be elucidated.

Feeding Ecology and Establishment of the Naturally-Colonized Freshwater Cichlid, Sarotherodon galilaeus (Pisces: Actinopterigii: Perciformes) from a Man-Made Lake, South-Benin, West Africa

The freshwater cichlid, Sarotherodon galilaeus (Linné, 1758) is an economically and commercially important fisheries species that has naturally colonized and dominated a sand-dragged man-made freshwater lake of Ahozon (South-Benin) where the species made about 85.21% of the fish community. We investigated the feeding ecology of S. galilaeus in order to evaluate resource exploitation and the establishment of this species in Lake Ahozon. During wet, flood and dry seasons, 1189 individuals of S. galilaeus have been monthly sampled in the open water and in the aquatic vegetation habitats. The study showed that S. galilaeus consumed about seventy (70) food items dominated by algae (52.88%) composed of 28 families and 52 genera from blue-green algae, green algae, desmids, and diatoms, sand particles (23.95%), detritus (12.27%) and protozoans (7.68%). Minor preys were rotifers, copepods, cladodera, crustacea and insect parts. Foods items with higher diet occurrence were sand particles with a percentage occurrence of 72.33%, detritus (69.47%), and some algae such as Scenedesmus (58.96%), Closterium (55.68%), and Microcystis (51.30%). Significant (P ≤ 0.05) ontogenetic variations of empty stomachs were recorded. S. galilaeus exhibited a wide diet breadth (DB) ranging between 5.55 and 7.29 that tended to increase with fish sizes. Diet overlaps (Øjk) varied from 0.77 to 0.97, indicating high diet similarities between different life stage categories. The slope b = 0.560 obtained from Log (body weight)-Log (gut length) linear regression, and the mean ratio of GL/SL = 6.72 ± 2.23 support our findings that S. galilaeus exhibited detritivorous, herbivorous and omnivorous food habits. The broad spectrum of food resources consumed/utilized and the high diet breadth recorded leading to allometric growth, the active breeding and the high propagation of the species, were some indicators of the successful establishment of S. galilaeus in the man-made lake of Ahozon. Sustainable fisheries/ aquaculture exploitation of S. galilaeus and successful valorization of the man-made lake of Ahozon require an integrated management of the lake including the prevention of domestic waste dumpings, the protection of the foraging and spawning grounds, the fertilization of the lake, the introduction of predators to control the population of S. galilaeus , the protection of lake margin to avoid erosion, a planned harvest of the fish stock and a periodic ecological monitoring of Lake Ahozon.

Anuran forelimb muscle tendinous structures and their relationship with locomotor modes and habitat use

The interaction between organisms and their environment is central in functional morphology.Differences in habitat usage may imply divergent morphology of locomotor systems;thus,detecting which morphological traits are conservative across lineages and which ones vary under environmental pressure is important in evolutionary studies.We studied internal and external morphology in 28 species of Neotropical anurans.Our aim was to determine if internal morphology(muscle and tendons)shows lower phylogenetic signal than external morphology.In addition,we wanted to know if morphology varies in relation to the habitat use and if there are different functional groups.We found differences in the degree of phylogenetic signal on the groups of traits.Interestingly,postaxial regions of the forelimb are evolutionarily more labile than the preaxial regions.Phylomorphospace plots show that arboreal(jumpers and graspers)and swimmer frogs cluster based on length of fingers and the lack of sesamoid,also reflected by the use of habitat.These functional clusters are also related to phylogeny.Sesamoid and flexor plate dimensions together with digit tendons showed to be important to discriminate functional groups as well as use of habitat classification.Our results allow us to identify a"grasping syndrome"in the hand of these frogs,where palmar sesamoid and flexor plate are absent and a third metacarpal with a bony knob are typical.Thus,a lighter skeleton,long fingers and a prensile hand may be key for arboreality.

