Three-spined stickleback
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Three-spined stickleback ( Gasterosteus aculeatus ) |
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| Gasterosteus aculeatus | ||||||||||||
| Linnaeus , 1758 |
The three-spined stickleback ( Gasterosteus aculeatus , Latin aculeatus - prickly) is a well-known fish .
Economically, the three-spined stickleback is largely insignificant, but due to its high degree of distribution and its robustness it is known in broad sections of the population and was already described in the Systema Naturae by Carl von Linné . The popularity of this fish is also reflected in the large number of local names: snot perch, large stickleback, spiny perch, stechbüttel, wolf, plugling, stitch bag, etc.
Its complex reproductive behavior made it a popular object of investigation in behavioral research. In Germany it was named Fish of the Year 2018.
distribution and habitat
The three-spined stickleback occurs, with the exception of the Danube Delta, all over Europe, Algeria, North Asia and North America. It inhabits standing and flowing water and lives in fresh water as well as in coastal salt and brackish water . Typically, he lives in plant-rich areas with sandy or muddy ground.
The populations living in the coastal area migrate into fresh water during spawning time .
The IUCN lists the three-spined stickleback as "not endangered".
features
The three-spined stickleback reaches a total length of up to eleven centimeters, whereby the maximum size is more likely to be reached by the specimens living in salt water. The body is relatively high back compared to the representatives of other stickleback genera. The relative height of the body depends on the inhabited habitat; Saltwater populations and residents of large inland lakes tend to be slimmer than sticklebacks from flowing waters.
Female and juvenile animals as well as males who are not ready to reproduce usually have a simple black-brown marbling on a light, silvery background. The back is colored darker than the belly. The silver sheen is particularly pronounced in saltwater populations. Basically the color varies depending on the habitat, brass yellow and completely black populations are also known. During the spawning season , adult males wear a brightly colored breeding dress: the marbling recedes and the underside turns an intense orange-red color from the tip of the snout to the stalk of the tail. The back and the iris of the eyes take on a light turquoise.
Like all sticklebacks , the three-spined stickleback does not have scales . However, it forms bone plates that overlap like roof tiles, which distinguish three hereditary variants:
- forma trachurus (completely labeled)
- The sides of the body are completely covered with 29 to 35 shields from the gill cover to the tail stalk.
- forma semiarmatus (incompletely shielded )
- The lateral shields consist only of a row of bone plates and a caudal keel on the front half and the shields on the caudal peduncle, with a bare area in between.
- forma leiurus (little shielded )
- There are no more than four to ten bone plates without a caudal keel in the anterior part of the trunk.
During its development, the form trachurus goes through phases with initially little and then incomplete signage ( pedomorphosis ) before it has formed a complete row of lateral plates with a standard length of 2.2 to 2.5 centimeters. In the case of the other two variants, this development process is terminated in earlier development phases. The form leiurus occurs exclusively in freshwater, while the other two represent marine migratory forms.
The three (rarely four) erect spines in front of the dorsal fin give it its name and are particularly striking. Between the head and the soft-radiated dorsal fin sit six bone plates, the third, fourth and sixth of which each carry one of the spines. The pelvic fins also each have a long, powerful spine. With these disgusting spines, the fish can protect itself to a certain extent from attack by larger fish, since the splayed spines injure the enemy's lips when biting.
The pectoral fins are large, as they are primarily used to generate propulsion. Swim with side blows with the tail fin is only of secondary importance and is only relevant when you are fleeing quickly or swimming against strong currents.
Number of fin rays :
- Dorsal 1 III (IV) (these are the dorsal spines)
- Dorsal 2 10-14
- Anal I / 8-11
- Caudal 12
- Pectoral 10
- Ventral I / 1
behavior
The extremely agile swimmers feed on numerous small animals (insect larvae, worms) but also on fish spawn and fry. The ingestion of food is often very greedy. For example, it is possible to briefly lift a three-spined stickleback out of the water on a worm that it is trying to devour.
