Three-spined stickleback
Encyclopedia
The three-spined stickleback, Gasterosteus aculeatus, is a fish
native to much of northern Europe
, northern Asia
and North America
. It has been introduced into parts of southern and central Europe.
are currently recognised by the IUCN:
These subspecies actually represent three examples from the enormous range of morphological variation present within three-spined sticklebacks. These fall into two rough categories, the anadromous
and the freshwater
forms.
The anadramous form spends most of its adult life eating plankton and fish in the sea, and returns to freshwater to breed. The adult fish are typically between 6 and 10 cm long, and have 30 to 40 lateral armour plates along their sides. They also have long dorsal
and pelvic
spines. The anadromous form is morphologically similar all around the Northern Hemisphere
, such that anadromous fish from the Baltic, the Atlantic and the Pacific all resemble each other quite closely.
Three-spined stickleback populations are also found in freshwater lakes and streams. These populations were probably formed when anadromous fish started spending their entire life cycle in freshwater, and thus evolved
to live there all year round. Freshwater populations are extremely morphologically diverse, to the extent that many observers (and some taxonomists) would describe a new subspecies of three-spined stickleback in almost every lake
in the Northern Hemisphere. One consistent difference between freshwater populations and their anadromous ancestors is the amount of body armour, as the majority of freshwater fish only have between 0 and 12 lateral armour plates, and shorter dorsal and pelvic spines. However, there are also large morphological differences between lakes. One major axis of variation
is between populations found in deep, steep sided lakes and those in small, shallow lakes. The fish in the deep lakes typically feed in the surface waters on plankton, and often have large eyes, with short, slim bodies and an upturned jaw. Some researchers refer to this as the limnetic
form. Fish from shallow lakes feed mainly on the lake bed, and are often long and heavy bodied with a relatively horizontal jaw and a small eye. These populations are referred to as the benthic
form.
Since each watershed
was probably colonised separately by anadromous sticklebacks, it is widely believed that morphologically similar populations in different watersheds or on different continents evolved independently. There is a unique population in the meromictic
Pink Lake
in Gatineau Park
, Quebec
.
One fascinating aspect of this morphological variation is that a number of lakes contain both a limnetic and a benthic type, and these do not interbreed with each other. Evolutionary biologists often define species
as populations that do not interbreed with each other (the Biological Species Concept), and thus the benthics and limnetics within each lake would constitute separate species. These species pairs are an excellent example of how adaptation to different environments (in this case feeding in the surface waters or on the lake bed) can generate new species. This process has come to be termed ecological speciation. This type of species pairs is found in British Columbia
in Western Canada. The lakes themselves only contain three-spined sticklebacks and cutthroat trout
, and all are on islands. Tragically, the pair in Hadley Lake on Lasqueti Island
was destroyed in the mid 1980s by the introduction of a predatory catfish, and the pair in Enos Lake on Vancouver Island
has started to interbreed and are no longer two distinct species. The two remaining pairs are on Texada Island
, in Paxton Lake and Priest Lake
, and they are listed as Endangered in the Canadian Species At Risk Act.
Other species pairs which consist of a well-armored marine form and a smaller, unarmored fresh water form are being studied in ponds and lakes in Southcentral Alaska that were once marine habitats such as those uplifted during the 1964 Alaska earthquake. The evolutionary dynamics of these species pairs are providing a model for the processes of speciation which has taken place in less than 20 years in at least one lake. In 1982, a chemical eradication program intended to make room for trout and salmon at Loberg Lake, Alaska killed the resident freshwater populations of sticklebacks. Oceanic sticklebacks introduced through nearby Cook Inlet recolonized the lake. In just 12 years beginning in 1990, the frequency of the oceanic form dropped steadily, from 100% to 11%, while a variety with fewer plates increased to 75% of the population, with various intermediate forms making up another small fraction. This rapid evolution is thought to be possible through genetic variations that confer competitive advantages for survival in freshwater when conditions shift rapidly from salt to freshwater. However, the actual molecular basis of this evolution still remains unknown.
