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328 results for “cichlid fish”
Data from: Genomics of speciation and introgression in Princess cichlid fishes from Lake Tanganyika
How variation in the genome translates into biological diversity and new species originate has endured as the mystery of mysteries in evolutionary biology. African cichlid fishes are prime model systems to address speciation-related questions for their remarkable taxonomic and phenotypic diversity, and the possible role of gene flow in this process. Here, we capitalize on genome sequencing and phylogenomic analyses to address the relative impacts of incomplete lineage sorting, introgression and hybrid speciation in the Neolamprologus savoryi-complex (the 'Princess cichlids') from Lake Tanganyika. We present a time-calibrated species tree based on whole-genome sequences and provide strong evidence for incomplete lineage sorting in the early phases of diversification and multiple introgression events affecting different stages. Importantly, we find that the Neolamprologus chromosomes show centre-to-periphery biases in nucleotide diversity, sequence divergence, GC content, incomplete lineage sorting and rates of introgression, which are likely modulated by recombination density and linked selection. The detection of heterogeneous genomic landscapes has strong implications on the genomic mechanisms involved in speciation. Collinear chromosomal regions can be protected from gene flow and harbour incompatibility genes if they reside in lowly recombining regions, and coupling can evolve between nonphysically linked genomic regions (chromosome centres in particular). Simultaneously, higher recombination towards chromosome peripheries makes these more dynamic, evolvable regions where adaptation polymorphisms have a fertile ground. Hence, differences in genome architecture could explain the levels of taxonomic and phenotypic diversity seen in taxa with collinear genomes and might have contributed to the spectacular cichlid diversity observed today.
Data from: Eco-morphological differentiation in Lake Magadi tilapia, an extremophile cichlid fish living in hot, alkaline and hypersaline lakes in East Africa
Ecological diversification through divergent selection is thought to be a major force during the process of adaptive radiations. However, the large sizes and complexity of most radiations such as those of the cichlids in the African Great Lakes make it impossible to infer the exact evolutionary history of any population divergence event. The genus Alcolapia, a small cichlid lineage endemic to Lakes Magadi and Natron in East Africa, exhibits phenotypes similar to some of those found in cichlids of the radiations of the African Great Lakes. The simplicity within Alcolapia makes it an excellent model system to investigate ecological diversification and speciation. We used an integrated approach including population genomics based on RAD-seq data, geometric morphometrics, and stable isotope analyses to investigate the eco-morphological diversification of tilapia in Lake Magadi and its satellite lake Little Magadi. Additionally, we reconstructed the demographic history of the species using coalescent simulations based on the joint site frequency spectrum. The population in Little Magadi has a characteristically upturned mouth - possibly an adaptation to feeding on prey from the water surface. Eco-morphological differences between populations within Lake Magadi are more subtle, but are consistent with known ecological differences between its lagoons such as high concentrations of nitrogen attributable to extensive guano deposits in Rest of Magadi relative to Fish Springs Lagoon. All populations diverged simultaneously only about 1,100 generations ago. Differences in levels of gene flow between populations and the effective population sizes have likely resulted in the inferred heterogeneous patterns of genome-wide differentiation.
Habitat light sets the boundaries for the rapid evolution of cichlid fish vision, while sexual selection can tune it within those limits
Cichlid fishes' famous diversity in body coloration is accompanied by a highly diverse and complex visual system. Although cichlids possess an unusually high number of seven cone opsin genes, they express only a subset of these during their ontogeny, accounting for their astonishing interspecific variation in visual sensitivities. Much of this diversity is thought to have been shaped by natural selection as cichlids inhabit a variety of habitats with distinct light environments. Also, sexual selection might have contributed to the observed visual diversity, and sexual dimorphism in coloration potentially co-evolved with sexual dimorphism in opsin expression. We investigated sex-specific opsin expression of several cichlids from Africa and the Neotropics and collected and integrated datasets on sex-specific body coloration, species-specific visual sensitivities, lens transmission and habitat light properties for some of them. We comparatively analyzed this wide range of molecular and ecological data, illustrating how integrative approaches can address specific questions on the factors and mechanisms driving diversification, and the evolution of cichlid vision in particular. We found that both sexes expressed opsins at the same levels - even in sexually dimorphic cichlid species – which argues against coevolution of sexual dichromatism and differences in sex-specific visual sensitivity. Rather, a combination of environmental light properties and body coloration shaped the diversity in spectral sensitivities among cichlids. We conclude that although cichlids are particularly colorful and diverse and often sexually dimorphic, it would appear that natural rather than sexual selection is a more powerful force driving visual diversity in this hyper-diverse lineage.
FIGURE 7 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 7. Geophagus neambi new species. Lower pharyngeal tooth-plate on occlusal view; from MCP 43671, paratype, 83.2 mm SL; scale bar 1 mm.
FIGURE 5 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 5. Rio Tocantins drainage showing the collection localities of Geophagus sveni (squares) and Geophagus neambi (circles). T represents type-localities. Some symbols represent more than one lot or locality.
FIGURE 8. Geophagus neambi new species, UNT 9631, 127.1 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 8. Geophagus neambi new species, UNT 9631, 127.1 mm SL, recently collected specimen. Lajeado, Rio Tocantins upstream Lajeado Hydroelectric Reservoir.
