[Show abstract][Hide abstract] ABSTRACT: The discovery of fluorescent proteins has revolutionized experimental biology. Whereas the majority of fluorescent proteins have been identified from cnidarians, recently several fluorescent proteins have been isolated across the animal tree of life. Here we show that biofluorescence is not only phylogenetically widespread, but is also phenotypically variable across both cartilaginous and bony fishes, highlighting its evolutionary history and the possibility for discovery of numerous novel fluorescent proteins. Fish biofluorescence is especially common and morphologically variable in cryptically patterned coral-reef lineages. We identified 16 orders, 50 families, 105 genera, and more than 180 species of biofluorescent fishes. We have also reconstructed our current understanding of the phylogenetic distribution of biofluorescence for ray-finned fishes. The presence of yellow long-pass intraocular filters in many biofluorescent fish lineages and the substantive color vision capabilities of coral-reef fishes suggest that they are capable of detecting fluoresced light. We present species-specific emission patterns among closely related species, indicating that biofluorescence potentially functions in intraspecific communication and evidence that fluorescence can be used for camouflage. This research provides insight into the distribution, evolution, and phenotypic variability of biofluorescence in marine lineages and examines the role this variation may play.
[Show abstract][Hide abstract] ABSTRACT: Objective:
Troglomorphic fishes provide excellent comparative models for studying eye evolution. We describe the gross and microscopic anatomy of ocular structures of the depigmented, blind cichlid, Lamprologus lethops, and its putative sister species, Lamprologus tigripictilis collected from the lower Congo River in the Democratic Republic of Congo.
Both species were fixed, paraffin-sectioned and stained. Immunohistochemical staining for rhodopsin markers was also performed.
The globe in L. lethops is smaller than its sighted congener and recessed beneath bone and skin. The scleral profile maintains a wrinkled spherical shape, and the choroid is occupied by adipose tissue containing no rete mirabilis. The globe in L. lethops is foreshortened in the anterior-posterior dimension and deviated dorsally toward the midline with no extraocular muscles. At the posterior pole of the globe, there is an open periocular space containing no cell bodies. In L. tigripictilis, no choroidal adipose tissue is seen and a rete mirabilis is present. The retina of L. lethops is thinner compared with L. tigripictilis. Both species have scleral cartilage and fully developed lenses. Rhodopsin is present in the inner and outer segments of both species.
Ocular adaptations evolve over time as a response to a life in darkness. Combining ocular anatomy, developmental data, and genetics will lead to insights about evolution in these fishes and contribute to understanding how ocular evolution works in other vertebrates.
Full-text · Article · Nov 2012 · Veterinary Ophthalmology
[Show abstract][Hide abstract] ABSTRACT: Lake Tanganyika comprises a cichlid species flock with substrate-breeding and mouthbrooding lineages. While sexual selection via mate choice on male mating color is thought to boost speciation rates in mouthbrooding cichlids, this is not the case in substrate-breeding lamprologines, which mostly form stable pairs and lack sexual dichromatism. We present a comprehensive reconstruction of the evolution of the cichlid tribe Lamprologini, based upon mtDNA sequences and multilocus nuclear DNA (AFLP) markers. Twelve mtDNA clades were identified, seven of which were corroborated by the AFLP tree. The radiation is likely to have started about 5.3 MYA, contemporarily with that of the mouthbrooding C-lineage, and probably triggered by the onset of deep-water conditions in Lake Tanganyika. Neither the Congo- nor the Malagarazi River species form the most ancestral branch. Several conflicts in the mtDNA phylogeny with taxonomic assignments based upon color, eco-morphology and behavior could be resolved and complemented by the AFLP analysis. Introgressive hybridization upon secondary contact seems to be the most likely cause for paraphyly of taxa due to mtDNA capture in species involving brood-care helpers, while accidental hybridization best explains the para- or polyphyly of several gastropod shell breeders. Taxonomic error or paraphyly due to the survival of ancestral lineages appear responsible for inconsistencies in the genera Lamprologus and Neolamprologus.
Full-text · Article · Oct 2010 · Molecular Phylogenetics and Evolution
[Show abstract][Hide abstract] ABSTRACT: It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood.
We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, Teleogramma depressum and Lamprologus tigripictilis, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In L. tigripictilis, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for T. depressum despite significant differentiation at mtDNA and nDNA microsatellite markers.
The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.
Full-text · Article · May 2010 · BMC Evolutionary Biology
[Show abstract][Hide abstract] ABSTRACT: The Congo River Lamprologus are revised and two new species are described. Lamprologus teugelsi, n.sp., from Malebo Pool and the lower Congo River rapids, and L. tigripictilis, n.sp., from the lower Congo River rapids, are readily distinguished from the remaining Congo River Lamprologus based on counts, measurements, osteology, and color pattern. Monophyly of the Congo River Lamprologus species is tentatively accepted and a key to the group is provided. All available collection localities for re-identified Lamprologus material from the Congo River are plotted for each species. Maps of collection localities reveal large distributional voids, suggesting that Congo River lamprologine diversity remains incompletely sampled.