The defensive armament , which is more effective than other species of sticklebacks, allows the Gasterosteus species to no longer build their nests in the protection of more or less dense vegetation, but to use the soil of relatively poorly covered areas. At the beginning of the spawning season, the male first makes several digging attempts in the selected breeding area and then concentrates on a place where it digs a shallow hollow. Already in this phase it starts to create nesting material, algae of the genus Spirogyra are often used. If these are not available or not available in sufficient quantities, other fine-thread construction materials are also used. By repeatedly spitting it out, letting it drift and picking it up again, the properties of the building material are checked during transport to the building site. However, it is still unclear which criteria are used. If the nest is a second or third building, the old nests are often used as material dispensers. When the opportunity arises, the nests of neighboring male sticklebacks are "robbed". The material is first piled up in the excavated pit and stuck together with a kidney secretion. The stickleback strokes the nesting substrate with its curved body and trembling caudal and pelvic fins. The construction is increasingly solidified and anchored in the ground by repeated bumps with the mouth alternating with renewed gluing. Once the building has reached a sufficient size, first a lateral recess is formed with horizontal jaws and then the actual nesting cavity. From this point on, new building material is preferably draped and glued around the entrance. In the meantime, the nest is fanned vigorously with the pectoral fins, probably to test the strength. Towards the end of the construction phase, the owner spits on his nest with sand. In particular, the edges of the immediate surroundings are aligned. If the male stickleback swims into the brood cavity and squeezes through the less solidified back wall, the nest is ready. The construction of the nesting site can take a few hours, but also several days. The construction time depends primarily on the testosterone level of the male, but also secondarily on favorable framework conditions such as the availability of suitable building material and above all the presence of females willing to mate.
As soon as the nest is ready, a female ready to spawn is attracted with arcs ("zigzag dance"). This presents her bulging belly (because of the eggs), whereupon the male shows her the nest entrance lying sideways. The female then penetrates the nest and spawns, while the male pokes at her tail and back with its mouth ("Schnauzentriller"). Immediately afterwards the female leaves the nest on the side opposite the entrance, while the eggs are inseminated by the male. After the spawning act has been completed, the male drives his partner out of the breeding ground. This process can be repeated with other females, who in turn can spawn up to six times in one spawning period.
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The male alone is responsible for protecting and caring for the brood. After spawning, it stands in front of the nest entrance and uses its pectoral fins to constantly fan fresh water over the clutch. Eggs that have fallen out are collected again by the male and brought back into the clutch. The young sticklebacks hatch after seven to twelve days and then stay in the nest for a few more days. When they first try to swim, they are caught again by their father and brought back to the nest. During the entire spawning and brood care period, the male behaves in an extremely territorial manner. Especially after the young have hatched, not only members of the sexes are attacked, but also female sticklebacks and alien animals (if their size allows it).
The spawning season is extremely stressful for both sexes and many sticklebacks die after their first spawning period. Outside of the breeding season, they live in loose flocks.
The three-spined stickleback is not particularly long-lived and only reaches an age of two to three years.
evolution
After the retreat of the glaciers of the last Pleistocene , the originally marine three-spined stickleback conquered the freshwater. By conquering new habitats, which can be subdivided into river and lake habitats , they had to adapt to new conditions such as predators, food supply, hiding places and other habitat changes through natural selection . Because of these different selection conditions, different phenotypes developed and a remarkable polymorphism arose .
This can be seen, for example, in the form of the lateral signage in different habitats . The lateral signage is mainly used to protect against predators and is already fully developed in the marine ancestors. With the settlement of the rivers, however, the selection conditions changed. Since there are many more hiding places in rivers than in the open sea, the importance of protective shields has lost its importance. In this way, phenotypes with less well-trained signage were also able to establish themselves . As a result, there are more incompletely and poorly educated individuals in river populations than in the populations of their marine ancestors.
As they reached the rivers, the three-spined sticklebacks also spread in the adjacent lakes, in which, like their marine ancestors, they had to survive in open water. So it was again an advantage to have well-trained signage, as the individuals living there are much more exposed to their predators due to fewer hiding places. So the individuals with full signage were again preferentially selected and this led to more fully signposted individuals in lake populations. The simultaneous selection of a feature in different directions is called parallel evolution . The expression of different genetic variations and their constant mixing through migration led to a polymorphism .