Although sticklebacks are found in many locations around the coasts of the Northern Hemisphere and are thus viewed by the IUCN as species of least concern
, the unique evolutionary history encapsulated in many freshwater populations indicates that further legal protection may be warranted. The IUCN indicates that this evaluation may be out of date.
Many populations take 2 years to mature and experience only one breeding season before dying and some can take up to 3 years to reach maturity. However, some freshwater populations and populations at extreme latitudes can reach maturity in only 1 year. In spring, males defend territories
where they build nests on the bottom of the pond or other body of water; the sequence of territorial, courtship and mating behaviours was described in detail by Niko Tinbergen in a landmark early study in ethology
. Territorial males develop a red chin and belly colouration, and Tinbergen showed that the red colour acted as a simple sign stimulus, releasing aggression in other males and the first steps in the courtship sequence from gravid females. Red colouration is produced from carotenoids found in the diet of the fish. As carotenoids cannot be synthesised de novo, the degree of colouration gives an indication of male quality, with higher quality males showing more intense colouration. However, it is noteworthy that the response to red is not universal across the entire species complex, with black throated populations often found in peat-stained waters. Males also develop blue irises on maturation. Only the males care for the eggs once they are fertilised. Parental care is intense, involving nest maintenance and fanning of the eggs to ensure a fresh water supply, even at night. Males build the nests from vegetation, sand, pebbles and other debris, adhering the material together with spiggin, a proteinaceous glue-like substance secreted from the kidneys. Sticklebacks have four colour photoreceptor cells in their retina
, making them potentially tetrachromatic. They are capable of perceiving ultraviolet
wavelengths of light invisible to the human eye and use such wavelengths in their normal behavioural repertoire.
The three-spined stickleback is a known intermediate host for the hermaphroditic parasite Schistocephalus solidus
, a tapeworm of fish and fish-eating birds.
was recently sequenced by the Broad Institute
and many other genetic resources are available. This population is under risk from the presence of introduced northern pike
in a nearby lake.
by Charles Dickens
. Samuel Pickwick is said to have published a treatise on the subject of tittlebats, specifically the ones living in the ponds of Hampstead
.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
native to much of northern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, northern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It has been introduced into parts of southern and central Europe.
Distribution and morphological variation
Three subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
are currently recognised by the IUCN:
- Gasterosteus aculeatus aculeatus is found in most of the species range, and is the subspecies most strictly termed the three-spined stickleback; its common name in BritainUnited KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
is the tiddler, although "tittlebat" is also sometimes used. - G. a. williamsoni, the unarmored threespine stickleback, is found only in North America; its recognised range is southern CaliforniaCaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, though there are isolated reports of it occurring in British ColumbiaBritish ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
and MexicoMexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
; - G. a. santaeannae, the Santa Ana stickleback, is also restricted to North America.
These subspecies actually represent three examples from the enormous range of morphological variation present within three-spined sticklebacks. These fall into two rough categories, the anadromous
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
and the freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
forms.
The anadramous form spends most of its adult life eating plankton and fish in the sea, and returns to freshwater to breed. The adult fish are typically between 6 and 10 cm long, and have 30 to 40 lateral armour plates along their sides. They also have long dorsal
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
and pelvic
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
spines. The anadromous form is morphologically similar all around the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
, such that anadromous fish from the Baltic, the Atlantic and the Pacific all resemble each other quite closely.
Three-spined stickleback populations are also found in freshwater lakes and streams. These populations were probably formed when anadromous fish started spending their entire life cycle in freshwater, and thus evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
to live there all year round. Freshwater populations are extremely morphologically diverse, to the extent that many observers (and some taxonomists) would describe a new subspecies of three-spined stickleback in almost every lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
in the Northern Hemisphere. One consistent difference between freshwater populations and their anadromous ancestors is the amount of body armour, as the majority of freshwater fish only have between 0 and 12 lateral armour plates, and shorter dorsal and pelvic spines. However, there are also large morphological differences between lakes. One major axis of variation
Variation
- Physics :* Magnetic variation, difference between magnetic north and true north, measured as an angle* Variation , any perturbation of the mean motion or orbit of a planet or satellite, particularly of the moon- Mathematics :* Bounded variation...
