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44 results for “Galaxias”
Genome-wide analysis resolves the radiation of New Zealand's freshwater Galaxias vulgaris complex and reveals a candidate species obscured by mitochondrial capture
<p>Aim: Freshwater fish radiations are often characterized by multiple closely-related species in close proximity, which can lead to introgression and associated discordance of mitochondrial and nuclear characterizations of species diversity. As a case in point, single locus nuclear versus mitochondrial analyses of New Zealand's stream-resident <em>Galaxias vulgaris</em> complex have yielded conflicting phylogenies. Our goal is to use genome-wide divergence patterns among these fishes to evaluate the potential role of mitochondrial capture in obscuring species diversity and to understand how ancient and anthropogenic drainage modification explains this diversity.</p> <p>Location: Freshwater ecosystems of New Zealand. Methods: We generate and analyze a genome-wide data set comprising 52,352 SNPs across 187 <em>Galaxias</em> specimens to resolve the phylogeny of this recent fish radiation. We conduct phylogenetic, PCA, STRUCTURE, and ABBA-BABA analyses to evaluate the evolutionary relationships of lineages in the context of natural and anthropogenic river drainage alterations.</p> <p>Results: In addition to the 11 previously recognized stream-resident lineages, genome-wide data reveal a twelfth candidate species (<em>G</em>. 'Pomahaka'), apparently obscured by introgressive mitochondrial capture. We identify additional examples of mito-nuclear discordance and putative mitochondrial capture, likely mediated by geological and anthropogenic modification of drainage boundaries.</p> <p>Main conclusions: Our study highlights the need for genome-wide approaches for delimiting freshwater biodiversity. Genetic data also reveal the influence of drainage history on freshwater biodiversity, including the rapid divergence of recently fragmented fish populations, and the conservation genetic risks of anthropogenic translocations events.</p>
Figure 2 in Fine-scale abundance variation in New Zealand migratory and non-migratory Galaxias fish species
Figure 2. – Boxplot showing the abundance of migratory (galbre; Galaxias brevipinnis) and non-migratory (galpau; G. paucispondylus and galvul; G. vulgaris) species at sites upstream of lakes (n = 18) and sites without lakes (n = 8). Boxplots show medians (horizontal line), 25th and 75th percentiles (upper and lower box limits), maximum and minimum values (bars), and mean (red dots). Outliers are presented by black circles.
Figure 1 in Fine-scale abundance variation in New Zealand migratory and non-migratory Galaxias fish species
Figure 1. – Map of survey sites, including sites upstream of Lakes Ohau, Pukaki and Tekapo (white boxes), and non-lake stream sites (grey shaded boxes). The number of fish caught at the different sites is shown within the boxes, with Galaxias brevipinnis at the top and non-migratory Galaxias spp. at the bottom of the boxes.
Figure 5 in Fine-scale abundance variation in New Zealand migratory and non-migratory Galaxias fish species
Figure 5. – Principal component analysis (PCA) biplot of the microhabitat environmental factors. Each dot repre- sents one sampling point. The symbols indicate sites upstream of lakes (circles) and sites without lakes (triangles), with the 95% confidence ellipses enclosing sample units from each group. Ellipses that do not overlap represent groups that differ significantly. Dim1, the first PCA axis; Dim2, the second PCA axis.
Figure 5 in Landscape biogeography and population structuring of a facultatively amphidromous galaxiid fish, Galaxias brevipinnis
Figure 5. – Bar plots showing density of Galaxias brevipinnis larvae per m3 of water in plume, near shore, and off shore sites in large river (left) and small river (right) sites. The Dart River, Reese River, Greenstone River, and Buckler Burn are tributaries of Lake Wakatipu while Makarora River, Matukituki River, Boundary Creek, and Albert Burn are tributaries of Lake Wānaka. No larvae were collected in near shore and off shore samples from Greenstone River.
Figure 3. – Average STRUCTURE results aggregated using CLUMPAK for populations 2–6 and 9. K in Landscape biogeography and population structuring of a facultatively amphidromous galaxiid fish, Galaxias brevipinnis
Figure 3. – Average STRUCTURE results aggregated using CLUMPAK for populations 2–6 and 9. K = 6 was selected as the most likely population estimate using Evanno's method. STRUCTURE initially separated the lakes draining to the east coast (L. Wānaka and L. Wakatipu) from all other sites at K = 2. The West Coast lakes were split away next (K = 3), with L. Moeraki and L. Paringa splitting at K = 4 and L. Cristabel at K = 5. East coast L. Wānaka and L. Wakatipu were split at K = 6. L. Paringa and L. Moeraki are split form each other at K = 9.
