A handy note on the basic taxonomic features of five <i>Schizothorax</i> species of Kashmir Himalaya, India

Across its Holarctic range, Arctic charr (Salvelinus alpinus) populations have diverged into distinct trophic specialists across independent replicate lakes. The major aspect of divergence between ecomorphs is in head shape and body shape, which are ecomorphological traits reflecting niche use. However, whether the genomic underpinnings of these parallel divergences are consistent across replicates was unknown but key for resolving the substrate of parallel evolution. We investigated the genomic basis of head shape and body shape morphology across four benthivore-planktivore ecomorph pairs of Arctic charr in Scotland. Through genome-wide association analyses, we found genomic regions associated with head shape (89 SNPs) or body shape (180 SNPs) separately and 50 of these SNPs were strongly associated with both body and head shape morphology. For each trait separately, only a small number of SNPs were shared across all ecomorph pairs (3 SNPs for head shape and 10 SNPs for body shape). Signs of selection on the associated genomic regions varied across pairs, consistent with evolutionary demography differing considerably across lakes. Using a comprehensive database of salmonid QTLs newly augmented and mapped to a charr genome, we found several of the head- and body-shape-associated SNPs were within or near morphology QTLs from other salmonid species, reflecting a shared genetic basis for these phenotypes across species. Overall, our results demonstrate how parallel ecotype divergences can have both population-specific and deeply shared genomic underpinnings across replicates, influenced by differences in their environments and demographic histories.

Schizothorax lissolabiatus and Schizothorax griseus are native Chinese fish species with significant ecological and economic importance. We wanted to support sustainable aquaculture practices by exploring the differences in metabolic, histological, and microbiota between the two Schizothorax species. This study analyzed and compared the digestive enzyme activities, metabolic indicators, gut histology, and microbiota composition of S. lissolabiatus and S. griseus under identical farming conditions. Our comparative analysis reveals both shared characteristics and species-specific differences. While a-amylase and trypsin activities showed no significant differences between species, a consistent trend was observed, with enzyme activity highest in the hindgut, followed by the midgut, foregut, esophagus, and liver. In terms of specific metabolic markers, S. griseus shows higher lipase activity in the liver and foregut, as well as higher aspartate aminotransferase and catalase levels in the liver, along with an increased serum glucose content compared to S. lissolabiatus. Serum metabolomics analysis revealed 21 differentially abundant metabolites linked to glycerophospholipid metabolism, autophagy, purine metabolism, and necroptosis, reflecting distinct metabolic adaptations and nutritional needs for each species. These metabolic differences provide a basis for optimizing feed composition and aquaculture practices tailored to each species. Notably, S. lissolabiatus displays a significantly higher goblet cell count in the hindgut compared to S. griseus. Additionally, both species exhibit greater villi number, length, width, crypt depth, and muscle thickness in the esophagus than in the foregut, midgut, and hindgut. S. griseus also has a higher number of operational taxonomic units (OTUs) and greater microbial diversity in its intestinal microbiota, which may enhance its nutrient utilization capabilities. While both species’ dominant microbial phyla include Fusobacteria, Firmicutes, Proteobacteria, and Bacteroidetes, S. griseus demonstrated superior lipid digestion capabilities. Furthermore, the midgut and hindgut in both species display higher starch and protein digestive enzyme activities than other digestive tissues. These findings highlight the physiological differences between the two Schizothorax species, suggesting targeted strategies to improve health, growth, and sustainability in aquaculture.

It is well recognized that environmental degradation caused by human activities can result in dramatic losses of species and diversity. However, comparatively little is known about the ability of biodiversity to re-emerge following ecosystem recovery. Here, we show that a European whitefish subspecies, the gangfisch Coregonus lavaretus macrophthalmus, rapidly increased its ecologically functional diversity following the restoration of Lake Constance after anthropogenic eutrophication. In fewer than ten generations, gangfisch evolved a greater range of gill raker numbers (GRNs) to utilize a broader ecological niche. A sparse genetic architecture underlies this variation in GRN. Several co-expressed gene modules and genes showing signals of positive selection were associated with GRN and body shape. These were enriched for biological pathways related to trophic niche expansion in fishes. Our findings demonstrate the potential of functional diversity to expand following habitat restoration, given a fortuitous combination of genetic architecture, genetic diversity and selection.

