Neolamprologus pulcher is a species of cichlid endemic to Lake Tanganyika. The common names for N. pulcher include daffodil cichlid, fairy cichlid, princess of Zambia and lyretail cichlid. This species can reach a length of TL. It can also be found in the aquarium trade.
Taxonomy and phylogeny
Previously, it was believed that N. pulcher and N. brichardi were two distinct species. Now they are considered the same species, the only difference being that Neolamprologus brichardi has a black stripe running from its eye to its gill cover and a yellow spot just above it, both of which are absent in N. pulcher. Because Neolamprologus pulcher is the older of the two scientific names, the rules of scientific nomenclature would make this the correct name for the species. The daffodil cichlid, when it was still known as N. brichardi, was named after Pierre Brichard, a Belgian who set up a collection station, for the export of Tanganyikan cichlids in 1971, named "Fishes of Burundi."
Distribution and habitat
Daffodil cichlids are endemic to Lake Tanganyika, Africa and are widespread in the southern part of the lake. They are found along the rocky coastlines of the countries of Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. There are a number of different geographical varieties. The variety known as the "daffodil" is very popular and is found along the steep rocky slopes of Kantalamba and Kambwinba.
Like other Lamprologini cichlids, daffodil cichlids are highly variable and are found in all kinds of habitats. They are found both at the surface and in very deep waters, but all species are substrate spawners. They have a body that can be somewhat elongated to very elongated. Their colors tend to be brown, yellow, blue, black or a combination of all four. Black is usually a striping, either vertical or horizontal. Like other genera in the tribe, N. pulcher will readily mate with females of other Lamprologini.
Daffodil cichlids inhabit rocky coastlines and swim in large schools that often consist of hundreds of fish. When breeding, however, they will form monogamous pairs and spawn in caves. They are found in waters at depths of 32 feet (10 m) or deeper. They feed on swarms of plankton drifting in the lake water along with microorganisms such as small crustaceans and invertebrates.
Description
Daffodil cichlids are graceful fish with bodies that are elongated with a continuous dorsal fin. The tail fin is lyre-shaped and they develop long flowing filaments on all unpaired fins. They usually reach up to about in length, but can sometimes get a bit bigger in the aquarium reaching up to . They can live 8 – 10 years with proper care.
These fish have a light-colored tan body washed with hints of yellow and bluish-purple spots. The yellow is stronger along the upper portion of the body and onto the dorsal fin, and around the base of the pectoral fin. There are two vertical crescent-shaped bars just behind the eye highlighted with a bit of blue. The dorsal fin is lyre-shaped and they develop long flowing filaments on all unpaired fins. The fins are tipped with an icy blue. They have brilliant blue eyes.
Behavior
Feeding
Daffodil cichlids are omnivorous and feed on swarms of plankton in the water column as well as small crustaceans and invertebrates.
Cooperative breeding
The daffodil cichlid inhabits permanent social groups composed of one breeding pair and helpers of both sexes. Absolute breeding success (assessed by a combined measure of clutch size and egg survival probability) has been shown to be higher for breeding pairs with helpers compared to those without helpers. Egg size tends to decrease as the number of helpers within groups increases, which suggests that the presence of helpers enables breeder females to strategically reduce their investment per egg in a manner that maximizes breeder fitness.
When parents and helpers care for offspring, the protection may reduce the predation risk to offspring, which may allow mothers to invest less per single offspring. Daffodil cichlid helpers protect the group offspring and reduce the offspring's mortality rate. Therefore, dominant females are expected to reduce their investment per egg when more helpers are present. Experiments show that females do indeed reduce egg size with increasing number of helpers but not when perceived neighbor density is high.
Kin recognition
In cooperatively breeding groups that have a mix of related and unrelated individuals, being able to identify and differentially cooperate with relatives can bring indirect fitness (biology) benefits to helpers. When given a choice between associating with unfamiliar kin or unfamiliar non-kin, juvenile daffodil cichlids spend a significantly longer time associating with kin. Relatedness, rather than familiarity, is more important in the association preferences of the daffodil cichlid, which is advantageous because not all familiar individuals within a cooperatively breeding group are relatives. Having the ability to recognize kin from non-kin brings fitness advantages through kin selection and inbreeding avoidance.
Kin selection can explain the evolution of cooperative breeding, and the distribution of relatives within a population may influence the benefits of cooperative behavior. Females are more likely to inherit the breeding position of their mother or sister in larger groups. Helper to breeder relatedness decreases steeply with increasing helper age, particularly for breeding males. Helper to helper relatedness is age-associative and also declines with age.
