Anolis extremus (Barbados anole)

Pictures

Picture	Title	Caption	Copyright
Title Adult Caption Anolis extremus (Barbados anole); adult. Barbados Wildlife Reserve, Barbados. February 2010. Copyright ©Postdlf/via wikipedia - CC BY-SA 3.0	Adult	Anolis extremus (Barbados anole); adult. Barbados Wildlife Reserve, Barbados. February 2010.	©Postdlf/via wikipedia - CC BY-SA 3.0
Title Adult Caption Anolis extremus (Barbados anole); adult. Barbados Wildlife Reserve, Barbados. February 2010. Copyright ©Postdlf/via wikipedia - CC BY-SA 3.0	Adult	Anolis extremus (Barbados anole); adult. Barbados Wildlife Reserve, Barbados. February 2010.	©Postdlf/via wikipedia - CC BY-SA 3.0
Title Adult Caption Anolis extremus (Barbados anole); adult, close-up of head. Barbados Wildlife Reserve, Barbados. February 2010. Copyright ©Postdlf/via wikipedia - CC BY-SA 3.0	Adult	Anolis extremus (Barbados anole); adult, close-up of head. Barbados Wildlife Reserve, Barbados. February 2010.	©Postdlf/via wikipedia - CC BY-SA 3.0

Identity

Preferred Scientific Name

• Anolis extremus Garman, 1887

Preferred Common Name

• Barbados anole

Other Scientific Names

• Anolis extremus Schwartz and Henderson 1991
• Anolis roquet extremus Grant, 1959
• Dactyloa extrema Nicholson et al., 2012

Local Common Names

• Barbados: cock lizard (adult males only); green lizard; tree lizard
• Saint Lucia: zanndoli

Summary of Invasiveness

A. extremus is a medium-sized anole lizard native to Barbados, where it is found in most terrestrial habitats apart from grassland. There are six known introductions, two of which in Trinidad and Tobago are no longer present, and one in Florida could not be confirmed. Introductions to Venezuela, Bermuda and St. Lucia are all confined to disturbed or urban and suburban habitats, and the species is not considered as invasive, except in some of the urban and suburban areas of St. Lucia where it has replaced the native A. luciae. In its native Barbados A. extremus remains abundant and is not threatened.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Chordata
•             Subphylum: Vertebrata
•                 Class: Reptilia
•                     Order: Sauria
•                         Family: Iguanidae
•                             Genus: Anolis
•                                 Species: Anolis extremus

Notes on Taxonomy and Nomenclature

The proposal to place A. extremus in the new genus Dactyloa was refuted by Poe (2013). A. extremus is part of the roquet group of Anolis of the southern Lesser Antilles (Yang et al., 1974). There are no subspecies recognized. The common name in its native Barbados is green lizard or tree lizard (Fields and Horrocks, 2011), and the adult males may also be known as cock lizards (Fields and Horrocks, 2009); outside its native island it is known as the Barbados anole. The common names zanndoli and extreme anole are also reported on St Lucia; zanndoli is a general name applied to all three Anolis species on the island (Daltry, 2009).

Description

A. extremus is a medium-sized anole (Anolis lizard), snout-vent (body excluding tail) length up to 83 mm in males and 60 mm in females. Males mossy green, anterior trunk with dark brown to black markings, with or without small pale spots. Head with blue-grey or lavender. Underside yellow, dewlap orange with yellow to greenish scales. Females olive green, duller than males, and may have striped middorsal pattern (Schwartz and Henderson, 1991). Lazell (1972) and Schwartz and Henderson (1991) give diagnostic details of scalation. Lazell (1972) designated MCZ 6183 (Museum of Comparative Zoology, Harvard; Garman collection) as the type specimen.

Distribution

It is widespread in its native Barbados, where it is found in most terrestrial habitats apart from grassland (Fields and Horrocks, 2011). There have been no attempts to locate the area of origin of any of the introduced populations, whether direct from Barbados or secondarily from other introduced populations.

Losos (1996) and Daltry (2009) provide the latest available maps of the distribution of the introduced populations of A. extremus in Bermuda and St Lucia, respectively. None of the other introduced populations have been mapped.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

There have been at least five introductions of A. extremus, to four countries (Lever, 2003; Kraus, 2008).

