Gallotia
Encyclopedia
The genus
Gallotia are the lacertids (wall lizard
s) of the Canary Islands
. This genus
consists of a group that has been evolving
there ever since the first islands emerged from the sea over 20 million years ago. The endemic
species
and subspecies
of this group have a number of characteristics that make them quite special within their family
(Lacertidae
); their only close relatives are the sandrunner lizards (Psammodromus
) of the western Mediterranean region. Gallotia are characteristic for eating significant quantities of plants, and for several lineages having evolved insular gigantism.
lineages and a western clade
- based on mtDNA cytochrome b
and 12S rRNA sequence
analysis and agreeing with a common pattern of radiation in the Canarian archipelago
(Maca-Meyer et al. 2003). Both contain very large and small species.
The basal taxa cannot be resolved in their phylogenetic position to each other and the western clade. Given that G. atlantica is a small and G. stehlini a giant species, and that it is also not known when exactly the later evolved its large size, the ancestral lizards which colonized the central and western islands may have been still small or already large.
As the western clade contains a lineage of small and another one of larger species, size changed drastically at least twice in this genus. Moreover, it is not fully resolved in how far the western islands' giant species are related to each other either, as only limited material of G. auaritae has been available for phylogenetic analyses (Maca-Meyer et al. 2003).
Thus, there presently exists no satisfying, parsimonious model for evolution of giant size in this genus. In the western clade alone, giant size may be a plesiomorphy (and lost again in caesaris and galloti), a synapomorphy
(and lost again in intermedia), or several autapomorphies (evolving independently in goliath and the simonyi group) in regard to the ancestral lizards which colonized the western Canaries.
In any case, in historic and late prehistoric times the three westernmost islands (La Palma
, La Gomera
, and El Hierro
) and Gran Canaria
held one large and one small species. Tenerife
, largest of the islands, additionally has the appropriately-named intermedius, whereas before the modern introductions no large species were known to occur on the two easternmost islands (Lanzarote
and Fuerteventura
). It is well possible however that remains of extinct giant forms will eventually be discovered there too, given that the successful introduction of G. stehlini to Fuerteventura suggests a vacant ecological niche
was present there.
Prehistoric remains were assigned to the taxa G. goliath and G. maxima, the former supposedly occurring on several islands, the latter only on Tenerife
. It was eventually determined, however, that G. maxima is a junior synonym of G. goliath, and that the latter was very close to G. simonyi; supposed goliath specimens from El Hierro
, La Gomera
, and La Palma
are probably just extremely large individuals of, respectively, G. simonyi, G. bravoana, and G. auaritae (Barahona et al. 2000). However, a mummified giant specimen from Tenerife yielded ancient DNA
remains, and by analysis of this, it was concluded that G. goliath is a valid species that probably was restricted to Tenerife, and apparently was closer to G. intermedia than to G. simonyi (Maca-Meyer et al. 2003).
Basal group
Western clade
Large species
Small species
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...
Gallotia are the lacertids (wall lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s) of the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
. This genus
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...
consists of a group that has been evolving
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...
there ever since the first islands emerged from the sea over 20 million years ago. The endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to 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...
and subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of this group have a number of characteristics that make them quite special within their 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...
(Lacertidae
Lacertidae
Lacertidae is the family of the wall lizards, true lizards, or sometimes simply lacertas, which are native to Europe, Africa, and Asia. The group includes the genus Lacerta, which contains some of the most commonly seen lizard species in Europe...
); their only close relatives are the sandrunner lizards (Psammodromus
Psammodromus
Psammodromus is a small genus of sand lizards of the family Lacertidae. It has six described species, which are found in European and North African countries next to the Mediterranean.-Species:* Psammodromus algirus - Linnaeus, 1758...
) of the western Mediterranean region. Gallotia are characteristic for eating significant quantities of plants, and for several lineages having evolved insular gigantism.
Systematics and biogeography
This genus can be divided into two groups - basalBasal (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:...
lineages and a western clade
Clade
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...
- based on mtDNA 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 sequence
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...
analysis and agreeing with a common pattern of radiation in the Canarian archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
(Maca-Meyer et al. 2003). Both contain very large and small species.
