Corbicula | |
---|---|
Corbicula leana | |
Shell of Corbicula fluminea | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Bivalvia |
Order: | Venerida |
Superfamily: | Cyrenoidea |
Family: | Cyrenidae |
Genus: | Corbicula Megerle von Mühlfeld, 1811 |
Species | |
See text. |
Corbicula is a genus of freshwater and brackish water clams, aquatic bivalve mollusks in the family Cyrenidae, the basket clams. [1] The genus name is the Neo-Latin diminutive of Latin corbis, a basket, referring to the shape and ribs of the shell.
The genus Corbicula includes numerous extant and fossil species; the status of several of them is unclear ( species inquirenda ). [2] The best known is Corbicula fluminea , an invasive species in many areas of the world.
Unusually, some members reproduce via androgenesis, wherein all genes are inherited from the male, one of the very few animals to do so. [3]
In many Asian countries, these clams are used as ingredients for soup. In South Korea, there is popular soup made of these species of clams (usually Corbicula japonica, Corbicula fluminea, Corbicula leana ) known as 재첩국 (jaechup-guk).
Androgenesis occurs rarely in the tree of life, with only a few occurrences documented and multiple mechanisms through which it is achieved. In Corbicula, androgenesis occurs through the ejection of maternal chromosomes from the egg following fertilization by sperm. [4] Fertilization in androgenetic and sexual lineages of Corbicula occurs while the developing egg is arrested at metaphase 1 of meiosis. In sexual species of Corbicula, the axis of the meiotic spindle orienting the duplicated maternal chromosomes is perpendicular to the plasma membrane of the zygote. However, androgenetic lineages of Corbicula have an axis parallel to the membrane. As a result of this unusual orientation, the two maternal polar bodies formed during anaphase 1 are extruded from the zygote, leading to the complete elimination of all maternal chromosomes. [5] [6] Androgenetic Corbicula lineages also have unreduced sperm; therefore, these lineages retain the same ploidy level after maternal chromosome extrusion. Since only maternal chromosomes are eliminated from the zygote, the zygote inherits only the paternal genome. Sperm of sexually reproducing Corbicula are uniflagellate, which is considered the ancestral trait, while androgenetic Corbicula lineages interestingly possess biflagellate sperm. [4]
While androgenesis would likely lead to species extinction in dioecious species, [7] all androgenetic lineages of Corbicula are hermaphroditic, meaning individuals can produce both sperm and egg, and these individuals can self-fertilize to create effectively clonal offspring. Androgenetic lineages of Corbicula are capable of cross-breeding with sexual and other androgenetic lineages in a phenomenon known as “egg parasitism”. [8] This leads to several interesting consequences for determining androgenetic Corbicula phylogeny. The first is a “cytonuclear mismatch” whereby the mitochondrial DNA shows congruence with the parasitized lineage but the genomic DNA is congruent with the selfish androgenetic lineage whose sperm fertilized the egg. Further complicating phylogenetic studies is the rare occurrence of partial or complete nuclear capture, when the maternal DNA is not completely eliminated from the zygote. Nuclear capture can result in genome recombination or polyploidy. Partial genome capture has been documented when native and androgenetic or multiple androgenetic lineages are sympatric. Egg parasitism has been offered as one explanation for the persistence of androgenetic lineages through increasing allele heterozygosity. [9]
Despite extensive phylogenetic study of the genus, appropriate categorization of invasive populations has remained a challenge. [10] [9] [11] Lack of clarity in their phylogeny may be due to being hermaphroditic androgens, [12] [13] though no single species of Corbicula has been described as fully androgenetic. Rather, 4-5 specific androgenetic lineages are described in the scientific literature. Form A, B, and D are found within the North America; [12] [14] Form C is in South America; [15] [12] and another form(s) has described in Europe. [9] [11] Cross-breeding between androgenetic and native Corbicula lineages have made it difficult to create a clear taxonomy of the genus, and it is still unclear whether androgenesis arose independently multiple times or originated from a smaller number of lineages that then cross-bred with sexual Corbicula species. [16] [9]
Corbicula clams are remarkably proficient invasive species, with native ranges spanning from Australia to Africa, but can now be found in most other continents. [10] In North America, Corbicula may have initially invaded as a human food source, [17] though the origin of invasion in other continents has not been determined. [18] However, genotyping may aid in tracking the number of introductions occurring in non-native habitats. [19]
