Most empirical studies support a decline in speciation rates through time, although evidence for constant speciation rates also exists. Declining rates have been explained by invoking pre-existing niches, whereas constant rates have been attributed to non-adaptive processes such as sexual selection and mutation. Trends in speciation rate and the processes underlying it remain unclear, represent...

Constraints on form should determine how organisms diversify. Owing to competition for the limited space within the body, investment in adjacent structures may frequently represent an evolutionary compromise. For example, evolutionary trade-offs between eye size and jaw muscles in cichlid fish of the African great lakes are thought to represent a constructional constraint that influenced the di...

Reduced male aggression towards different phenotypes generating negative frequency-dependent intrasexual selection has been suggested as a mechanism to facilitate the invasion and maintenance of novel phenotypes in a population. To date, the best empirical evidence for the phenomenon has been provided by laboratory studies on cichlid fish with different colour polymorphisms. Here we experimenta...

The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evolution of the sex-determination system in these fish, we performed cytogenetic analysis in 11 cichlid...

Abstract Female cichlid fish living in African great lakes are known to have sensory systems that adapted ambient light environments. These system adaptations hypothesized influenced the evolution of diverse male nuptial coloration. In rock-dwelling Lake Malawi mbuna cichlids, however, extent which environments influence female and potentially associated coloration remains unknown. Yet, ubiquit...

Geographic isolation is suggested to be among the most important processes in the generation of cichlid fish diversity in East Africa's Great Lakes, both through isolation by distance and fluctuating connectivity caused by changing lake levels. However, even broad scale phylogeographic patterns are currently unknown in many non-cichlid littoral taxa from these systems. To begin to address this,...

a number of studies have attempted to demonstrate the antibacterial properties of skin mucus from different species of fish such as turbot, atlantic salmon, rainbow trout, gold fish, seabass, seabream, flounder, barramundi, cichlid and yellowtail . however, most have suffered from alack of definitive data concerning the virulence of the organisms used for in vitro assessment of antibacterial pr...

Adaptive phenotypic plasticity, the ability of an organism to change its phenotype to match local environments, is increasingly recognized for its contribution to evolution. However, few empirical studies have explored the molecular basis of plastic traits. The East African cichlid fish Astatoreochromis alluaudi displays adaptive phenotypic plasticity in its pharyngeal jaw apparatus, a structur...

Direction of mouth-opening of a small herbivorous Tanganyikan cichlid, Telmatochromis temporalis, was studied. Each sample fish opened its mouth either rightward or leftward in some degree. The directions of mouth-opening were independent of the body curve directions, and the asymmetry will be due to asymmetric mouth morph individually specific. The degree of the mouth asymmetry was not related...

In this study we explore the possible role of phenotypic plasticity in the process of adaptation and evolutionary change in the African cichlid Pseudocrenilabrus multicolor victoriae. Parental fish were collected from a hypoxic swamp, a lake ecotone, and a river in Uganda. Broods (F1) were split and grown under hypoxia or normoxia. We measured morphological parameters of the gill apparatus, str...