The basal taxa cannot be resolved in their phylogenetic position to each other and the western clade. Given that G. atlantica is a small and G. stehlini a giant species, and that it is also not known when exactly the later evolved its large size, the ancestral lizards which colonized the central and western islands may have been still small or already large.
As the western clade contains a lineage of small and another one of larger species, size changed drastically at least twice in this genus. Moreover, it is not fully resolved in how far the western islands' giant species are related to each other either, as only limited material of G. auaritae has been available for phylogenetic analyses (Maca-Meyer et al. 2003).
Thus, there presently exists no satisfying, parsimonious model for evolution of giant size in this genus. In the western clade alone, giant size may be a plesiomorphy (and lost again in caesaris and galloti), a synapomorphy
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
(and lost again in intermedia), or several autapomorphies (evolving independently in goliath and the simonyi group) in regard to the ancestral lizards which colonized the western Canaries.
In any case, in historic and late prehistoric times the three westernmost islands (La Palma
La Palma
La Palma is the most north-westerly of the Canary Islands. La Palma has an area of 706 km2 making it the fifth largest of the seven main Canary Islands...
, La Gomera
La Gomera
La Gomera is one of Spain's Canary Islands, located in the Atlantic Ocean off the coast of Africa. In area, it is the second-smallest of the seven main islands of this group.- Political organization :...
, and El Hierro
El Hierro
El Hierro, nicknamed Isla del Meridiano , is the smallest and farthest south and west of the Canary Islands , in the Atlantic Ocean off the coast of Africa, with a population of 10,162 .- Name :The name El Hierro, although phonetically identical to the Spanish word for 'iron', is generally thought...
) and Gran Canaria
Gran Canaria
Gran Canaria is the second most populous island of the Canary Islands, with a population of 838,397 which constitutes approximately 40% of the population of the archipelago...
held one large and one small species. Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
, largest of the islands, additionally has the appropriately-named intermedius, whereas before the modern introductions no large species were known to occur on the two easternmost islands (Lanzarote
Lanzarote
Lanzarote , a Spanish island, is the easternmost of the autonomous Canary Islands, in the Atlantic Ocean, approximately 125 km off the coast of Africa and 1,000 km from the Iberian Peninsula. Covering 845.9 km2, it stands as the fourth largest of the islands...
and Fuerteventura
Fuerteventura
Fuerteventura , a Spanish island, is one of the Canary Islands, in the Atlantic Ocean off the coast of Africa. It is situated at 28°20' north, 14°00' west. At 1,660 km² it is the second largest of the Canary Islands, after Tenerife...
). It is well possible however that remains of extinct giant forms will eventually be discovered there too, given that the successful introduction of G. stehlini to Fuerteventura suggests a vacant ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
was present there.
Prehistoric remains were assigned to the taxa G. goliath and G. maxima, the former supposedly occurring on several islands, the latter only on Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
. It was eventually determined, however, that G. maxima is a junior synonym of G. goliath, and that the latter was very close to G. simonyi; supposed goliath specimens from El Hierro
El Hierro
El Hierro, nicknamed Isla del Meridiano , is the smallest and farthest south and west of the Canary Islands , in the Atlantic Ocean off the coast of Africa, with a population of 10,162 .- Name :The name El Hierro, although phonetically identical to the Spanish word for 'iron', is generally thought...
, La Gomera
La Gomera
La Gomera is one of Spain's Canary Islands, located in the Atlantic Ocean off the coast of Africa. In area, it is the second-smallest of the seven main islands of this group.- Political organization :...