Figure 4 in Fine-scale abundance variation in New Zealand migratory and non-migratory Galaxias fish species
Figure 4. – Representation of size-class structure of Galaxias brevipinnis in lake tributary sites with different distance categories from their recruitment sources (lakes). Sample sizes (n) and distances (in km) are shown inside the panels.
Figure 3 in Fine-scale abundance variation in New Zealand migratory and non-migratory Galaxias fish species
Figure 3. – The relationship between square-root transformed galbre Galaxias brevipinnis and non-migratory species (galpau; G. paucispondylus) abundance with distance from the lakes.
Fig. 3. A in Pathology associated with larval Eustrongylides sp. (Nematoda: Dioctophymatoidea) infection in Galaxias maculatus (Actinopterygii: Galaxiidae) from Patagonia, Argentina
Fig. 3. A. cross section of non-parasitized fish: striated hypaxial (h) and epaxial (e) musculature, Masson's trichrome. Bar = 350 μm; B. melanization (me) at one end of a cyst. Hematoxylin and Eosin. Bar = 350 μm; C. fibrotic capsule around larvae and complete disappearance of the epaxial musculature Hematoxylin and Eosin. Bar = 200 μm; D. compressive atrophy and fibrotic capsule around the parasites. cv: vertebral body, n: nematode, ns: neural spine, T. Masson. Bar = 90 μm; E. dense collagenous fibrotic capsule (arrow), parasitic cuticle (asterisk). Bar = 50 μm, F. melanin deposit (arrow). Masson's trichrome. Bar = 50 μm, G. erythrocytes (e) and melanomacrophagic centers (MMCs) around the nematode. Bar = 8 μm.
Fig. 1. A in Pathology associated with larval Eustrongylides sp. (Nematoda: Dioctophymatoidea) infection in Galaxias maculatus (Actinopterygii: Galaxiidae) from Patagonia, Argentina
Fig. 1. A. specimens of Galaxias maculatus showing melanized cysts located in the caudal peduncle. Bar = 15 mm; B. larva of Eustrongylides sp. emerging from the cyst. Bar = 1.5 mm μm; C. caudal peduncle of Galaxias maculatus showing 2 cysts, and a larva migrating through the musculature. Bar = 2.5 mm.
Fig. 2 in Pathology associated with larval Eustrongylides sp. (Nematoda: Dioctophymatoidea) infection in Galaxias maculatus (Actinopterygii: Galaxiidae) from Patagonia, Argentina
Fig. 2. Fourth-stage larva of Eustrongylides sp. from Galaxias maculatus. A. anterior end. Bar = 40 μm. Internal and external labial papillae (arrows); B. caudal extremity of male. Bar = 100 μm. Note three cuticles, outer second stage, middle third stage, and inner fourth stage (arrows).
Genome-wide analysis resolves the radiation of New Zealand’s freshwater Galaxias vulgaris complex and reveals a candidate species obscured by mitochondrial capture
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Galaxias maculatus occurrence data in marine and freshwater environments in rivers of southern Chile
<p>In the present study, we assessed ecological and historical factors (Gondwanan vicariance, marine dispersion) and potential dispersion (niche-tracking) that explain distribution of <em>Galaxias maculatus</em> in the Southern Hemisphere based on occurrences available in the Global Biodiversity Information Facility (GBIF; period 1980 to 2022) and ichthyological sampling in five river systems in southern Chile between March and November 2019. Ocurrence data extracted from GBIF are available at <a href="http://www.gbif.org">http://www.gbif.org</a> and additional ichthyological sampling data that were used are provided here. Data provided here are based on sampling of <em>Galaxias maculatus</em> at 12 sites in five river systems in southern Chile during March, May, August, and November 2019. Sampling sites were selected to cover a continuous river gradient, including (whenever possible) the lower, middle, and upper sections of each river system. Fish were captured using beach seines (5 m long, 1.5 m high, and 10 mm stretched mesh) in shoreline habitats of each evaluated river system.</p>
Vocabulario de la Guerra de las Galaxias
<p>Aquí se presentan varias de las palabras reales y ficticias del vocabulario utilizado en la saga intergaláctica de George Lucas a lo largo de sus más de 40 años de historia y que han influido a varias generaciones desde entonces hasta el dia de hoy.</p>
Galaxias maculatus occurrence data in marine and freshwater environments in rivers of southern Chile
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Morphometric Response of Galaxias maculatus (Jenyns) to Lake Colonization in Chile
<p>Body and head shape in fish responds to environmental factors such as water flow rate, food sources, and niche availability. However, the way in which fish respond to these environmental factors varies. In Central Chile, multiple river and lake systems along the coast provide an ideal study site to investigate these types of shape changes. We use geometric morphometrics to characterize shape differences in <em>Galaxias maculatus</em> (Jenyns) between river and lake populations. Lake fish converge on a shape with a more fusiform body, narrower head, and larger eyes, while river fish have a more robust body, rounder head, and smaller eyes. These shape changes are consistent with a shift to zooplanktivorous foraging in lakes, as evidenced in other systems. Unlike some fish species that develop polymorphisms in body shape after colonization (e.g., benthic and limnetic forms), <em>G. maculatus</em> in lakes exhibit a monomorphic limnetic form.</p> <p> </p>
