Mountain-gem
Encyclopedia
The mountain-gems are the Lampornis genus
of hummingbird
s which inhabit mountainous regions from the southwestern United States
to the Isthmus of Panama
.
These are medium-sized to large (10–13 cm) hummingbirds with shortish slightly curved black bills. The males typically have green upperparts and a brightly coloured throat, which is a dull colour in the female. The females of some species also may differ significantly from the males in other plumage features.
The female mountain-gem is entirely responsible for nest building and incubation. She lays two white eggs in a deep plant-fibre cup nest. Incubation takes 15–19 days, and fledging another 20-26.
The food of this genus is nectar, taken from a variety of small flowers. Like other hummingbirds, mountain-gems also takes small insects as an essential source of protein.
over Costa Rica
to Panama
, are one ("Variable Mountain-gem"), two or three species. Analysis of biogeography
and mitochondrial and nuclear DNA
sequences
by García-Moreno et al. (2006) have largely confirmed the arrangement and the suspected evolution
ary relationships, but a few surprising results have emerged:
First, the White-throated Mountain-gem
and the Gray-tailed Mountain-gem
are probably conspecific, but the Purple-throated Mountain-gem
seems to be a distinct species. However, the southern group has apparently evolved in a very short time and their conspicuous differences in appearance are not yet reflected in molecular divergence; as mates are of course chosen according to their appearance and not their molecular differences, it seems prudent to split the group according to throat color as advocated by the American Ornithologists' Union
. However, the speciation
process is ongoing.
Second, the exact relationship between the suspected sister taxa L. clemenciae and L. amethystinus, the northernmost species, is not as straightforward as assumed; it is not clear whether they are each other's close relatives or whether the Blue-throated Hummingbird
is the oldest lineage of the genus, the Amethyst-throated Hummingbird
diverging later. In addition, L. amethystinus may constitute two species, but not the violet-throated subspecies margaritae but the southernmost, red-throated forms are the most distinct ones.
Most puzzling, however, is the fact that the White-bellied Mountain-gem
constantly failed to form a monophyletic group with the other taxa. These results suggest that it is better placed in the monotypic
genus Oreopyra, the relationships of which need more study. It might be closely related to the Fiery-throated Hummingbird
, but these two species are very different at least morphologically. The Garnet-throated Hummingbird
, which is sometimes considered to be the closest relative of the mountain-gems, is indeed not distantly related to the group, but closer to the Magnificent Hummingbird
. It is intermediate in appearance between Lampornis and that species.
García-Moreno's team refrains to date the emergence of the genus because of the absence of fossils or other robust evidence. It can be assumed though that Lampornis was present at the closing of the Isthmus of Panama, about 3.8 MYA, and that by that time, the northernmost lineage(s) had already diverged.
These results are interesting, because they agree with a general trend for southern Mexican taxa (including to colonize the Isthmus and there form distinct species. Also, the Isthmus group of Lampornis provides a glimpse at an intermediate stage in evolution, with one form (L. calolaema) having recently evolved into a distinct species, while its white-throated relatives are in the process of splitting into two species but have not yet done so. mtDNA (which is inherited from the mother only) suggests that the Purple-throated Mountain-gem
still can form fertile hybrids with the white-throated forms and indeed not infrequently does so.
According to the updated taxonomy, the species are:
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...
of hummingbird
Hummingbird
Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s which inhabit mountainous regions from the southwestern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
to the Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...
.
These are medium-sized to large (10–13 cm) hummingbirds with shortish slightly curved black bills. The males typically have green upperparts and a brightly coloured throat, which is a dull colour in the female. The females of some species also may differ significantly from the males in other plumage features.
The female mountain-gem is entirely responsible for nest building and incubation. She lays two white eggs in a deep plant-fibre cup nest. Incubation takes 15–19 days, and fledging another 20-26.
The food of this genus is nectar, taken from a variety of small flowers. Like other hummingbirds, mountain-gems also takes small insects as an essential source of protein.
Systematics
6-8 species have been traditionally recognized, the main point of dispute being whether the southern forms, of the mountain range from NicaraguaNicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...
over Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
to Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
, are one ("Variable Mountain-gem"), two or three species. Analysis of biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
and mitochondrial and nuclear DNA
Nuclear DNA
Nuclear DNA, nuclear deoxyribonucleic acid , is DNA contained within a nucleus of eukaryotic organisms. In mammals and vertebrates, nuclear DNA encodes more of the genome than the mitochondrial DNA and is composed of information inherited from two parents, one male, and one female, rather than...