Social status
Since daffodil cichlids are a species that uses cooperative breeding, this means that each individual is ranked in terms of social status. Breeders have a higher social rank than non-breeders. Social status has significant effects on daffodil cichlid behavior.
Physiological differences
Within a group of breeding and helper cichlids, there exists a dominance hierarchy among every fish in the group. The breeder males and females are dominant individuals who have offspring, while the helper cichlids are subordinate. Dominance is typically determined by size. The effect of social position was investigated on growth rates and other physical conditions. In the absence of breeders, dominant individuals had higher liver glycogen levels and grew the most. Dominant fish in groups of breeders and helpers had significantly higher plasma cortisol concentrations when paired with subordinates. These results suggest that dominant individuals experience higher cortisol levels as well as higher growth rates since higher cortisol levels in the blood indicate that an individual either has less stress or better internal control when stressed. These increased levels of cortisol possibly correlate with size determining rank within the dominance hierarchy.
Competition for mates
Mature males may compete for fertilization opportunities with females due to the existence of a dominance hierarchy in competitive breeders. Studies have suggested that socially subordinate helper males sneak fertilizations from dominant breeding males. If sneaking does happen, then sperm competition will select for increased reproductive investment by subordinate sneaking males, relative to those of dominant males. This reproductive investment exists in daffodil cichlids in the form of reproductive suppression. Breeders have considerably larger testes than helpers, as well as faster- and longer-swimming sperm and a higher percentage of motile sperm compared to helpers. The sperm of large helpers are characteristically similar to those of breeders, but helpers have smaller testes. The small size of the helpers' testes, coupled with the physiological equivalence of their sperm compared to breeder sperm, imply that the helpers are reproductively suppressed.
Multiple paternity
Mixed parentage is not too uncommon in the daffodil cichlid. Genetic data collected in groups of daffodil cichlids from Lake Tanganyika revealed mixed parentage in 80% of the examined groups. A case of shared maternity was detected when a subordinate female bred alongside the dominant female in a social group. This was not found to be true for the males, though. Extra-pair paternity was assigned to other dominant males who held their own social groups, but no subordinate males were found to have fathered any young in any of the examined groups.
The degree of multiple paternity in a population of daffodil cichlids is important because sneaking fertilization often results in multiple paternity. The dominant male usually sires all offspring, but not always. When twelve different broods were looked at, it was found that 44.2% of the young were not fathered by the dominant male, and multiple paternity was found in 5 of 12 broods (41.7%), with 8 of 35 young (22.9%) being sired by males other than the territory owning breeder males. This is an exceptionally high rate of extra-pair paternity among cooperative breeding vertebrates, which suggests that male helpers may have produced these young before being expelled from the territory in response to their reproductive parasitism.
Liver investment
Social status and sex also influence how much daffodil cichlids invest in their livers. Males and females (controlling for body size) have similar liver investment, and subordinates of both sexes have relatively larger livers compared with dominants. Social status results in liver size disparity because it is hypothesized that liver mass reflects status-dependent differences in energy expenditure, but not energy storage or energy acquisition. Dominants perform more energetically costly behaviors (e.g. social policing and care) compared with subordinates, supporting the notion that energy expenditure drives liver investment. Dominants in large groups with many subordinates to monitor and dominants that own multiple territories with a large area to patrol tend to have smaller livers. Subordinates do not appear to use the liver as a strategic energy storage organ. Although subordinates feed more frequently than dominants, a negative correlation is found between feeding rates and liver size. This provides evidence that liver investment patterns are linked to status-driven differences in energy expenditure but not energy intake or storage.
Flexibility in dominance hierarchy
The social hierarchy is not rigid, as helpers can also become breeders. The most common way for the change is via dispersion into other groups. When helpers disperse by moving into other groups, they can increase their status by becoming a breeder or by moving up in the dominance hierarchy.
In addition to dispersing to join a new group, subordinates may also gain dominant breeding status by inheriting the top position of their current group. Inheritance happens whenever the dominant individual dies or leaves the group. The pathway to breeder status varies between males and females as a result of sex differences in the costs of dispersal and inbreeding. In one study, 71% of male vacancies were filled by joiners. Joiners are incoming fish that are not originally part of the group. However, only 15% of female vacancies were filled. Helpers increase their frequency of cooperative behavior following the removal of a female breeder but not after the removal of a male breeder. This suggests that female breeder vacancies are typically filled by subordinate helpers who inherit from within the group, and male breeder vacancies are commonly filled by joining individuals, who are either existing breeders or helpers from other groups.
Physiological consequences of behavior