Sexually divergent selection, allometric constraints, and the evolution of sexual dimorphism in cichlids from Lake Tanganyika.

The evolution of sexual dimorphism is widely acknowledged as a manifestation of sex-specific genetic architecture. Although empirical studies suggested that sexual dimorphism evolves as a joint consequence of constraints arising from genetic architecture and sexually divergent selection, it remains unclear whether and how these established microevolutionary processes scale up to the macroevolutionary patterns of sexual dimorphism among taxa. Here, we studied how sexual selection and parental care drive sexual dimorphism in cichlid fishes from Lake Tanganyika.

A new linkage group involved in sex determination in haplotilapiine cichlids.

The high diversity of sex chromosomes and sex determination systems among haplotilapiines suggests that this large cichlid clade is a good model for investigating the evolution of genetics of sex determination. Nonetheless, information about sex determination in this clade remains sparse. The present study reports a microsatellite marker that is closely associated with sex in Xenotilapia rotundiventralis from Lake Tanganyika, Africa.

Mapping of quantitative trait loci underlying a magic trait in ongoing ecological speciation.

Background: Telmatochromis temporalis is a cichlid fish endemic to Lake Tanganyika. The normal and dwarf morphs of this fish are a clear example of ongoing ecological speciation, and body size plays an important role in this speciation event as a magic trait. However, the genetic basis underlying this trait has not been studied.

Brood parasitism of an open-water spawning cichlid by the cuckoo catfish.

The cuckoo catfish Synodontis multipunctatus and S. grandiops are endemic to Lake Tanganyika and the only known nonavian vertebrates that exhibit obligate interspecific brood parasitism. Seven maternal mouth-brooding cichlid fish species are reported to be natural hosts of the parasitic catfish and share a common reproductive behaviour that the catfish exploits: cichlid females spawn eggs on the bottom, allowing the catfish female to place her eggs near the cichlid eggs, and the cichlid females collect the catfish eggs by mouth together with their own eggs.

A robust phylogeny among major lineages of the East African cichlids.

The huge monophyletic group of the East African cichlid radiations (EAR) consists of thousands of species belonging to 12-14 tribes; the number of tribes differs among studies. Many studies have inferred phylogenies of EAR tribes using various genetic markers. However, these phylogenies partly contradict one another and can have weak statistic support.

A RAD-based phylogenetics for Orestias fishes from Lake Titicaca.

The fish genus Orestias is endemic to the Andes highlands, and Lake Titicaca is the centre of the species diversity of the genus. Previous phylogenetic studies based on a single locus of mitochondrial and nuclear DNA strongly support the monophyly of a group composed of many of species endemic to the Lake Titicaca basin (the Lake Titicaca radiation), but the relationships among the species in the radiation remain unclear. Recently, restriction site-associated DNA (RAD) sequencing, which can produce a vast number of short sequences from various loci of nuclear DNA, has emerged as a useful way to resolve complex phylogenetic problems.

Application of RAD-based phylogenetics to complex relationships among variously related taxa in a species flock.

Restriction site-associated DNA (RAD) sequences from entire genomes can be used to resolve complex phylogenetic problems. However, the processed data matrix varies depending on the strategies used to determine orthologous loci and to filter loci according to the number of taxa with sequence data for the loci, and often contains plenty of missing data. To explore the utility of RAD sequences for elucidating the phylogenetics of variously related species, we conducted RAD sequencing for the Ohomopterus ground beetles and attempted maximum-likelihood phylogenetic analyses using 42 data matrices ranging from 1.

Competition-driven speciation in cichlid fish.

Theoretically, competition can initiate divergence in habitat use between individuals of a species, leading to restricted gene flow and eventual speciation. Evidence that sister species differ in habitat use is commonplace and consistent with this mechanism, but empirical experimental support is surprisingly scarce. Here we provide evidence that competition has taken a key role in the evolution of genetically distinct ecomorphs of the Lake Tanganyika cichlid fish Telmatochromis temporalis.

Genetic and Morphological Evidence Implies Existence of Two Sympatric Species in Cyathopharynx furcifer (Teleostei: Cichlidae) from Lake Tanganyika.

Although the cichlid fishes from Lake Tanganyika are treated as a textbook example of adaptive radiation, many taxonomic problems remain unresolved. Cyathopharynx furcifer, which belongs to the currently monospecific genus Cyathopharynx, contains two colour morphs at the southern end of the lake: one has a yellow anal fin, and the other has a black anal fin. Some books for hobbyists of ornamental fish treat these morphs as different species, but taxonomic studies have neither mentioned the existence nor addressed the status of these colour morphs.

Invisible pair bonds detected by molecular analyses.

A focus on pair bonds between males and females is fundamental to study the evolution of social organization. Because pair bonds are generally identified from direct observations of pairs that maintain physical proximity, pair bonds may have been overlooked in animals that do not exhibit such visible pairs. The Lake Tanganyika cichlid fish Xenotilapia rotundiventralis forms schools that consist of mouthbrooding and non-brooding adults in mid-water, and visible pairs are not recognized.

The adaptive radiation of cichlid fish in lake tanganyika: a morphological perspective.

Lake Tanganyika is the oldest of the Great Ancient Lakes in the East Africa. This lake harbours about 250 species of cichlid fish, which are highly diverse in terms of morphology, behaviour, and ecology. Lake Tanganyika's cichlid diversity has evolved through explosive speciation and is treated as a textbook example of adaptive radiation, the rapid differentiation of a single ancestor into an array of species that differ in traits used to exploit their environments and resources.

Sperm motility adaptation to ion-differing aquatic environments in the Tanganyikan cichlid, Astatotilapia burtoni.

The cichlid fish, Astatotilapia burtoni, can acclimate and reproduce in both the K(+)-, Na(+)-, and Ca(2+)-rich waters of Lake Tanganyika (pH 8.9-9.2) and the surrounding rivers where K(+), Na(+), and Ca(2+) concentrations are low (pH 6.

Evidence of disassortative mating in a Tanganyikan cichlid fish and its role in the maintenance of intrapopulation dimorphism.

Morphological dimorphism in the mouth-opening direction ('lefty' versus 'righty') has been documented in several fish species. It has been suggested that this deflection is heritable in a Mendelian one-locus, two-allele fashion. Several population models have demonstrated that lateral dimorphism is maintained by negative frequency-dependent selection, resulting from interactions between predator and prey species.