is between populations found in deep, steep sided lakes and those in small, shallow lakes. The fish in the deep lakes typically feed in the surface waters on plankton, and often have large eyes, with short, slim bodies and an upturned jaw. Some researchers refer to this as the limnetic
Limnetic zone
The limnetic zone is the well-lit, open surface waters in a lake, away from the shore. The vegetation of the littoral zone surrounds this expanse of open water and it is above the profundal zone....
form. Fish from shallow lakes feed mainly on the lake bed, and are often long and heavy bodied with a relatively horizontal jaw and a small eye. These populations are referred to as the benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
form.
Since each watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
was probably colonised separately by anadromous sticklebacks, it is widely believed that morphologically similar populations in different watersheds or on different continents evolved independently. There is a unique population in the meromictic
Meromictic
A meromictic lake has layers of water that do not intermix. In ordinary, "holomictic" lakes, at least once each year there is a physical mixing of the surface and the deep waters...
Pink Lake
Pink Lake
Pink Lake is a meromictic lake located in Gatineau Park, Quebec, Canada. The surface of the waters are a deep green due to the abundance of algae in the water. The lake is in danger of eutrophication due to human activities...
in Gatineau Park
Gatineau Park
Gatineau Park is a park located in the National Capital Region, in Quebec's Outaouais region, just north of Ottawa, Ontario. Administered by the National Capital Commission, the park is a 361 km² wedge of land to the west of the Gatineau River...
, Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
.
One fascinating aspect of this morphological variation is that a number of lakes contain both a limnetic and a benthic type, and these do not interbreed with each other. Evolutionary biologists often define species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
as populations that do not interbreed with each other (the Biological Species Concept), and thus the benthics and limnetics within each lake would constitute separate species. These species pairs are an excellent example of how adaptation to different environments (in this case feeding in the surface waters or on the lake bed) can generate new species. This process has come to be termed ecological speciation. This type of species pairs is found in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
in Western Canada. The lakes themselves only contain three-spined sticklebacks and cutthroat trout
Cutthroat trout
The cutthroat trout is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the many fish species colloquially known as trout...
, and all are on islands. Tragically, the pair in Hadley Lake on Lasqueti Island
Lasqueti Island
Lasqueti Island is an island off the east coast of Vancouver Island in the Strait of Georgia, Powell River Regional District, British Columbia, Canada. A passenger-only ferry connects the island to the community of French Creek, near Parksville...
was destroyed in the mid 1980s by the introduction of a predatory catfish, and the pair in Enos Lake on Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
has started to interbreed and are no longer two distinct species. The two remaining pairs are on Texada Island
Texada Island
Texada Island is the largest island in the Strait of Georgia of British Columbia, Canada. Its northern tip is located about southwest of the city of Powell River and west of the Sechelt Peninsula on the Sunshine Coast. A former mining and logging area, the island still has a few quarries and old...
, in Paxton Lake and Priest Lake
Priest Lake
Priest Lake, Idaho, United States is located in the northernmost portion of the Idaho Panhandle, 80 miles north of Spokane Washington, with the northern end of the lake extending to within 15 miles of the Canadian border. The primary lake, lower Priest is 19 miles long and over 300 feet deep...
, and they are listed as Endangered in the Canadian Species At Risk Act.
Other species pairs which consist of a well-armored marine form and a smaller, unarmored fresh water form are being studied in ponds and lakes in Southcentral Alaska that were once marine habitats such as those uplifted during the 1964 Alaska earthquake. The evolutionary dynamics of these species pairs are providing a model for the processes of speciation which has taken place in less than 20 years in at least one lake. In 1982, a chemical eradication program intended to make room for trout and salmon at Loberg Lake, Alaska killed the resident freshwater populations of sticklebacks. Oceanic sticklebacks introduced through nearby Cook Inlet recolonized the lake. In just 12 years beginning in 1990, the frequency of the oceanic form dropped steadily, from 100% to 11%, while a variety with fewer plates increased to 75% of the population, with various intermediate forms making up another small fraction. This rapid evolution is thought to be possible through genetic variations that confer competitive advantages for survival in freshwater when conditions shift rapidly from salt to freshwater. However, the actual molecular basis of this evolution still remains unknown.
