The Ramphastos genus, also known as toucans, is a genus of brightly colored, tropical birds that are found throughout Central and South America from Southern Mexico to the southern cone of the South American continent. Toucans are typically characterized by their large, colorful bills, which are used for a variety of functions such as thermoregulation, feeding, and social signaling.
Taxonomy
The
genus Ramphastos was introduced in 1758 by the Swedish naturalist
Carl Linnaeus in the tenth edition of his
Systema Naturae.
The name is from
Ancient Greek ῥαμφηστης/
rhamphēstēs meaning "snouted" (from ῥαμφη/
rhampē meaning "bill").
The
type species was later designated by Nicholas Aylward Vigors as the white-throated toucan (
Ramphastos tucanus).
Species
The genus contains eight species:
The phylogenetic tree below shows the relationships among the Ramphastidae, according to a 2023 study by Ostrow et al.
Former species
Some authorities, either presently or formerly, recognize additional species or subspecies as species belonging to the genus
Ramphastos including:
-
Green aracari (as Ramphastos viridis)
-
Ivory-billed aracari (as Ramphastos Azara)
-
Black-necked aracari (as Ramphastos Aracari)
-
Black-necked aracari (atricollis) (as Ramphastos atricollis)
-
Collared aracari (as Ramphastos torquatus)
-
Saffron toucanet (as Ramphastos Bailloni)
Description
This genus comprises the largest toucans, ranging from in length.
[Short, L. L., & Horne, J. F. M. (2002). Toucans (Ramphastidae). pp. 220–272 in del Hoyo, J., Elliott, A., & Sargatal, J. eds. (2002). Handbook of the Birds of the World. Vol. 7 Jacamars to Woodpecker. Lynx Edicions, Barcelona. ] All have black wings, tails and thighs, but the colour of the remaining
plumage depends on the exact species involved.
===Diversity of bills===
Distribution and habitat
Toucans are found throughout Central and South America, from southern Mexico to northern Argentina. They inhabit a variety of ecosystems, including tropical rainforests, cloud forests, and savannas. Toucans are particularly abundant in the
Amazon basin, where they play an important ecological role as seed dispersers and predators.
Behavior and ecology
Breeding
They are
arboreal and nest in tree holes laying 2–4 white eggs.
Food and feeding
All the species are basically fruit-eating, but will take insects and other small prey.
[
]
Threats
The louse Austrophilopterus cancellosus is suspected to parasitize all species of Ramphastos toucans. Its presence has been confirmed on all species except the citron-throated toucan.[Price, Roger D. & Weckstein, Jason D. (2005). The genus Austrophilopterus Ewing (Phthiraptera: Philopteridae) from toucans, toucanets, and araçaris (Piciformes: Ramphastidae). Zootaxa 918: 1–18. PDF fulltext]
Evolution
Phylogenetics
The Phylogenetics relationships among toucans have been the subject of ongoing debate and research; in the past, the eight toucan species were classified into different subfamilies based on their bill size and shape. However, recent molecular studies have suggested that toucans are more closely related to Aracari and toucanets than previously thought. Several species have also been removed from the Ramphastos genus: Green aracari, Ivory-billed aracari, Black-necked aracari, Collared aracari, Saffron toucanet.
One such study published in the journal Molecular Phylogenetics and Evolution in 2015,
The Ramphastos genus is divided into two groups which differ in the shape of their bills and their vocalization patterns. These two groups are known colloquially as the “croakers'' and the “yelpers”. The “croakers'' contain the following: R. brevis, R. dicolorus, R. sulfuratus, R. toco, and R. vitellinus. The “yelper” group contains: R. ambiguous and R. tucanus. Of these, R. brevis and R. dicolorus are polytypic.
History
The evolutionary history of toucans can be traced back to the Eocene period, around 50 million years ago, the first toucan-like bird,may have appeared in Europe. The modern toucan species, however, originated in South America during the Miocene period, around 23 million years ago.
Transposable Elements
Transposable elements are a major source of genetic diversity and can contribute to the evolution of new genes and regulatory elements. Transposable elements have been found in the genomes of all organisms studied so far, including the Ramphastos genus.
One study published in the journal Genome Biology in 2018,
The researchers also identified several families of transposable elements that were specific to toucans, indicating that these elements had played a role in the evolution of the toucan genome. In particular, the researchers identified a family of elements called CR1, which had undergone a burst of activity in the toucan genome. This burst of activity was associated with the expansion and diversification of several gene families that are involved in sensory perception and immune response.
The study also found that transposable elements had contributed to the evolution of the toucan bill, which is one of the most distinctive features of toucans. The researchers identified several genes involved in the development of the bill that had been influenced by these elements. In particular, they found that they had inserted into regulatory regions of the genes, altering their expression patterns and contributing to the development of the large and colorful bill.
Notes
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