Fish blood is a pathophysiological indicator of the whole body function and is thus considered as an important tool in diagnosing the structural and functional status of fish. However, the blood parameters vary between species to species and it mainly depends upon the favorable environmental conditions where the species live. The purpose of the current study is to evaluate the hematological and serum biochemical indices of five Schizothorax species: Schizothorax labiatus, S. plagiostomus, S. esocinus, S. curvifrons and S. niger in order to establish the resemblances and variations between these Schizothorax species which are inhabiting in river Jhelum. The hematological profile including hemoglobin (Hb), total red blood cell (RBC) count, hematocrit (Hct), white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and erythrocyte indices: mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and mean corpuscular volume (MCV) was analyzed from each Schizothorax sp. Statistical analysis showed that there were significant differences (p < 0.05) in blood parameters among five Schizothorax spp. The results showed lowest values of hematological parameters in S. niger with respect to other species, while the highest values of hematological parameters were recorded in S. plagiostomus. Significant differences (p < 0.05) in serum biochemical levels of glucose, protein, cholesterol and urea were also noted in Schizothorax spp. The differences found in the hematological profile and serum biochemical composition in these fishes can be attributed to the individual feeding behavior, tolerance and environmentally adjustable capability of the fish. However, further study is required to correlate the present study with some other parameters such as the nutrient status of the river Jhelum where these fishes live.

Northern freshwater fi shes, particularly members of the genus Coregonus, have been used as a model for studying microevolution due to their well known colonization history coupled with parallel patterns of phenotypic differentiation. We assessed and described the phenotypic diversity among ciscoes in the Yellowknife Bay region of Great Slave Lake using 1) traditional taxonomic methods for cisco species and 2) contemporary linear and geometric morphometric methods. Four morphs were identifi ed using a qualitative visual assessment of gross morphology and/or location of capture in comparison to published taxonomy for the genus Coregonus. The morphs identifi ed were assigned the following colloquial names: A) 'adfl uvial', B) 'lacustrine', C) 'shortjaw', and D) 'least'. Univariate analyses on taxonomic measures indicated that cisco varied in terms of age, number of lateral line scales, number of anal fi n rays, middle gill raker length, and lower gill arch length. By contrast, fi ve morphs were identifi ed using cluster analysis of linear and geometric morphometric data combined with age and gill raker number. The additional phenotypic cluster entailed a splitting of large and small lacustrine morphs into two groups. Multivariate analyses indicated a strong relationship between body shape and gill raker number, eye size, age and mouth morphology. These results suggested that the segregation among morphs was based on differential usage of trophic and/or habitat resources as well as life history variation such as age at maturity. Our results indicated that the level of phenotypic diversity was greater than previously documented for Great Slave Lake and that this diversity was similar to that reported for ciscoes in the Laurentian Great Lakes.

The genus Sorubim Cuvier, 1829, and two species, S. lima (Bloch &amp; Schneider 1801) and S. trigonocephalus Miranda- Ribeiro, 1920, are redescribed based on the examination of type material and about 400 non-type specimens from ichthyological collections in Europe and North and South America. The five species of the genus are, in addition to S. lima and S. trigonocephalus, S. elongatus Littmann, Burr, Schmidt and Isern 2001, found in the Essequibo, Orinoco, and Amazon basins; S. cuspicaudus Littmann, Burr and Nass 2000, occurring in the Sinu, Cauca, and Magdalena rivers of Colombia and the Lago Maracaibo basin of Colombia and Venezuela; and S. maniradii Littmann, Burr and Buitrago-Suarez 2001, known from the upper and middle Amazon basin. Sorubim lima is the widest-ranging species, occurring in most of the major drainage basins of South America. Sorubim trigonocephalus is extremely rare in natural history collections and is currently known from only two major tributaries of the Amazon basin. Three species (S. maniradii, S. elongatus, and S. lima) occur syntopically. Species of Sorubim are diagnosed on the basis of body and head shape, differences in fin ray and gill-raker numbers, mental barbel position, and degree of pigmentation of the lateral stripe. At least two of the species (S. lima and S elongatus) make up part of the ornamental fish trade and are sold for food in local fish markets in South America. A key to adults of the five species is included.

