Haemoglobin Gene Repertoire in Teleost and Cichlid Fishes Shaped by Gene Duplications and Genome Rearrangements.

Haemoglobin is a key molecule for oxygen transport in vertebrates. It exhibits remarkable gene diversity in teleost fishes, reflecting adaptation to various aquatic environments. In this study, we present the dynamic evolution of haemoglobin subunit genes based on a comparison of high-quality genome assemblies of 24 vertebrate species, including 17 teleosts (of which six are cichlids).

Trophic ecology of the African riverine elephant fishes (Mormyridae).

Multiple species of the elephant fishes (Mormyridae) commonly coexist in sympatry in most African tropical rivers and lakes. In this study, we investigated the trophic ecology and potential trophic niche partitioning of eleven mormyrid fish species from the Sanaga River system in Cameroon using the stable isotope composition of carbon and nitrogen in the muscle samples. Albeit most mormyrids mainly feed on invertebrates, we found differences in isotope ratios, and we report signs of the trophic niche partitioning among species.

Diet and habitat as determinants of intestine length in fishes.

Unlabelled: Fish biologists have long assumed a link between intestinal length and diet, and relative gut length or Zihler's index are often used to classify species into trophic groups. This has been done for specific fish taxa or specific ecosystems, but not for a global fish dataset. Here, we assess these relationships across a dataset of 468 fish species (254 marine, 191 freshwater, and 23 that occupy both habitats) in relation to body mass and fish length.

Revision of the cichlid fish genus Gnathochromis (Teleostei: Cichlidae) from Lake Tanganyika with the description of a new genus Jabarichromis gen. nov.

The cichlid species flock from Lake Tanganyika is a well-studied system for evolutionary biology research because its species assemblage shows a high degree of endemism and is a product of adaptive radiation. While our understanding of the evolutionary history of Lake Tanganyika cichlids has advanced tremendously over the past decades, their taxonomy received considerably less attention, despite numerous taxonomic misplacements (e.g.

Species diversity and phylogeography of the group (Teleostei, Cichlidae) in eastern Brazil.

Unlabelled: Cichlid fishes are an important model system in evolutionary biology, primarily because of their exceptional diversity. However, while some cichlid assemblages, such as the ones of the African Great Lakes, have received considerable attention, others are not well studied, including many riverine species. Here, we focus on the species group and first report a new record of in the upper Paranaíba River drainage, extending the known distribution range of this genus.

Towards the phylogenetic placement of the enigmatic African genus Prolabeops Schultz, 1941.

The small cyprinid genus Prolabeops Schultz, 1941 is restricted to the Nyong and Sanaga River systems in Cameroon. In the past, the genus had been suggested to be either a member of the Labeoninae, Torinae or the Smiliogastrinae mainly on the basis of morphological similarities, and it is nowadays considered as incertae sedis within the Cypriniformes. This study provides the first attempt to reveal the phylogenetic position of Prolabeops using molecular data.

Gene expression dynamics during rapid organismal diversification in African cichlid fishes.

Changes in gene expression play a fundamental role in phenotypic evolution. Transcriptome evolutionary dynamics have so far mainly been compared among distantly related species and remain largely unexplored during rapid organismal diversification, in which gene regulatory changes have been suggested as particularly effective drivers of phenotypic divergence. Here we studied gene expression evolution in a model system of adaptive radiation, the cichlid fishes of African Lake Tanganyika.

Drivers and dynamics of a massive adaptive radiation in cichlid fishes.

Adaptive radiation is the likely source of much of the ecological and morphological diversity of life. How adaptive radiations proceed and what determines their extent remains unclear in most cases. Here we report the in-depth examination of the spectacular adaptive radiation of cichlid fishes in Lake Tanganyika.

The taxonomic diversity of the cichlid fish fauna of ancient Lake Tanganyika, East Africa.

Ancient Lake Tanganyika in East Africa houses the world's ecologically and morphologically most diverse assemblage of cichlid fishes, and the third most species-rich after lakes Malawi and Victoria. Despite long-lasting scientific interest in the cichlid species flocks of the East African Great Lakes, for example in the context of adaptive radiation and explosive diversification, their taxonomy and systematics are only partially explored; and many cichlid species still await their formal description. Here, we provide a current inventory of the cichlid fish fauna of Lake Tanganyika, providing a complete list of all valid 208 Tanganyikan cichlid species, and discuss the taxonomic status of more than 50 undescribed taxa on the basis of the available literature as well as our own observations and collections around the lake.

Where Am I? Niche constraints due to morphological specialization in two Tanganyikan cichlid fish species.