Geometric morphometrics of mandibles for dietary differentiation of Bovidae(Mammalia:Artiodactyla)

The mammalian family Bovidae has been widely studied in ecomorphological research,with important applications to paleoecological and paleohabitat reconstructions.Most studies of bovid craniomandibular features in relation to diet have used linear measurements.In this study,we conduct landmark-based geometric-morphometric analyses to evaluate whether different dietary groups can be distinguished by mandibular morphology.Our analysis includes data for 100 species of extant bovids,covering all bovid tribes and 2 dietary classifications.For the first classification with 3 feeding categories,we found that browsers(including frugivores),mixed feeders,and grazers are moderately well separated using mandibular shape.A finer dietary classification(frugivore,browser,browser-grazer intermediate,generalist,variable grazer,and obligate grazer)proved to be more useful for differentiating dietary extremes(frugivores and obligate grazers)but performed equally or less well for other groups.Notably,frugivorous bovids,which belong in tribe Cephalophini,have a distinct mandibular shape that is readily distinguished from all other dietary groups,yielding a 100%correct classification rate from jackknife cross-validation.The main differences in mandibular shape found among dietary groups are related to the functional needs of species during forage prehension and mastication.Compared with browsers,both frugivores and grazers have mandibles that are adapted for higher biomechanical demand of chewing.Additionally,frugivore mandibles are adapted for selective cropping.Our results call for more work on the feeding ecology and functional morphology of frugivores and offer an approach for reconstructing the diet of extinct bovids.

Functional diversity of small-mammal postcrania is linked to both substrate preference and body size

Selective pressures favor morphologies that are adapted to distinct ecologies,resulting in trait partition!ng among ecomorphotypes.However,the effects of these selective pressures vary across taxa,especially because morphology is also influenced by factors such as phylogeny,body size,and functional trade-offs.In this study,we examine how these factors impact functional diversification in mammals.It has been proposed that trait partitioning among mammalian ecomorphotypes is less pronoun ced at small body sizes due to biomecha nical,energetic,and environ mental factors that favor a"generalist"body plan,whereas larger taxa exhibit more substantial functional adaptations.We title this the Diverge nee Hypothesis(DH)because it predicts greater morphological divergence among ecomorphotypes at larger body sizes.We test DH by using phylogenetic comparative methods to examine the postcranial skeletons of 129 species of taxonomically diverse,small-tomedium-sized(<15 kg)mammals,which we categorize as either"tree-dwellers"or"ground-dwellers."In some analyses,the morphologies of ground-dwellers and tree-dwellers suggest greater between-group differentiation at larger sizes,providing some evidence for DH.However,this trend is n either particularly strong nor supported by all an alyses.In stead,a more pronoun ced patter n emerges that is distinct from the predictions of DH:within-group phenotypic disparity increases with body size in both ground-dwellers and tree-dwellers,driven by morphological outliers among"medium'-sized mammals.Thus,evolutionary increases in body size are more closely linked to increases in within-locomotor-group disparity tha n to in creases in betwee n-group disparity.We discuss biomechanical and ecological factors that may drive these evolutionary patter ns,and we emphasize the significant evolutionary influences of ecology and body size on phenotypic diversity.

Do key innovations unlock diversification?A case-study on the morphological and ecological impact of pharyngognathy in acanthomorph fishes

Key inn ovations may allow lin eages access to new resources and facilitate the invasi on of new adaptive zon es,potentially influencing diversificati on patter ns.Many studies have focused on the impact of key inno vations on speciation rates,but far less is known about how they influe nee phe notypic rates and patterns of ecomorphological diversification.We use the repeated evolution of pharyngognathy within acanthomorph fishes,a commonly cited key innovation,as a case study to explore the predicti ons of key inn ovation theory.Specifically,we in vestigate whether transiti ons to phary ngognathy led to shifts in the rate of phenotypic evolution,as well as shifts and/or expansion in the occupation of morphological and dietary space,using a dataset of 8 morphological traits measured across 3,853 species of Acanthomorpha.Analyzing the 6 evolutionarily independent pharyngognathous clades together,we found no evidence to support pharyngognathy as a key innovation;however,comparisons between individual pharyngognathous lineages and their sister clades did reveal some consistent patterns.In morphospace,most pharyngognathous clades cluster in areas that correspond to deeper-bodied morphologies relative to their sister clades,whereas occupying greater areas in dietary space that reflects a more diversified diet Additi on ally,both Cichlidae and Labridae exhibited higher univariate rates of phenotypic evolution compared with their closest relatives.However,few of these results were exceptional relative to our null models.Our results suggest that transitions to pharyngognathy may only be advantageous when combined with additional ecological or intrinsic factors,illustrating the importance of account!ng for lineage-specific effects when testing key innovation hypotheses.Moreover,the challenges we experienced formulating informative comparisons,despite the ideal evolutionary scenario of multiple independent evolutionary origins of pharyngognathous clades,illustrates the complexities involved in quantifying the impact of key innovations.Given the issues of lineage specific effects and rate heterogeneity at macroevolutionary scales we observed,we suggest a reassessment of the expected impacts of key innovations may be warranted.