Heteroxeny, or heteroxenous development, characterizes a parasite whose development involves several host species. [1] Heteroxeny has been used as the basis for splitting genera. [2]
When there are two or three hosts, the development cycle is named diheteroxenous or triheteroxenous, respectively. More ambiguously, these terms are sometimes synonymized as dixenous or trixenous. [1]
The etymology of the terms heteroxeny / heteroxenous derives from the two ancient Greek words ἕτερος (héteros), meaning "other, another, different", and ξένος (xénos), meaning "foreign". [3] [4]
In mycology, the term heteroecious has also been used for parasitic fungi with multiple hosts, and the terms can be used synonymously. [5]
The Apicomplexa are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of plastid called an apicoplast, and an apical complex structure. The organelle is an adaptation that the apicomplexan applies in penetration of a host cell.
In cladistics for a group of organisms, monophyly is the condition of being monophyletic—that is, a group of taxa that share a common ancestry. The resulting group is called a monophyletic group or clade, composed only of a common ancestor and its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics (synapomorphies), which distinguish organisms in the clade from other organisms. A related term is holophyly, the condition of being holophyletic—that is, a common ancestor and all descended taxa.
Parasitism is a symbiotic relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism, trophically transmitted parasitism, vector-transmitted parasitism, parasitoidism, and micropredation.
A heteroecious parasite is one that requires at least two hosts. The primary host is the host in which the parasite spends its adult life; the other is the secondary host. Both the primary host and an unrelated alternate host are required for the parasite to complete its life cycle. This can be contrasted with an autoecious parasite which can complete its life cycle on a single host species. Many rust fungi have heteroecious life cycles:
The heterotrichs are a class of ciliates. They typically have a prominent adoral zone of membranelles circling the mouth, used in locomotion and feeding, and shorter cilia on the rest of the body. Many species are highly contractile, and are typically compressed or conical in form. These include some of the largest protozoa, such as Stentor and Spirostomum, as well as many brightly pigmented forms, such as certain Blepharisma.
A polyphyletic group is a set of organisms, or other evolving elements, that have been grouped together but do not share an immediate common ancestor. The term is often applied to groups that share characteristics that appear to be similar but have not been inherited from common ancestors; these characteristics are known as homoplasies, and the development and phenomenon of homoplasies is known as convergent evolution. The arrangement of the members of a polyphyletic group is called a polyphyly.
A dendrogram is a diagram representing a tree. This diagrammatic representation is frequently used in different contexts:
Crithidia is a genus of trypanosomatid Euglenozoa. They are parasites that exclusively parasitise arthropods, mainly insects. They pass from host to host as cysts in infective faeces and typically, the parasites develop in the digestive tracts of insects and interact with the intestinal epithelium using their flagellum. They display very low host-specificity and a single parasite can infect a large range of invertebrate hosts. At different points in its life-cycle, it passes through amastigote, promastigote, and epimastigote phases; the last is particularly characteristic, and similar stages in other trypanosomes are often called crithidial.
The painted tree-rat is a species of spiny rat from Brazil, restricted to north-eastern Bahia in eastern Brazil. It is the only species in the genus Callistomys.
The tuft-tailed spiny tree rat is a spiny rat species from South America. It is known from Brazil south of the Amazon River, where it has been found in grassland and gallery forest. It is the only species in the genus Lonchothrix. Very little is known about this rodent. It is small with an average adult weight of about 138 grams. It is nocturnal and solitary in habits.
The long-tailed armored tree-rat, Makalata macrura, is a spiny rat species from South America. It is found in Brazil, with a population in Ecuador which is referable either to this species or to Makalata didelphoides. Initially considered a large form of the latter species, it actually represents a distinct species as supported by morphological and molecular characters.
Mesomys is a genus of South American spiny rats in the family Echimyidae.
Anoura is a genus of leaf-nosed bats from Central and South America. Anoura members lack or have a short tail, and are nectarivorous bats of small to medium size among the Phyllostomidae.
Monoxenous development, or monoxeny, characterizes a parasite whose development is restricted to a single host species.
Bellardia trixago is a species of flowering plant in the family Orobanchaceae. Only member of the monotypic genus Bellardia, it is known as trixago bartsia or Mediterranean lineseed. This plant is native to the Mediterranean Basin, but it is known in other places with similar climates, such as California and parts of Chile, where it is an introduced species and noxious weed.
Protozoa is an informal term for a group of single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris. Historically, protozoans were regarded as "one-celled animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae. Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to describe single-celled protists that feed by heterotrophy. Some examples of protozoa are Amoeba, Paramecium, Euglena and Trypanosoma.
Loxodes is a genus of karyorelictean ciliates, belonging to family Loxodidae. It is the only known karyorelictean ciliate that lives in freshwater habitats.
Rhynchocorys is a small genus of flowering plants belonging to the family Orobanchaceae, formerly classified in the family Scrophulariaceae. It is native to Europe, Morocco and Algeria.
Blastocrithidia is a genus of parasitic flagellate protist belonging to the family Trypanosomatidae. It is a monoxenous parasite of heteropteran insects, mainly inhabiting their hindgut and glands.
Leptomonas is a genus of parasitic flagellate protist belonging to family Trypanosomatidae and subfamily Leishmaniinae sensu Maslov & Lukeš 2012. It is a monoxenous parasite of mainly Hemiptera, Diptera, and Siphonaptera insects.
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