FIGURE 6. Geophagus neambi new species. Holotype, MCP 43670, 141.4 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 6. Geophagus neambi new species. Holotype, MCP 43670, 141.4 mm SL; Rio Tocantins, Lajeado Hydroelectric
FIGURE 3 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 3. Diagrammatic representation of lateral bar pattern of Geophagus sveni, new species, as used in this paper. Based on specimen of fig. 4.
FIGURE 4. Geophagus sveni new species, UNT 9630, 154.4 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 4. Geophagus sveni new species, UNT 9630, 154.4 mm SL, recently collected specimen. Lajeado, Rio Tocantins upstream Lajeado Hydroelectric Reservoir.
FIGURE 2 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 2. Geophagus sveni. Lower pharyngeal tooth-plate on occlusal view; from UNT 8247, paratype, 62.8 mm SL. Scale bar 1 mm.
FIGURE 1 in Two new species of cichlid fish genus Geophagus Heckel from the Rio Tocantins drainage (Perciformes: Cichlidae)
FIGURE 1. Geophagus sveni, new species. Holotype, MCP 43666, 130.3 mm SL; Rio Tocantins, Lajeado Hydroelectric Reservoir, Porto Nacional, Tocantins, Brazil.
FIGURE 5 in Crenicichla hu, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná basin in Misiones, Argentina
FIGURE 5. Crenicichla hu, lower pharyngeal tooth plate in occlusal view, AI 262, 93.9 mm SL. Scale bar: 1 mm.
FIGURE 2 in Crenicichla hu, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná basin in Misiones, Argentina
FIGURE 2. Crenicichla hu, female, holotype, MACN-ict 9429, 118.0 mm, arroyo Piray-Miní, 26°20'00"S 53°52'30"W.
FIGURE 1 in Crenicichla hu, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná basin in Misiones, Argentina
FIGURE 1. Maximum parsimony tree topology based on ND2 sequences; the dotted line displays the different topology of the alternative Bayesian inference. Numbers for each recovered node represent nonparametric bootstrap support (left) and Bayesian posterior probability (right), respectively.
FIGURE 7 in Crenicichla hu, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná basin in Misiones, Argentina
FIGURE 7. Hydrological map of the Province of Misiones. The type locality is marked with a solid circle.
FIGURE 7 in Hemitaeniochromis brachyrhynchus, a new species of cichlid fish from Lake Malaŵi, with comments on some other supposed members of the genus (Teleostei: Cichlidae)
FIGURE 7. Protomelas spilopterus, living adult individuals; MKO 80-62, MalaŴi: Lake MalaŴi: Nankumba Peninsula, ~300 m S of Otter Island, trammel nets, 9–10 Jul. 1980; M.K. Oliver, K.R. McKaye, & T.D. Kocher. a, Breeding male; b, Subordinate male or female. Note images are not to the same scale.
FIGURE 4 in Hemitaeniochromis brachyrhynchus, a new species of cichlid fish from Lake Malaŵi, with comments on some other supposed members of the genus (Teleostei: Cichlidae)
FIGURE 4. Lake MalaŴi with arrows pointing to the localities where specimens of Hemitaeniochromis brachyrhynchus were collected. Thumbi Island West: YPM 25201, holotype; Nkhata Bay: MRAC 99-41-P-1746, paratype. Scale bar = 100 km.
FIGURE 5. Hemitaeniochromis urotaenia, USNM 266842 in Hemitaeniochromis brachyrhynchus, a new species of cichlid fish from Lake Malaŵi, with comments on some other supposed members of the genus (Teleostei: Cichlidae)
FIGURE 5. Hemitaeniochromis urotaenia, USNM 266842, living; MalaŴi: Lake MalaŴi: Nankumba Peninsula between Otter Island and Chembe, off sand beach, depth 9–11 m, 3 Jul. 1980; M.K. Oliver, K.R. McKaye, & T.D. Kocher. Note the wide lacrimal bone, about equal to eye length. This specimen has an atypical midlateral stripe, usually continuous on its caudal half.
FIGURE 2 in Hemitaeniochromis brachyrhynchus, a new species of cichlid fish from Lake Malaŵi, with comments on some other supposed members of the genus (Teleostei: Cichlidae)
FIGURE 2. Hemitaeniochromis brachyrhynchus, details of YPM 25201, holotype. All scale bars = 2 mm. a, Snout region in left lateral view to show lacrimal and upper jaw. b, Lower pharyngeal bone (rostral tip at bottom of image). c, Anterior part of premaxillary dental arcade in occlusal view, after lip tissue has been pushed back and allowed to dry and shrink to reveal tooth shafts. d, Median premaxillary teeth of outer row in anterior view, after lip tissue has been pushed back and allowed to dry and shrink to reveal tooth shafts. s: Location of premaxillary symphysis. Arrow points to a tooth retaining a lateral shoulder, as seen more frequently in the smaller paratype.
FIGURE 1 in Hemitaeniochromis brachyrhynchus, a new species of cichlid fish from Lake Malaŵi, with comments on some other supposed members of the genus (Teleostei: Cichlidae)
FIGURE 1. Left and right sides of Hemitaeniochromis brachyrhynchus specimens. Not to same scale. a, YPM 25201, holotype, 123.6 mm SL, Lake MalaŴi, Thumbi Island West; b, MRAC 99-41-P-1746, paratype, 81.5 mm SL, Lake MalaŴi, Nkhata Bay.
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Allen Brain Atlas
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DANDI Archive for NWB datasets
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International Brain Laboratory public data
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OpenNeuro
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