Food resource specialization within novel environments is considered a common axis of diversification in adaptive radiations. Feeding specializations are often coupled with striking morphological adaptations and exemplify the relation between morphology and diet (phenotype-environment correlations), as seen in, for example, Darwin finches, Hawaiian spiders, and the cichlid fish radiations in East African lakes. The cichlids' potential to rapidly exploit and occupy a variety of different habitats has previously been attributed to the variability and adaptability of their trophic structures including the pharyngeal jaw apparatus.

Structural manipulations of a shelter resource reveal underlying preference functions in a shell-dwelling cichlid fish.

Many animals can modify the environments in which they live, thereby changing the selection pressures they experience. A common example of such niche construction is the use, creation or modification of environmental resources for use as nests or shelters. Because these resources often have correlated structural elements, it can be difficult to disentangle the relative contribution of these elements to resource choice, and the preference functions underlying niche-construction behaviour remain hidden.

Adaptive Radiation from a Chromosomal Perspective: Evidence of Chromosome Set Stability in Cichlid Fishes (Cichlidae: Teleostei) from the Barombi Mbo Lake, Cameroon.

Cichlid fishes are the subject of scientific interest because of their rapid adaptive radiation, resulting in extensive ecological and taxonomic diversity. In this study, we examined 11 morphologically distinct cichlid species endemic to Barombi Mbo, the largest crater lake in western Cameroon, namely , , , , , , , , , , and . These species supposedly evolved via sympatric ecological speciation from a common ancestor, which colonized the lake no earlier than one million years ago.

Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon.

In deep-water animals, the visual sensory system is often challenged by the dim-light environment. Here, we focus on the molecular mechanisms involved in rapid deep-water adaptations. We examined visual system evolution in a small-scale yet phenotypically and ecologically diverse adaptive radiation, the species flock of cichlid fishes in deep crater lake Barombi Mbo in Cameroon, West Africa.

Point-Combination Transect (PCT): Incorporation of small underwater cameras to study fish communities.

Available underwater visual census (UVC) methods such as line transects or point count observations are widely used to obtain community data of underwater species assemblages, despite their known pit-falls. As interest in the community structure of aquatic life is growing, there is need for more standardized and replicable methods for acquiring underwater census data.Here, we propose a novel approach, Point-Combination Transect (PCT), which makes use of automated image recording by small digital cameras to eliminate observer and identification biases associated with available UVC methods.

Mouth dimorphism in scale-eating cichlid fish from Lake Tanganyika advances individual fitness.

Random asymmetry, that is the coexistence of left- and right-sided (or -handed) individuals within a population, is a particular case of natural variation; what triggers and maintains such dimorphisms remains unknown in most cases. Here, we report a field-based cage experiment in the scale-eating Tanganyikan cichlid Perissodus microlepis, which occurs in two morphs in nature: left-skewed and right-skewed individuals with respect to mouth orientation. Using underwater cages stocked with scale-eaters and natural prey fish, we first confirm that, under semi-natural conditions, left-skewed scale-eaters preferentially attack the right flank of their prey, whereas right-skewed individuals feed predominantly from the left side.

A complex mode of aggressive mimicry in a scale-eating cichlid fish.

Aggressive mimicry is an adaptive tactic of parasitic or predatory species that closely resemble inoffensive models in order to increase fitness via predatory gains. Although similarity of distantly related species is often intuitively implicated with mimicry, the exact mechanisms and evolutionary causes remain elusive in many cases. Here, we report a complex aggressive mimicry strategy in Plecodus straeleni, a scale-eating cichlid fish from Lake Tanganyika, which imitates two other cichlid species.

Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes.

The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region.

Adaptive divergence between lake and stream populations of an East African cichlid fish.

Divergent natural selection acting in different habitats may build up barriers to gene flow and initiate speciation. This speciation continuum can range from weak or no divergence to strong genetic differentiation between populations. Here, we focus on the early phases of adaptive divergence in the East African cichlid fish Astatotilapia burtoni, which occurs in both Lake Tanganyika (LT) and inflowing rivers.

Convergent evolution within an adaptive radiation of cichlid fishes.

The recurrent evolution of convergent forms is a widespread phenomenon in adaptive radiations (e.g., [1-9]).

The ecological and genetic basis of convergent thick-lipped phenotypes in cichlid fishes.

The evolution of convergent phenotypes is one of the most interesting outcomes of replicate adaptive radiations. Remarkable cases of convergence involve the thick-lipped phenotype found across cichlid species flocks in the East African Great Lakes. Unlike most other convergent forms in cichlids, which are restricted to East Africa, the thick-lipped phenotype also occurs elsewhere, for example in the Central American Midas Cichlid assemblage.