Pelvicachromis taeniatus

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Pelvicachromis taeniatus
Pelvicachromis taeniatus, color form "Nigerian Red"

Pelvicachromis taeniatus , color form "Nigerian Red"

Systematics
Order : Cichliformes
Family : Cichlids (Cichlidae)
Subfamily : Pseudocrenilabrinae
Tribe : Chromidotilapiini
Genre : Pelvicachromis
Type : Pelvicachromis taeniatus
Scientific name
Pelvicachromis taeniatus
( Boulenger , 1901)

Pelvicachromis taeniatus is a small cichlid from West Africa. The species is kept in Germany as an ornamental fish, but is rarely offered in the trade. The trivial terms emerald splendor perch or strip splendor perch are occasionally used. Most of the animals offered are wild-caught.

distribution and habitat

P. taeniatus inhabits standing and flowing waters from Benin to the Niger Delta and occurs there from the mouths of the rivers up to about 50 km inland. For the former the type attributed populations from Cameroon the species was Pelvicachromis kribensis revalidated, for the population of the Cameroon River Wouri the species was in 2014 Pelvicachromis drachenfelsi erected. The habitat is characterized by low water hardness and a mostly low pH value . The water temperatures are 22 to 25 degrees Celsius. P. taeniatus can often be found near the bank, where it uses the protection of overhanging vegetation. Although it is basically a freshwater fish, it also visits the brackish water zones of the rivers.

features

As is typical of the genus Pelvicachromis , the females of P. taeniatus with a length of six centimeters lag slightly behind the males, which reach a length of eight centimeters. The unpaired fins of the males are strongly drawn out, those of the females are rounded. Vertical rows of red and blue spots cover the caudal fin of the males. Colored spots can also be found in the soft rayed part of the male dorsal and anal fin. The females have mostly colorless anal fin, dorsal and caudal fin are mostly yellowish in color.

P. taeniatus forms a wide variety of color variations.

Fins formula : dorsal XVII – XVIII / 7–8, anal III / 7

Reproduction

Pelvicachromis taeniatus is a socially monogamous cave breeder. The males compete with each other for areas with breeding caves. The females, in turn, compete for access to the territorial males. After spawning, the female takes care of the eggs in the cave, while the male mainly guards the cave outside. After six to eight days, the larvae leave the cave and are led through the female, while the male attacks potential predators from a greater distance. The joint brood care extends over four to six weeks.

In Pelvicachromis taeniatus , due to the high costs of brood care, both sexes are picky when choosing a partner, which is why the species has established itself in research as a model organism for mutual partner selection. Noticeable is z. B. the ornamentation of both sexes: males show, among other things, a yellow belly color, while females develop a purple belly. Females prefer yellow to pale males when choosing a partner. Males themselves prefer females with a large extension of the purple abdominal surface. The ornament of the females serves as an indicator of the individual quality and is therefore one of the few examples of functional female coloring in biology: the purple area predicts the number of eggs and the willingness of a female to spawn, from which picky males benefit. Females with extensive ornamentation are also more active in caring for the brood and more successful in fights with less ornamented competitors. Furthermore, both genders prefer the greatest possible partner. The resulting sexual conflict is resolved by the choice of partners on both sides in a mating among similarly sized fish ( assortative mating ). Males also prefer females with large pelvic fins, which has led to an increase in the size of the female pelvic fin over the course of evolution. The allometry of the female's ventral fin increases the most in relation to body size than other fins. Using the example of Pelvicachromis taeniatus , an influence of male partner choice on the relationships of the female body could be demonstrated for the first time.

Pelvicachromis taeniatus shows a peculiarity rarely observed in animals in pair formation: fish of the Moliwepopulation are actively inbreeding. If they have the choice to mate with siblings or unrelated fish, the choice usually falls on a sibling as a partner. In a sibling pairing, the males invest more time in guarding the clutch than the males in a pair of unrelated fish. The advantage of such inbreeding is that both partners share genetic material with each other and so each individual can pass on more genes to the offspring than would be the case with unrelated fish. Although this behavior usually leads to negative consequences for the offspring, there is no evidence of inbreeding depression in Pelvicachromis taeniatus . Experiments in captivity showed that the parents' brood care efforts were dependent on the nutritional status of the offspring. In general, as the brood grows, the effort required to care for the parent animals decreases. This is more pronounced, the weaker the offspring, better nourished and therefore larger offspring are cared for longer. The authors of the study explain the earlier neglect of weaker offspring with the lower costs for the parent animals, which can thus invest more energy in future offspring.

Individual evidence

  1. ^ Rüdiger Riel, Hans A. Baensch : Aquarienatlas . Mergus Verlag, Melle 2002, ISBN 3-88244-065-1 . (1st volume) p. 752
  2. ↑ Lamboj, A., Bartel, D. & dell'Ampio, E. (2014): Revision of the Pelvicachromis taeniatus-group (Perciformes), with revalidation of the taxon Pelvicachromis kribensis (Boulenger, 1911) and description of a new species . Cybium, 38 (3): 205-222
  3. ↑ a b Timo Thünken, Theo CM Bakker, Sebastian A. Baldauf, Harald Kullmann: Active inbreeding in a cichlid fish and its adaptive significance . In Current Biology . Volume 17, Issue 3, February 6, 2007, ISSN  0960-9822 , doi : 10.1016 / j.cub.2006.11.053 . Pp. 225–229 ( PDF; 103.5 KiB ( Memento of the original from September 8, 2014 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice . ) @1@ 2Template: Webachiv / IABot / download.cell.com
  4. ↑ Sebastian A. Baldauf, Harald Kullmann, Timo Thünken, Stephanie Winter, Theo CM Bakker (2009): Computer animation as a tool to study preferences in the cichlid fish Pelvicachromis taeniatus . In Journal of Fish Biology . Volume 75, pp. 738-746.
  5. ↑ Sebastian A. Baldauf, Harald Kullmann, Theo CM Bakker, Timo Thünken (2011): Female nuptial coloration and its adaptive significance in a mutual mate choice system . In Behavioral Ecology. Volume 22, pp. 478-485.
  6. ↑ Sebastian A. Baldauf, Harald Kullmann, Stefanie H. Schroth, Timo Thünken, Theo CM Bakker: You can't always get what you want: size assortative mating by mutual mate choice as a resolution of sexual conflict . In BMC Evolutionary Biology, Volume 9: 129, doi : 10.1186 / 1471-2148-9-129 , ( [1] )
  7. ↑ Sebastian A. Baldauf, Theo CM Bakker, Fabian Herder, Harald Kullmann, Timo Thünken: Male mate choice scales female ornament allometry in a cichlid fish . In BMC Evolutionary Biology, Volume 10: 301, doi : 10.1186 / 1471-2148-10-301 , ( [2] ).
  8. ↑ Timo Thünken, Denis Meuthen, Theo CM Bakker, Harald Kullmann: Parental investment in relation to offspring quality in the biparental cichlid fish Pelvicachromis taeniatus . In Animal Behavior . Volume 80, 2010, ISSN  0003-3472 . Pp. 69-74.

literature

Web links

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