Dataset Tylodelphys sp. effects on Galaxias maculatus
<p>Dataset of Tylodelphys sp. effects on behaviour and physiology of native fish Galaxias maculatus </p>
Data from: Balancing genetic uniqueness and genetic variation in determining conservation and translocation strategies: a comprehensive case study of threatened dwarf galaxias, Galaxiella pusilla (Mack) (Pisces: Galaxiidae)
Genetic markers are widely used to define and manage populations of threatened species based on the notion that populations with unique lineages of mtDNA and well-differentiated nuclear marker frequencies should be treated separately. However a danger of this approach is that genetic uniqueness might be emphasized at the cost of genetic diversity, which is essential for adaptation and is potentially boosted by mixing geographically separate populations. Here we re-explore the issue of defining management units, focussing on a detailed study of Galaxiella pusilla, a small freshwater fish of national conservation significance in Australia. Using a combination of microsatellite and mitochondrial markers, 51 populations across the species range were surveyed for genetic structure and diversity. We found an inverse relationship between genetic differentiation and genetic diversity, highlighting a long-term risk of deliberate isolation of G. pusilla populations based on protection of unique lineages. Instead we adopt a method for identifying genetic management units that takes into consideration both uniqueness and genetic variation. This produced a management framework to guide future translocation and re-introduction efforts for G. pusilla which contrasted to the framework based on a more traditional approach that may overlook important genetic variation in populations.
Data from: Molecular phylogeny and phylogeography of the Australian freshwater fish genus Galaxiella, with an emphasis on dwarf Galaxias (G. pusilla)
The freshwater fauna of Southern Australia is primarily restricted to the southwestern and southeastern corners of the continent, and is separated by a large, arid region that is inhospitable to this biota. This geographic phenomenon has attracted considerable interest from biogeographers looking to explain evolutionary diversification in this region. Here, we employed phylogenetic and phylogeographic approaches to evaluate the effect of this barrier on a group of four galaxiid fish species (Galaxiella) endemic to temperate Southern Australia. We also tested if continental shelf width has influenced connectivity among populations during low sea levels when rivers, now isolated, could have been connected. We addressed these questions by sampling each species across its range using multiple molecular markers (mitochondrial cytochrome b sequences, nuclear S7 intron sequences, and 49 allozyme loci). These data also allowed us to assess species boundaries, to refine phylogenetic affinities, and to estimate species ages. Interestingly, we found compelling evidence for cryptic species in G. pusilla, manifesting as allopatric eastern and western taxa. Our combined phylogeny and dating analysis point to an origin for the genus dating to the early Cenozoic, with three of the four species originating during the Oligocene-Miocene. Each Galaxiella species showed high levels of genetic divergences between all but the most proximate populations. Despite extensive drainage connections during recent low sea levels in southeastern Australia, populations of both species within G. pusilla maintained high levels of genetic structure. All populations experienced Late Pleistocene-Holocene population growth, possibly in response to the relaxation of arid conditions after the last glacial maximum. High levels of genetic divergence and the discovery of new cryptic species have important implications for the conservation of this already threatened group of freshwater species.
FIGURE 1. Cremospermopsis galaxias. A in Cremospermopsis galaxias (Gesneriaceae), a new species from northwestern Colombia
FIGURE 1. Cremospermopsis galaxias. A. Bullate leaf surface with large white spots on bullae. B. Habit. C. Front view of flower. D. Calyx. E. Inflorescence with bracts. F. Lateral view of corolla. G. Lateral view of calyx and corolla. H. Lateral view of opened flower showing androecium and staminode. I. Lateral view of opened flower showing gynoecium. J. Gynoecium showing annular nectary and stigma (from the holotype, J.L. Clark et al. 12890).
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