Part of what contributes to its invasive success is its androgenetic reproductive strategy, wherein a single individual may be capable of creating an entire population, [10] but beyond androgenesis, Corbicula owe their invasive potential to anthropogenic factors and their life history strategies. [20] Corbicula have high reproductive capacities, [21] which may be in part due to their ability to self-fertilize, [10] and the high dispersal potential of their larvae.[ citation needed ]Corbicula are also phenotypically plastic, [22] [10] which may allow them to outcompete native mussels, [23] and their occurrence at high densities may drive native mussel glochidia mortality. [22] Their high competitive ability is of concern, in part due to the already endangered status of many of the world’s mussel species. [24] [25]
Though Corbicula are proficient competitors, they have a small number of lineages, [12] and have worldwide low genetic diversity, which is attributed to their reproductive capabilities. [26] While this generally does not contribute to their success, phenotypic plasticity may buffer them from the effects of low genetic diversity, [10] though it is suggested that population bottlenecks may have occurred during their invasions. [10] [26] [27] Despite the potential for population bottlenecks, there is a need for better control methods, [11] as active spread has occurred. [28] [29] While some eradication methods work, such as deposition of dry ice pellets, [30] the use of a heat torch, [31] and temperature shock, [32] preventative measures are of utmost importance as invasives are often difficult to detect prior to establishment. [11]
Extant species within the genus Corbicula include: [2]
Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shells of equal size connected by two adductor muscles and have a powerful burrowing foot. They live in both freshwater and marine environments; in salt water they prefer to burrow down into the mud and the turbidity of the water required varies with species and location; the greatest diversity of these is in North America.
In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils.
The Dreissenidae are a family of small freshwater mussels, aquatic bivalve molluscs. They attach themselves to stones or to any other hard surface using a byssus. The shells of these bivalves are shaped somewhat like those of true mussels, and they also attach themselves to a hard substrate using a byssus; however, this group is not at all closely related to true mussels, being more closely related to the venus clams (Veneridae).
The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids.
Corbicula fluminea is a species of freshwater clam native to eastern Asia which has become a successful invasive species throughout the world, including North America, South America, Europe, and New Zealand. It is native to freshwater environments of Eastern Asia, including Russia, Thailand, the Philippines, China, Taiwan, Korea, and Japan. C. fluminea also occurs naturally in freshwater environments of Africa. Corbicula fluminea is commonly known in the west as the Asian clam, Asiatic clam, or Asian gold clam. In Southeast Asia, C. fluminea is known as the golden clam, prosperity clam, pygmy clam, or good luck clam. In New Zealand, it is commonly referred as the freshwater gold clam.
The Corbiculidae are a family of clams in the mollusc order Venerida. They are known commonly as basket clams. The family name comes from the root corbus ("basket"), and was inspired by the concentric ribbing of the shells.
Sphaerium is a genus of very small freshwater clams, aquatic bivalve molluscs in the family Sphaeriidae, known as the fingernail clams. The small clams in this genus are unusual in that many of them, such as Sphaerium corneum, can climb around underwater on aquatic plants, using their long and strong foot.
Unionida is a monophyletic order of freshwater mussels, aquatic bivalve molluscs. The order includes most of the larger freshwater mussels, including the freshwater pearl mussels. The most common families are the Unionidae and the Margaritiferidae. All have in common a larval stage that is temporarily parasitic on fish, nacreous shells, high in organic matter, that may crack upon drying out, and siphons too short to permit the animal to live deeply buried in sediment.
Lampsilis higginsii is a rare species of freshwater mussel known as Higgins' eye pearly mussel or simply Higgins' eye. It is endemic to the United States, where it occurs in the upper Mississippi River and the drainages of some of its tributaries. It is threatened by the introduced zebra mussel. Lampsilis higginsii is a federally listed endangered species.
Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves.
Corbicula japonica is an edible species of brackishwater clam, a bivalve mollusk in the family Cyrenidae, the basket clams. Its common names include Japanese basket clam, Japanese blue clam, and shijimi.
Potomida littoralis is a species of bivalve belonging to the family Unionidae.