Various researches try to explain the signage in the three-spined stickleback genetically and to identify the responsible genes . A responsible gene, which codes for the labeling , is ectodysplasin ( EDA ), it is located on chromosome 4. Although EDA is responsible for a large part of the phenotypic expression, it does not explain 100% of the characteristic expression. This does not indicate a classically Mendelian trait , but rather a more complex interaction of several genes with regard to a trait.
Due to the parallel evolution , the formation of polymorphisms and the abundance in the whole world, the three-spined stickleback has become an important model organism in evolutionary biology .
Special
Due to its diverse manifestations, the three-spined stickleback has been described many times anew, for example the variants trachurus , semiarmatus and leiurus were previously considered separate species. As a result, there are at least 33 synonyms for this species.
swell
literature
- Fritz Roth: About the construction and development of the skin armor of Gasterosteus aculeatus (= anatomical indicator ), Jena 1919, DNB 571113877 (dissertation University of Jena 1919, 24 pages).
- Hans-Joachim Paepke: The sticklebacks. Gasterosteidae. Westarp Sciences, Magdeburg 1996, ISBN 3-89432-492-9 .
- Günter Sterba: Freshwater fish in the world. Weltbild, Augsburg 1998, ISBN 3-89350-991-7 .
- Kurt Deckert: Fish, amphibians, reptiles (= Urania animal kingdom. Volume 4). Urania, Leipzig 1991, ISBN 3-332-00376-3
- Richard Muckle: The three-spined stickleback (Gasterosteus aculeatus L.) in Lake Constance , in: Writings of the Association for the History of Lake Constance and its Surroundings , 90th year 1972, pp. 249-258 ( digitized version )
Individual evidence
- ↑ Three-spined stickleback on Fishbase.org (English)
- ↑ http://www.bund-hessen.de/themen_und_projekte/natur_und_artenschutz/natur_erleben/s/stichling/
- ↑ Speciation in nature: the threespine stickleback model systems. In: www.sciencedirect.com. Retrieved April 4, 2016 .
- ↑ John A. Baker, Matthew A. Wund, Rachel Y. Chock, Lauren Ackein, Ragan Elsemore: Predation history and vulnerability: Conservation of the stickleback adaptive radiation . In: Biological Conservation . tape 143 , no. 5 , May 1, 2010, p. 1184–1192 , doi : 10.1016 / j.biocon.2010.02.026 ( sciencedirect.com [accessed April 4, 2016]).
- ^ Daniel Berner, Anne-Catherine Grandchamp, Andrew P. Hendry: Variable Progress Toward Ecological Speciation in Parapatry: Stickleback Across Eight Lake-Stream Transitions . In: evolution . tape 63 , no. 7 , July 1, 2009, ISSN 1558-5646 , p. 1740–1753 , doi : 10.1111 / j.1558-5646.2009.00665.x ( wiley.com [accessed April 4, 2016]).
- ↑ Pamela F. Colosimo, Kim E. Hosemann, Sarita Balabhadra, Guadalupe Villarreal, Mark Dickson: Widespread Parallel Evolution in Sticklebacks by Repeated Fixation of Ectodysplasin Alleles . In: Science . tape 307 , no. 5717 , March 25, 2005, ISSN 0036-8075 , p. 1928–1933 , doi : 10.1126 / science.1107239 , PMID 15790847 ( sciencemag.org [accessed April 5, 2016]).
- ↑ Marius Roesti, Benjamin Kueng, Dario Moser, Daniel Berner: The genomics of ecological vicariance in threespine stickleback fish . In: Nature Communications . tape 6 , November 10, 2015, p. 8767 , doi : 10.1038 / ncomms9767 , PMID 26556609 , PMC 4659939 (free full text) - ( nature.com [accessed April 5, 2016]).
Web links
- Three-spined stickleback on Fishbase.org (English)
- Gasterosteus aculeatus in the endangered Red List species the IUCN 2009 Posted by: J. Freyhof, M. Kottelat, 2008. Accessed October 19 of 2009.
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