The taxonomy of the North American ciscoes (Salmoniformes: Coregonidae) remains unresolved. We provide the first comprehensive description of the Great Slave Lake ciscoes. Our analysis supports the hypothesis that the Great Slave Lake cisco complex includes at least two nominate species (Coregonus artedi and Coregonus sardinella) and an adfluvial C. artedi morph that is distinct from its lacustrine conspecific in terms of life history, morphology, age, growth and mortality. Coregonus sardinella has previously been identified from Great Slave Lake, but we provide the first comprehensive description of this species in the lake and confirm a significant range extension for the species. The lacustrine C. artedi differs little from descriptions throughout its range. In addition to these three ciscoes, linear phenotypic traits, gillraker number and morphology, and growth data support the possible occurrence of two other, less‐distinct morphs, the big‐eye cisco and a shortjaw‐like morph Coregonus zenithicus. Although the big‐eye morph was not identified by body shape and linear phenotypic measures, it was visually identified on the basis of differences in traditional phenotypic proportions, such as orbital length, paired fin lengths, head and gillraker morphology expressed as thousands of standard length and showed different age and growth structure compared with the other lacustrine cisco morphs. Coregonus zenithicus was distinguished visually and by a statistical model of linear phenotypic traits as well as by gillraker number and morphology. Identifying, characterising and managing locally adapted cisco morphs that reflect important ecological and bioenergetic linkages are critical to conserving the ecological integrity of northern ecosystems.

AimInvasive species have the potential to alter hydrological processes by changing the local water balance. However, general patterns of how rainfall is partitioned into interception, throughfall and stemflow for invasive species worldwide have been seldom explored. We (a) describe the percentage of interception, throughfall and stemflow for invasive woody plant species; (b) analyse the influence of morphological attributes (i.e. life‐form, bark roughness, leaf type, leaf phenology and leaf area index) of invasive species on rainfall partitioning; and (c) compare the rainfall partitioning fluxes for co‐occurring invasive and native species, testing whether the variation in these fluxes depends on water availability of the study location.LocationGlobal.Time periodPresent.Major taxa studiedPlants.MethodsWe compiled data of 100 studies that assessed rainfall partitioning by invasive species (n = 67) and registered their morphological attributes. By means of a meta‐analysis we compared the rainfall partitioning by native and invasive species (n = 47 comparisons) and assessed how their fluxes were affected by water availability.ResultsInterception, throughfall and stemflow ranged from 1.6–59.5, 39.1–92.7 and 0.1–31.6% of total rainfall, respectively. The bark roughness and leaf type were the most important attributes driving rainfall partitioning fluxes. While rough‐barked species constrain rainfall inputs by promoting higher losses due to interception, smooth‐barked species with broad leaves enhance the amount of rainwater reaching the soil by maximizing stemflow. For pairwise comparisons, invasive species have higher stemflow values than native species for both drylands and humid areas, and higher throughfall in drylands, but less in humid areas.Main conclusionsOur findings suggest that specific morphological attributes of invasive species determine higher localized water inputs, which may represent an ecohydrological advantage, particularly in water‐limited ecosystems. These insights also suggest that the ecological role of stemflow, throughfall and interception should be considered in future plant invasions research.

Morphological variations among Schizothorax species from Kashmir Himalayas

Five new species of the Neotropical characiform genus Astyanax Baird & Girard are described from Rio Iguaçu at the border of Paraná and Santa Catarina states, southeastern Brazil and Astyanax gymnogenis Eigenmann is redescribed. Each new species can be distinguished from all other Astyanax species from the upper Rio Paraná basin by exclusive combinations of: tooth shape, number of dental cuspids, distance between third infraorbital and preopercle, number of lateral line scales, longitudinal series of scales, number of gill-rakers and differences from shape of body and head traits. This study proposes the species of genus Astyanax from Rio Iguaçu as probably endemic, since all of them are absent from tributaries of the Rio Paraná hydrographic system. The high degree of diversification acquired by those Astyanax species in the Iguaçu basin may perhaps be allied to the long isolation period of this river from the Rio Paraná basin caused by the Iguaçu waterfalls. This barrier probably isolated those basins resulting in original groups of Characiformes and then Astyanax species, both isolated from one another and both different from their relatives in neighbouring basins.