Although sticklebacks are found in many locations around the coasts of the Northern Hemisphere and are thus viewed by the IUCN as species of least concern
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
, the unique evolutionary history encapsulated in many freshwater populations indicates that further legal protection may be warranted. The IUCN indicates that this evaluation may be out of date.
Life history
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
where they build nests on the bottom of the pond or other body of water; the sequence of territorial, courtship and mating behaviours was described in detail by Niko Tinbergen in a landmark early study in ethology
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
. Territorial males develop a red chin and belly colouration, and Tinbergen showed that the red colour acted as a simple sign stimulus, releasing aggression in other males and the first steps in the courtship sequence from gravid females. Red colouration is produced from carotenoids found in the diet of the fish. As carotenoids cannot be synthesised de novo, the degree of colouration gives an indication of male quality, with higher quality males showing more intense colouration. However, it is noteworthy that the response to red is not universal across the entire species complex, with black throated populations often found in peat-stained waters. Males also develop blue irises on maturation. Only the males care for the eggs once they are fertilised. Parental care is intense, involving nest maintenance and fanning of the eggs to ensure a fresh water supply, even at night. Males build the nests from vegetation, sand, pebbles and other debris, adhering the material together with spiggin, a proteinaceous glue-like substance secreted from the kidneys. Sticklebacks have four colour photoreceptor cells in their retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
, making them potentially tetrachromatic. They are capable of perceiving ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
wavelengths of light invisible to the human eye and use such wavelengths in their normal behavioural repertoire.
The three-spined stickleback is a known intermediate host for the hermaphroditic parasite Schistocephalus solidus
Schistocephalus solidus
Schistocephalus solidus is a tapeworm of fish, fish-eating birds and rodents.This hermaphroditic parasite belongs to the Eucestoda subclass, of class Cestoda. It parasitizes fish and fish-eating water birds. The fish-eating water bird is the definitive host and reproduction occurs in the bird's...
, a tapeworm of fish and fish-eating birds.
Genetics
Three-spined sticklebacks have recently become a major research organism for evolutionary biologists trying to understand the genetic changes involved in adapting to new environments. The entire genome of a female fish from Bear Paw Lake in AlaskaAlaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
was recently sequenced by the Broad Institute
Broad Institute
The Broad Institute is a genomic medicine research center located in Cambridge, Massachusetts, United States. Although it is independently governed and supported as a 501 nonprofit research organization, the institute is formally affiliated with the Massachusetts Institute of Technology, Harvard...
and many other genetic resources are available. This population is under risk from the presence of introduced northern pike
Northern Pike
The northern pike , is a species of carnivorous fish of the genus Esox...
in a nearby lake.
In popular culture
The three-spined stickledback is also known as a tittlebat, and was featured in The Pickwick PapersThe Pickwick Papers
The Posthumous Papers of the Pickwick Club is the first novel by Charles Dickens. After the publication, the widow of the illustrator Robert Seymour claimed that the idea for the novel was originally her husband's; however, in his preface to the 1867 edition, Dickens strenuously denied any...
by Charles Dickens
Charles Dickens
Charles John Huffam Dickens was an English novelist, generally considered the greatest of the Victorian period. Dickens enjoyed a wider popularity and fame than had any previous author during his lifetime, and he remains popular, having been responsible for some of English literature's most iconic...
. Samuel Pickwick is said to have published a treatise on the subject of tittlebats, specifically the ones living in the ponds of Hampstead
Hampstead
Hampstead is an area of London, England, north-west of Charing Cross. Part of the London Borough of Camden in Inner London, it is known for its intellectual, liberal, artistic, musical and literary associations and for Hampstead Heath, a large, hilly expanse of parkland...
.