Raphidae
Encyclopedia
The Raphinae are a subfamily of extinct flightless bird
s colloquially called didines or didine birds. They inhabited the Mascarene Islands
of Mauritius
and Rodrigues
, but became extinct through hunting by humans and predation by introduced non-native mammal
s following human colonisation in the 17th century.
is part of the order
Columbiformes
and contains the monotypic
genera
Pezophaps and Raphus. The former contains the species
Pezophaps solitaria (the Rodrigues Solitaire
), the latter the Dodo
, Raphus cucullatus. These birds reached an impressive size as a result of isolation on predatorless islands in accordance with Foster's rule
.
The "Réunion Solitaire
", long considered a third extinct didine bird, has turned out to be an ibis
; it is now known as Threskiornis solitarius.
The didines are often separated as a distinct family
Raphidae, and their affinities were for long uncertain; they were initially placed within the ratite
s due to their peculiar, flightlessness-related apomorphies, and a relationship to the Rallidae
has also been suggested. Osteological
and molecular data, however, agrees that placement in the Columbidae is more appropriate.
Comparison of mitochondrial cytochrome b
and 12S rRNA sequences
suggests the Nicobar Pigeon
(Caloenas nicobarica) is the closest living relative of the Dodo
and the Rodrigues Solitaire
. This does not actually imply a very close relationship, however, and at any rate, the molecular phylogeny
of the Indo-Australian pigeons has yielded wildly differing results depending on the gene sequence analyzed.
What appears certain, regardless of the closest living relative of the didines, is that they belong to a basal
Indo-Australian radiation
of pigeons. Apart from the didines, this includes such animals as the Goura
crowned pigeons, the Pheasant Pigeon
, Ducula
and Ptilinopus, and the Nicobar Pigeon. Accordingly, until better material evidence of the didines' ancestry is available, they are here considered a subfamily of the Columbidae.
No good data is available for dating the group's evolution
. Based on the data analyzed by Shapiro et al., they gave an estimate of 32–56 mya for the didine-Caloenas divergence. This may or may not be roughly correct; the more precise date of c.43 mya most likely is not since the molecular clock
was calibrated with a presumed penguin
—Procellariiformes
divergence that has since been invalidated by Waimanu
. It is far more likely than not, however, that this group's origin lay in the Paleogene
than in the Neogene
, as indicated by the paleogeography of the W Indian Ocean
area, notably the Mascarene Plateau
. This would support the view that the Columbidae are among the older landbird lineages among the Neoaves.
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
s colloquially called didines or didine birds. They inhabited the Mascarene Islands
Mascarene Islands
The Mascarene Islands is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks...
of Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
and Rodrigues
Rodrigues (island)
Rodrigues , sometimes spelled Rodriguez but named after the Portuguese explorer Diogo Rodrigues, is the smallest of the Mascarene Islands and a dependency of Mauritius...
, but became extinct through hunting by humans and predation by introduced non-native mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s following human colonisation in the 17th century.
Overview
This cladeClade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
is part of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Columbiformes
Columbiformes
Columbiformes are an avian order that includes the very widespread and successful doves and pigeons, classified in the family Columbidae, and the extinct Dodo and the Rodrigues Solitaire, long classified as a second family Raphidae. 313 species, found worldwide, comprise the Columbiformes order....
and contains the monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Pezophaps and Raphus. The former contains the 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...
Pezophaps solitaria (the Rodrigues Solitaire
Rodrigues Solitaire
The Rodrigues Solitaire was a flightless member of the pigeon order endemic to Rodrigues, Mauritius. It was a close relative of the Dodo.-Discovery:...
), the latter the Dodo
Dodo
The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....
, Raphus cucullatus. These birds reached an impressive size as a result of isolation on predatorless islands in accordance with Foster's rule
Foster's rule
Foster's rule is a principle in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. This is the core of the study of island biogeography. For example, it is known that pygmy mammoths evolved from normal mammoths on...
.
