''Alloteropsis'' (from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''allotrios'' ("strange") and ''opsis'' ("appearance")) is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Old World The "Old World" () is a term for Afro-Eurasia coined by Europeans after 1493, when they became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia in the Eastern Hemisphere, previously ...

plants in the

grass family Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

.Hitchcock, A. S. 1909. Catalogue of the Grasses of Cuba. Contributions from the United States National Herbarium 12(6): 183–258, vii–xi
''Alloteropsis'' on pages 210-211 The group is widely distributed in

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

parts of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, as well as on certain islands in the

Indian Indian or Indians may refer to: Associated with India * of or related to India ** Indian people ** Indian diaspora ** Languages of India ** Indian English, a dialect of the English language ** Indian cuisine Associated with indigenous peoples o ...

and

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

s. The genus is unusual among plants in that it includes species with both C₃ and C₄ photosynthetic pathways, and ongoing research is investigating these

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

as a case study in how carbon concentrating mechanisms for photosynthesis evolve in

land plants The embryophytes () are a clade of plants, also known as Embryophyta (Plantae ''sensu strictissimo'') () or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophy ...

.Ibrahim, D. G., et al. (2009)
A molecular phylogeny of the genus ''Alloteropsis'' (Panicoideae, Poaceae) suggests an evolutionary reversion from C₄ to C₃ photosynthesis.
''Annals of Botany'' 103(1): 127–136. .

Photosynthetic pathway evolution

Most of the species of ''Alloteropsis'' use variants of the C₄ photosynthetic pathway, but ''A. semialata'' ssp. ''eckloniana'' uses the C₃ photosynthetic pathway.

Phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

reconstructions of the evolutionary relationships between these species have led to two

hypotheses A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific method, scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educ ...

about how photosynthetic pathways have evolved within the group. First, C₄ photosynthesis evolved in three lineages within this group, leading to independently derived realisations of this pathway (the hypothesis of multiple C₄ origins).Christin, P., et al. (2010)
Can phylogenetics identify C4 origins and reversals?
''Trends in Ecology and Evolution'' 25(7): 403–09. Secondly, that there was a single origin of C₄ photosynthesis within the genus, and the C₃ taxon, ''A. s. ecklonia'', was subsequently derived from a C₄

ancestor An ancestor, also known as a forefather, fore-elder, or a forebear, is a parent or ( recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from ...

(the reversion hypothesis). Since C₄ photosynthesis is a complex trait, its evolution followed by a reversion to the ancestral type of C₃ photosynthesis would represent an exception to Dollo's law. The reversion hypothesis is the most

parsimonious In philosophy, Occam's razor (also spelled Ockham's razor or Ocham's razor; ) is the problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements. It is also known as the principle o ...

explanation of phylogenetic relationships within ''Alloteropsis''. However, direct evidence for the hypothesis, in the form of C₄

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s or

pseudogene Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Pseudogenes can be formed from both protein-coding genes and non-coding genes. In the case of protein-coding genes, most pseudogenes arise as superfluous copies of fun ...

s in the C₃ taxon, is currently lacking.Christin, P., et al. (2012)
Adaptive evolution of C₄ photosynthesis through recurrent lateral gene transfer.
''Current Biology'' 22(5): 445–49. . Instead, two pieces of evidence better support the hypothesis of multiple C₄ origins. First, different variants of C₄ leaf anatomy are found in three different ''Alloteropsis'' lineages. Secondly, key C₄ enzymes ( PEPC and

PEPCK Phosphoenolpyruvate carboxykinase (, PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. It is found in two forms, cytosolic and mitoc ...

) were recruited multiple times to function in C₄ biochemistry across independent lineages. C₄ photosynthetic pathway evolution in ''Alloteropsis'' also represents an example of

adaptive evolution In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

via

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s. It is the first such example of gene transfer between plant species that are not in direct physical contact (as in a host-parasite relationship). In each case, genes adapted for an important function in C₄ photosynthesis have been transferred from grass lineages that diverged from ''Alloteropsis'' more than 20 million years ago, and independently evolved C₄ photosynthesis. Horizontally inherited genes encode the photosynthesis

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s PEPC and PEPCK. All other genes expressed in the mature C₄ leaf of ''A. s. semialata'' were vertically inherited from a

common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...

with the C₃ taxon ''A. s. eckloniana''.

Diversity

; Accepted speciesKew World Checklist of Selected Plant Families
/ref> * '' Alloteropsis angusta'' Stapf -

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...

Zaire Zaire, officially the Republic of Zaire, was the name of the Democratic Republic of the Congo from 1971 to 18 May 1997. Located in Central Africa, it was, by area, the third-largest country in Africa after Sudan and Algeria, and the 11th-la ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

* '' Alloteropsis cimicina'' (L.) Stapf -

sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...

Indian Subcontinent The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian Ocean between the Bay of Bengal to the east and the Arabian Sea to the west. It is now divided between Bangladesh, India, and Pakista ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Hainan Hainan is an island provinces of China, province and the southernmost province of China. It consists of the eponymous Hainan Island and various smaller islands in the South China Sea under the province's administration. The name literally mean ...

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

, northern

; sparingly naturalized in scattered locations in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

(

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

).Biota of North America Program 2013 county distribution map, ''Alloteropsis cimicina''
/ref> * '' Alloteropsis paniculata'' (Benth.) Stapf - tropical

Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...

Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...

* '' Alloteropsis papillosa'' Clayton -

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

Limpopo Limpopo () is the northernmost Provinces of South Africa, province of South Africa. It is named after the Limpopo River, which forms the province's western and northern borders. The term Limpopo is derived from Rivombo (Livombo/Lebombo), a ...

Mpumalanga Mpumalanga () is one of the nine provinces of South Africa. The name means "East", or literally "The Place Where the Sun Rises" in the Nguni languages. Mpumalanga lies in eastern South Africa, bordering Eswatini and Mozambique. It shares bor ...

KwaZulu-Natal KwaZulu-Natal (, also referred to as KZN) is a Provinces of South Africa, province of South Africa that was created in 1994 when the government merged the Zulu people, Zulu bantustan of KwaZulu ("Place of the Zulu" in Zulu language, Zulu) and ...

* '' Alloteropsis semialata'' (R.Br.) Hitchc. -

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, northern

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

Solomon Islands Solomon Islands, also known simply as the Solomons,John Prados, ''Islands of Destiny'', Dutton Caliber, 2012, p,20 and passim is an island country consisting of six major islands and over 1000 smaller islands in Melanesia, part of Oceania, t ...

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

; Formerly included see '' Mayariochloa Scutachne'' * ''Alloteropsis amphistemon - Mayariochloa amphistemon'' * ''Alloteropsis dura - Scutachne dura''

References

External links

Grassbase - The World Online Grass Flora
{{Taxonbar, from=Q2675251 Poaceae genera Panicoideae

Photosynthetic pathway evolution

Diversity

See also

References

External links