Adaptation to ecologically distinct environments can coincide with the emergence of reproductive barriers. The outcome of this process is highly variable and can range along a continuum from weak population differentiation all the way to complete, genome-wide divergence. The factors determining how far diverging taxa will move along this continuum remain poorly understood but are most profitably investigated in taxa under replicate divergence. Here, we explore determinants of progress towards speciation by comparing phenotypic and molecular divergence within young (<150 years) lake-stream stickleback pairs from Central Europe to divergence in older (thousands of years) archetypal lake-stream pairs from Vancouver Island, Canada. We generally find relatively weak divergence in most aspects of foraging morphology (gill raker number, body shape) in the European pairs, although substantial adaptive divergence is seen in gill raker length. Combined with striking overall phenotypic differences between the continents, this argues for genetic and time constraints on adaptive divergence in the European pairs. The European lake-stream pairs also do not display the strong habitat-related differentiation in neutral (microsatellite) markers seen in the Canadian watersheds. This indicates either the lack of strong reproductive barriers owing to weak adaptive divergence, or alternatively that neutral markers are poorly suited for detecting reproductive barriers if these emerge rapidly. Overall, our comparative approach suggests constraints on speciation due to genetic architecture and limited time for divergence. The relative importance of these factors remains to be quantified by future investigation.

Objective The Lake Trout Salvelinus namaycush diversified into multiple morphs in many lakes of northern North America. Four morphs remain in Lake Superior, of many forms that arose since the most recent glaciation of North America. Our objective was to determine if Lake Trout phenotypic diversity was greater within or among four morphs at six geographically distant locations in Lake Superior. Methods Lake Trout were sampled using standardized multi-mesh gill nets in three depth strata at six locations in Lake Superior that were known to have multiple morphs and were assigned to one of four morphs by reconciling statistical (geometric morphometric analysis of head and body shape) and visual (agreement among three experts) assignment rules. The relative importance of morphs, locations, the interaction between morphs and locations, and residual error for describing variation in head and body shape and associated linear traits were compared. Results The same four morphs were present at nearly all locations. Variation in head and body shape, and associated linear characteristics (head depth, preorbital length, body depth, caudal peduncle length, and caudal peduncle depth), was greater among morphs than among locations. This finding supports a hypothesis that Lake Trout morphs were consistent in shape and related linear traits across a large spatial scale within an environmentally diverse large lake, thereby possibly reflecting genetic differences among morphs. In contrast, variation in linear dimensions describing fin lengths, maxillary length, and other linear segments of head and body length was greater among locations than among morphs. This finding suggests that expressions of these morphometric measures was influenced by location-specific abiotic and biotic conditions. Conclusions We conclude that Lake Trout morphs appeared to have a genetic component to their head and body shape and some other linear morphometric characteristics that was differentially expressed in relation to local environmental conditions.

The tenet that ecological adaptation can lead to recurrent ecomorphological trends resulting from repetitive processes has long been a primary topic of investigation in evolutionary ecology. To explore this aspect further, this study provides an analysis of the morphological diversity in chondrostoms (Cyprinidae). This freshwater fish group shows a tendency towards bottom‐feeding specialization, which has led to evolutionary innovations in body and mouth shape traits, which are currently used for the classification of genera. Body, lower lip (LL) and corner ray shape were analysed for nine species in total. Allometric relationships among the three morphometric traits were considered to be responsible for LL shape variability and there was significant covariation between LL and body shape, which reflected habitat use. Smaller and opportunistic‐feeding species inhabiting stream or small‐sized rivers were characterized by a deeper body (increased feeding maneuverability), an arched LL and a terminal mouth position. Conversely, larger and diet‐specialized species were characterized by a fusiform body (increased swimming performance), a straight LL and an inframouth position on an elongated snout (optimized bottom feeding). The results suggest that interspecific mouth shape variability may have originated from two types of ‘deformation’ processes, both leading to a straight mouth shape and acting either jointly or independently. Also, given the plesiomorphic state of several of the species under study, the specialization towards a benthic lifestyle in chondrostoms from different phylogenetic lineages is thought to have occurred repeatedly to overcome a number of functional constraints, including foraging efficiency and swimming performance.

A revised metric for quantifying body shape in vertebrates

A multivariate solution for dealing with patterns of character covariance, when character genotypic covariances are known, has been applied to the organization of trophic morphology among lacustrine populations of the threespine stickleback (Gasterosteus aculeatus). The quantitative genetics governing eight trophic characters were investigated using representative populations from each of three known trophic ecotypes (open-water, littoral, and intermediate) which occur in the same drainage. Character heritabilities (0.19–0.84) were all significant. Estimates of character genetic correlations (−0.65 &lt; rG &lt; 0.85) were obtained and their standard errors were calculated by bootstrapping. Cluster analyses of the genetic correlation matrices defined two character suites, head shape and gill raker structure. Selection gradients between trophic ecotypes indicated that directional selection had operated most strongly on characters related to food size (upper jaw length and gill raker number). These results support the hypothesis that interpopulation variability in trophic morphology is organized as an adaptive response to local selection pressures.