Gallotia

Taxobox
name = "Gallotia"

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image_width = 250px
image_caption = Tenerife Lizard ("Gallotia galloti galloti") male (top) and female
regnum = Animalia
phylum = Chordata
classis = Reptilia
ordo = Squamata
familia = Lacertidae
subfamilia = Gallotiinae
genus = "Gallotia"
genus_authority = Boulenger, 1916
subdivision_ranks = Species
subdivision =
*"Gallotia atlantica"
*"Gallotia auaritae"
*"Gallotia bravoana"
*"Gallotia caesaris"
*"Gallotia galloti"
*"Gallotia goliath" (subfossil)
*"Gallotia intermedia"
*"Gallotia simonyi"
**"Gallotia simonyi simonyi" (extinct)
**"Gallotia simonyi machadoi"
*"Gallotia stehlini"

The genus "Gallotia" are the lacertids (wall lizards) 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.

ystematics and biogeography

This genus can be divided into two groups - basal 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 [See p.665. The presumption of a fixed-speed molecular clock (p.667) - which furthermore implies lack of genetic drift - is unrealistic.] ).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).

Note: "G. auaritae" was rediscovered in 2007, but remains classified as extinct until the Red List is updated.

Basal group
*"Gallotia atlantica" - Atlantic Lizard
**"Gallotia atlantica atlantica"
**"Gallotia atlantica delibesi"
**"Gallotia atlantica ibagnezi"
**"Gallotia atlantica laurae"
**"Gallotia atlantica mahoratae"Verify source|date=July 2007
*"Gallotia stehlini" - Gran Canaria Giant Lizard

Western clade
Large species
*"Gallotia simonyi"
**"Gallotia simonyi simonyi" - Roque Chico de Salmor Giant Lizard, extinct (c.1930s)
**"Gallotia simonyi machadoi" - El Hierro Giant Lizard
*"Gallotia bravoana" - La Gomera Giant Lizard, formerly "G. (simonyi) gomerana" and "G. simonyi bravoana" (Miras & Pérez-Mellado 2005a)
*"Gallotia auaritae" - La Palma Giant Lizard
*"Gallotia goliath" - Tenerife Giant Lizard, subfossil; includes "G. maxima"
*"Gallotia intermedia" - Tenerife Speckled LizardSmall species
*"Gallotia caesaris" - Boettger's Lizard
**"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"

References

* Barahona, F.; Evans, S. E.; Mateo, J.A.; García-Márquez, M. & López-Jurado, L.F. (2000): Endemism, gigantism and extinction in island lizards: the genus "Gallotia" on the Canary Islands. "J. Zool." 250(3): 373-388. doi|10.1017/S0952836900003101 (HTML abstract)

* European Environment Agency (2006) [http://eunis.eea.europa.eu/ European Nature Information System (EUNIS)] : "Gallotia". Downloaded on 18 May 2006.

* Filson, R.P. (2000): [http://www.ucmp.berkeley.edu/fosrec/Filson.html Island Biogeography and Evolution: Solving a Phylogenetic Puzzle Using Molecular Genetics] . Downloaded on 11 May 2006.

* Maca-Meyer, N.; Carranza, S.; Rando, J.C.; Arnold, E.N. & Cabrera, V.M. (2003): Status and relationships of the extinct giant Canary Island lizard "Gallotia goliath" (Reptilia: Lacertidae), assessed using ancient mtDNA from its mummified remains. "Biol. J. Linn. Soc." 80(4): 659–670. DOI|10.1111/j.1095-8312.2003.00265.x (HTML abstract)

* Database entry includes a range map and a brief justification of why this species is listed as extinct

* Database entry includes a range map and justification for why this species is critically endangered

* Database entry includes a range map and justification for why this species is critically endangered

* Database entry includes a range map and justification for why this species is critically endangered

Footnotes