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...
by García-Moreno et al. (2006) have largely confirmed the arrangement and the suspected 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...
ary relationships, but a few surprising results have emerged:
First, the White-throated Mountain-gem
White-throated Mountain-gem
The White-throated Mountaingem is a hummingbird which breeds in the mountains of western Panama. It is replaced in southern Costa Rica by a distinct subspecies, the Gray-tailed Mountaingem, L. castaneoventris cinereicauda, which is very close to becoming a distinct species...
and the Gray-tailed Mountain-gem
Gray-tailed Mountain-gem
The Grey-tailed Mountaingem or Gray-tailed Mountaingem is a hummingbird which breeds only in the mountains of southern Costa Rica...
are probably conspecific, but the Purple-throated Mountain-gem
Purple-throated Mountain-gem
The Purple-throated Mountaingem is a hummingbird which breeds in the mountains of southern Nicaragua, northern Costa Rica and western Panama...
seems to be a distinct species. However, the southern group has apparently evolved in a very short time and their conspicuous differences in appearance are not yet reflected in molecular divergence; as mates are of course chosen according to their appearance and not their molecular differences, it seems prudent to split the group according to throat color as advocated by the American Ornithologists' Union
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
. However, the speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
process is ongoing.
Second, the exact relationship between the suspected sister taxa L. clemenciae and L. amethystinus, the northernmost species, is not as straightforward as assumed; it is not clear whether they are each other's close relatives or whether the Blue-throated Hummingbird
Blue-throated Hummingbird
The Blue-throated Mountaingem or Blue-Throated Hummingbird, Lampornis clemenciae, is a species of hummingbird, a member of the Trochilidae family of birds....
is the oldest lineage of the genus, the Amethyst-throated Hummingbird
Amethyst-throated Hummingbird
The Amethyst-Throated Mountaingem or Amethyst-Throated Hummingbird is a species of hummingbird in the Trochilidae family.It is found in El Salvador, Guatemala, Honduras, and Mexico....
diverging later. In addition, L. amethystinus may constitute two species, but not the violet-throated subspecies margaritae but the southernmost, red-throated forms are the most distinct ones.
Most puzzling, however, is the fact that the White-bellied Mountain-gem
White-bellied Mountain-gem
The White-bellied Mountaingem is a species of hummingbird in the Trochilidae family. It is found in Costa Rica and Panama.Its natural habitat is subtropical or tropical moist montanes.-References:...
constantly failed to form a monophyletic group with the other taxa. These results suggest that it is better placed in 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...
genus Oreopyra, the relationships of which need more study. It might be closely related to the Fiery-throated Hummingbird
Fiery-throated Hummingbird
The Fiery-throated Hummingbird is a medium-sized hummingbird which breeds only in the mountains of Costa Rica and western Panama...
, but these two species are very different at least morphologically. The Garnet-throated Hummingbird
Garnet-throated Hummingbird
The Garnet-throated Hummingbird is a species of hummingbird in the Trochilidae family. It is found in El Salvador, Guatemala, Honduras, and Mexico. It is in the monotypical genus Lamprolaima....
, which is sometimes considered to be the closest relative of the mountain-gems, is indeed not distantly related to the group, but closer to the Magnificent Hummingbird
Magnificent Hummingbird
The Magnificent Hummingbird is a large hummingbird that breeds in mountains from the southwestern United States to western Panama. It is the only member of the genus Eugenes, although the northern, nominate subspecies E. fulgens fulgens has on occasion been separated from the larger, southern race...
. It is intermediate in appearance between Lampornis and that species.
García-Moreno's team refrains to date the emergence of the genus because of the absence of fossils or other robust evidence. It can be assumed though that Lampornis was present at the closing of the Isthmus of Panama, about 3.8 MYA, and that by that time, the northernmost lineage(s) had already diverged.
These results are interesting, because they agree with a general trend for southern Mexican taxa (including to colonize the Isthmus and there form distinct species. Also, the Isthmus group of Lampornis provides a glimpse at an intermediate stage in evolution, with one form (L. calolaema) having recently evolved into a distinct species, while its white-throated relatives are in the process of splitting into two species but have not yet done so. mtDNA (which is inherited from the mother only) suggests that the Purple-throated Mountain-gem
Purple-throated Mountain-gem
The Purple-throated Mountaingem is a hummingbird which breeds in the mountains of southern Nicaragua, northern Costa Rica and western Panama...
still can form fertile hybrids with the white-throated forms and indeed not infrequently does so.
According to the updated taxonomy, the species are:
- Blue-throated Mountaingem, Lampornis clemenciae
- Amethyst-throated Mountaingem, Lampornis amethystinus
- Red-throated Mountangem, Lampornis (amethystinus) salvini
- Green-throated Mountaingem, Lampornis viridipallens
- Green-breasted Mountaingem, Lampornis sybillae
- Purple-throated Mountaingem, Lampornis calolaemus
- White-throated Mountaingem, Lampornis castaneoventris
- Gray-tailed Mountaingem, Lampornis castaneoventris cinereicauda
- White-bellied Mountaingem, Oreopyra hemileucus (formerly Lampornis)