, and La Palma
La Palma
La Palma is the most north-westerly of the Canary Islands. La Palma has an area of 706 km2 making it the fifth largest of the seven main Canary Islands...
are probably just extremely large individuals of, respectively, G. simonyi, G. bravoana, and G. auaritae (Barahona et al. 2000). However, a mummified giant specimen from Tenerife yielded ancient DNA
Ancient DNA
Ancient DNA is DNA isolated from ancient specimens. It can be also loosely described as any DNA recovered from biological samples that have not been preserved specifically for later DNA analyses...
remains, and by analysis of this, it was concluded that G. goliath is a valid species that probably was restricted to Tenerife, and apparently was closer to G. intermedia than to G. simonyi (Maca-Meyer et al. 2003).
| El Hierro | La Palma | La Gomera | Tenerife | Gran Canaria | Fuerteventura | Lanzarote | |
|---|---|---|---|---|---|---|---|
| Small | G. caesaris | G. galloti | G. caesaris | G. galloti | G. atlantica | G. atlantica | G. atlantica |
| Large | G. intermedia | ||||||
| Giant | G. simonyi | G. auaritae | G. bravoana | G. goliath | G. stehlini | G. stehlini |
Basal group
- Gallotia atlantica - Atlantic LizardAtlantic LizardThe Atlantic Lizard is a species of lizard in the Lacertidae family.It is endemic to Spain.Its natural habitats are temperate forests, temperate shrubland, Mediterranean-type shrubby vegetation, rocky areas, rocky shores, sandy shores, arable land, pastureland, and rural gardens.-References:*...
- Gallotia atlantica atlantica
- Gallotia atlantica delibesi
- Gallotia atlantica ibagnezi
- Gallotia atlantica laurae
- Gallotia atlantica mahoratae
- Gallotia stehlini - Gran Canaria Giant LizardGran Canaria Giant LizardThe Gran Canaria Giant Lizard is a species of lizard in the Lacertidae family that grows to lengths up to 80 cm. It is endemic to Gran Canaria in the Canary Islands of Spain....
Western clade
Large species
- Gallotia simonyi
- Gallotia simonyi simonyi - Roque Chico de Salmor Giant LizardRoque Chico de Salmor Giant LizardThe Roque Chico de Salmor Giant Lizard was the nominate subspecies of the lacertid Gallotia simonyi. It was once present on a small islet near El Hierro in the Canary Islands....
, extinct (c.1930s) - Gallotia simonyi machadoi - El Hierro Giant LizardEl Hierro Giant LizardGallotia simonyi is a species of lacertid that can be found on the island of El Hierro, one of the Canary Islands. The species was once present throughout much of the island and on the small offshore Roque Chico de Salmor, but is now confined to a few small areas of cliff with sparse vegetation...
- Gallotia simonyi simonyi - Roque Chico de Salmor Giant Lizard
- Gallotia bravoana - La Gomera Giant LizardLa Gomera Giant LizardThe La Gomera Giant Lizard is a lacertid species that can be found on the island of La Gomera, one of the Canary Islands....
, formerly G. (simonyi) gomerana and G. simonyi bravoana (Miras & Pérez-Mellado 2005a) - Gallotia auaritae - La Palma Giant LizardLa Palma Giant LizardThe La Palma Giant Lizard is a giant lacertid historically living in the island of La Palma ; its habitat ranged from sea level up to altitudes of 800 m....
- Gallotia goliath - Tenerife Giant LizardGallotia goliathGallotia goliath is an extinct giant lizard species from the island of Tenerife of the Canary Islands, Spain. This reptile lived before the arrival of humans. It was described by the German herpetologist Robert Mertens. It is believed that it grew to at least three feet long...
, subfossilSubfossilSubfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
; includes G. maxima - Gallotia intermedia - Tenerife Speckled LizardTenerife Speckled LizardThe Tenerife Speckled Lizard, Gallotia intermedia, is a recently-discovered lacertid of Tenerife in the Canary Islands...
Small species
- Gallotia caesaris - Boettger's LizardBoettger's LizardBoettger's Lizard is a lacertid endemic to two of the western Canary Islands, El Hierro and La Gomera. On the neighboring islands Tenerife and La Palma it is replaced by its close relative Gallotia galloti...
- Gallotia caesaris caesaris
- Gallotia caesaris gomerae
- Gallotia galloti - Tenerife Lizard or Western Canaries Lizard
- Gallotia galloti eisentrauti
- Gallotia galloti galloti
- Gallotia galloti insulanagae
- Gallotia galloti palmae