Preview · Article · Sep 2009 · American Museum Novitates
[Show abstract][Hide abstract] ABSTRACT: A new species of Alestes from the Mpozo River in the Bas Congo Province of the Democratic Republic of Congo Is described and diagnostic characters for the genus are presented. Alestes inferus, new species, is differentiated from all other members of the genus by its lower and non-overlapping lateral-line scale count (31-33 versus 36-51) and its reduced and non-overlapping vertebral count (39-40 versus 41-49). Within Alestes, the new species appears to be most closely related to A. macrophthalmus and A. liebrechtsii, based on the shared possession by these three species of a tubular, bony extension enclosing the olfactory nerve on the lateral ethmoid, and bifurcated lateral-line canals terminating in two pores. Alestes liebrechtsii and A. inferus are the only species of the genus known from the lower Congo River.
[Show abstract][Hide abstract] ABSTRACT: Lepidiolamprologus mimicus n. sp. is described from material collected along the Zambian coast of Lake Tanganyika. It is distinguished from congeners by its unique color pattern of bright yellow fins, a brownish-tan flank coloration and large, dark brown spots along the flanks, in addition to a series of meristic and morphometric characters. Lepidiolampro-logus mimicus n. sp. exhibits an interesting feeding ecology, in which individuals blend into schools of their prey, yel-low-finned cyprichromines, with the aid of similar coloration. This is the first instance of aggressive mimicry reported for lamprologines.
[Show abstract][Hide abstract] ABSTRACT: Nanochromis teugelsi, new species, is described from the Kasai Region and the main channel of the Congo as far upstream as Lake Tumba. It differs from N. dimidiatus, N. sabinae, and N. squamiceps in lacking a supraneural bone and in lacking scales on the nape, cheek and chest. It has a more elevated upper lateral line, contiguous to the dorsal-fin base from about the 6 th pored scale on. In addition to distinguishing coloration characters, N. teugelsi is distinguished from N. minor, N. transvestitus, N. nudiceps, N. wickleri and N. splendens by its fully scaled opercle, from N. consortus by its shorter and shallower caudal peduncle, and from N. parilus by a lower number of gill rakers on the first arch.
Full-text · Article · Oct 2006 · Ichthyological Exploration of Freshwaters
[Show abstract][Hide abstract] ABSTRACT: In the course of ongoing survey work in the lower Congo River, two collections of an undescribed species of the predatory cyprinid genus Raiamas have been made; one in the Congo main channel in the vicinity of Inga, and a second in the Inkisi River, a large south bank tributary of the Congo. Discovery of this new taxon has prompted a reexamination of potentially related taxa of adjacent regions and an attempt to provide generic diagnoses for the morphologically similar cyprinid genera Leptocypris, Raiamas, and Opsaridium. Based on a series of derived features of the neurocranium, pectoral girdle, jaws, and suspensorium, anatomical diagnoses for the three cyprinid genera are provided. We reassign Opsaridium christyi to Raiamas and Raiamas weeksii to Leptocypris. These two generic reassignments and the discovery of the new Raiamas bring the number of species of Raiamas confirmed from the lower Congo River to four: R. salmolucius, R. buchholzi, R. christyi, and the new species, R. kheeli, described herein. The reassignment of Opsaridium weeksii to Leptocypris raises the number of species of Leptocypris recorded from the region to four: L. modestus, L. lujae, L. weynsii, and L. weeksii.
[Show abstract][Hide abstract] ABSTRACT: A new labeonine cyprinid, Labeo fulakariensis, is described from material recently collected in rapids on the lower Congo River near the mouth of the Foulakari River, a large north bank tributary, in the Republic of Congo, and from the Yelala rapids in the Democratic Republic of Congo. The new species is readily distinguished from other Congolese Labeo except L. greenii and L. reidi by the following combination of characters: plicate lips, characteristic striping of the flanks, and a dark spot on the base of the caudal peduncle. Labeo fulakariensis is distinguished from L. greenii by dorsal fin shape and snout without a deep transverse furrow or upwardly directed fleshy anterior appendage, and from L. reidi by the position of the eyes, the circumpeduncular scale count (16 vs 17 to 20 in L. reidi) and maxillary barbels hidden and smaller than in L. reidi.
[Show abstract][Hide abstract] ABSTRACT: Using sequences of the mitochondrial NADH dehydrogenase subunit 2 gene (ND2, 1047bp) and a segment of the non-coding mitochondrial control region, as well as nuclear sequences including two introns from the S7 ribosomal protein and the loci TmoM25, TmoM27, and UME002, we explore the phylogenetic relationships of Lepidiolamprologus, one of seven lamprologine cichlid genera in Lake Tanganyika, East Africa. Analyses consisted of direct optimization using POY, including a parsimony sensitivity analysis, and maximum likelihood and Bayesian inference for comparison. With respect to Lepidiolamprologus, the results based on the mitochondrial dataset were robust to parameter variation in POY. Lepidiolamprologus cunningtoni was resolved in a large clade sister to ossified group lamprologines, among which the remaining Lepidiolamprologus were nested. In addition to L. attenuatus, L. elongatus, L. kendalli, and L. profundicola, Neolamprologus meeli, N. hecqui, N. boulengeri, N. variostigma, and two undescribed species were resolved in a two-pore Lepidiolamprologus clade sister to Lamprologus callipterus and two species of Altolamprologus. Lepidiolamprologus nkambae, in marked conflict with morphological and nuclear DNA evidence, nested outside of the two-pore Lepidiolamprologus clade, suggesting that the mtDNA signal has been convoluted by introgressive hybridization.
Full-text · Article · Mar 2006 · Molecular Phylogenetics and Evolution