The "Réunion Solitaire
Réunion Sacred Ibis
The Réunion Sacred Ibis, Threskiornis solitarius, is an extinct bird species that was native to the island of Réunion. It is probably the same bird discovered by Portuguese sailors there in 1613...
", long considered a third extinct didine bird, has turned out to be an ibis
Ibis
The ibises are a group of long-legged wading birds in the family Threskiornithidae....
; it is now known as Threskiornis solitarius.
The didines are often separated as a distinct family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Raphidae, and their affinities were for long uncertain; they were initially placed within the ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...
s due to their peculiar, flightlessness-related apomorphies, and a relationship to the Rallidae
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
has also been suggested. Osteological
Osteology
Osteology is the scientific study of bones. A subdiscipline of anatomy, anthropology, and archeology, osteology is a detailed study of the structure of bones, skeletal elements, teeth, morphology, function, disease, pathology, the process of ossification , the resistance and hardness of bones , etc...
and molecular data, however, agrees that placement in the Columbidae is more appropriate.
Comparison of mitochondrial cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
and 12S rRNA sequences
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
suggests the Nicobar Pigeon
Nicobar Pigeon
The Nicobar Pigeon, Caloenas nicobarica, is a pigeon found on small islands and in coastal regions from the Nicobar Islands, east through the Malay Archipelago, to the Solomons and Palau. It is the only living member of the genus Caloenas....
(Caloenas nicobarica) is the closest living relative of the Dodo
Dodo
The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....
and the Rodrigues Solitaire
Rodrigues Solitaire
The Rodrigues Solitaire was a flightless member of the pigeon order endemic to Rodrigues, Mauritius. It was a close relative of the Dodo.-Discovery:...
. This does not actually imply a very close relationship, however, and at any rate, the molecular phylogeny
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
of the Indo-Australian pigeons has yielded wildly differing results depending on the gene sequence analyzed.
What appears certain, regardless of the closest living relative of the didines, is that they belong to a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
Indo-Australian radiation
Adaptive radiation
In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...
of pigeons. Apart from the didines, this includes such animals as the Goura
Goura
Goura may refer to:* Goura , a genus of doves* Goura, Corinthia, a village in Greece* Goura, Phocis, a village in Greece* Goura, Cameroon, a place in Centre Province, Cameroon* Goura , a mouth-blown stringed musical instrument...
crowned pigeons, the Pheasant Pigeon
Pheasant Pigeon
The Pheasant Pigeon is a large terrestrial pigeon found in the primary rainforests of New Guinea and nearby islands. It ranges primarily over hilly and lower mountain areas, but can also be found in lowlands....
, Ducula
Ducula
Ducula is a genus of bird in the pigeon family Columbidae; these pigeons are very large and are called imperial pigeons. Most imperial pigeon species show contrasting light coloration of the head, neck, and belly with darker back and wings...
and Ptilinopus, and the Nicobar Pigeon. Accordingly, until better material evidence of the didines' ancestry is available, they are here considered a subfamily of the Columbidae.
No good data is available for dating the group's evolution
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...
. Based on the data analyzed by Shapiro et al., they gave an estimate of 32–56 mya for the didine-Caloenas divergence. This may or may not be roughly correct; the more precise date of c.43 mya most likely is not since the molecular clock
Molecular clock
The molecular clock is a technique in molecular evolution that uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation...
was calibrated with a presumed penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
—Procellariiformes
Procellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...
divergence that has since been invalidated by Waimanu
Waimanu
Waimanu is a genus of early penguin which lived soon after the Cretaceous-Paleogene extinction event. Its discovery helped support the idea that the radiation of the Neoaves either took place before the extinction of the dinosaurs, or that it must have been extremely rapid in geological terms...
. It is far more likely than not, however, that this group's origin lay in the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
than in the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
, as indicated by the paleogeography of the W Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
area, notably the Mascarene Plateau
Mascarene Plateau
The Mascarene Plateau is an submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately 2000 km, from the Seychelles in the north to Réunion in the south. The plateau covers an area of over 115,000 km² of shallow water, with depths ranging from...
. This would support the view that the Columbidae are among the older landbird lineages among the Neoaves.