In Bermuda A. extremus was first observed in 1953 (Wingate, 1965), apparently introduced via ships using the naval dockyard in the period 1940-1945 (Lever, 2003). It had not spread much further by 1974 (Roughgarden, 1992), and was still limited to an area of a few square km in 1991 (Losos, 1996; Bacon et al., 2006). This contrasts with another introduced species, A. grahami, which is found throughout Bermuda (Losos, 1996). A. extremus is regarded as firmly established but non-invasive in Bermuda.

In St. Lucia A. extremus was first observed in 1956, and by 1976 there was already an abundant, well-established population extending between Castries and Vigie, in the northwest of the island (Gorman, 1976). Sampling in 2009 showed that it had extended its range to an area of about 15 square km, but the species is still localized and confined to urban and suburban areas. Daltry (2009) recorded A. extremus in only one out of 55 forest plots sampled (near Vigie airport), compared to 51 plots for the native A. luciae, accounting for 3 and 507 individuals, respectively. There has thus been little penetration into natural habitats in the first 50 years of this introduction. Daltry (2009) describes the invasion of A. extremus in St Lucia and its implications for conservation in some detail.

In Venezuela A. extremus was first reported based on a personal communication to J. Peters (Peters and Donoso-Barros, 1970) in Caracas. Subsequently museum specimens from Caracas have been confirmed, and the species was observed in eastern Caracas in 2011 (Rivas et al., 2012). It is regarded as established, but localized and non-invasive.

Two introduced populations of A. extremus to Trinidad and Tobago have both become extinct. Boos (1967) introduced six pairs to Huevos Island (off Trinidad) in 1965 as an experiment, and at least two individuals were still present in 1976 (Boos, 1978), although neither Boos (1996) nor Charles and Smith (2008) subsequently found the species there. A second introduction was around the Holiday Inn hotel on Wrightson Road, Port of Spain, in 1982 (Murphy, 1997). This is said to have originated from lizards released by a collector who was in transit from Barbados to another location (JC Murphy, personal communication). This population was extinct by 2004, and A. extremus is no longer considered to be present in Trinidad and Tobago (Hailey et al., 2009).

A reported sighting in the USA, from 1991-1994 around the Fort Myers Country Club, Lee County, Florida, by Bartlett and Bartlett (1998), and subsequently referred to by Meshaka et al. (2004), is unsubstantiated. The most recent survey of introduced herpetofauna in Florida (Krysko et al., 2011), and the State currently considers it as not confirmed to be breeding, if still present (Florida Fish and Wildlife Conservation Commission, 2013). Allen et al. (2013, Appendix S2, Herpetofauna introduced into peninsular Florida before 2001) consider A. extremus a failed introduction to Florida.

Introductions

Risk of Introduction

There is no significant commercial trade in A. extremus as pets, at least into or through the USA (Powell et al., 2011). There is always some risk of further introductions to the wider Caribbean region via the horticultural trade or shipping, either from Barbados or from the introduced populations in the ports on Bermuda and St Lucia.

Habitat

Native populations occupy most terrestrial habitats, such as woodlands, gullies and residential areas, but not grassland (Fields and Horrocks, 2011). Introduced populations have been restricted to urban and suburban habitats in all areas, with limited spread into adjoining forest in St. Lucia (Daltry, 2009). 

Habitat List

Biology and Ecology

Genetics

A. extremus shows a genetic divergence of the mitochondrial cytochrome b gene of 8.3% from the sister species A. roquet from Martinique (Thorpe et al., 2005). That is a much greater degree of divergence than predicted from the molecular clock for this gene, and the proposed geological time of emergence of Barbados, and suggests either more rapid divergence between these two species, or an earlier time of emergence of Barbados.

Gorman et al. (1978) used electrophoresis to compare heterozygosity of introduced and native populations of A. extremus on Bermuda, St Lucia and Barbados. All introduced populations had fewer polymorphic loci and lower heterozygosity than native populations. This indicates loss of genetic variability during the introduction process, presumably due to a founder effect.

Giannasi et al. (1997) investigated possible hybridisation between A. extremus and other anoles on St Lucia, but found no evidence for this.

Reproductive Biology

All female anoles lay a clutch of a single egg, often at intervals of only 1-2 weeks in productive habitats (Andrews and Rand, 1974). A. extremus breeds year round on Barbados, with peak reproduction rate in the rainy season (Nummelin, 1992).

Physiology and Phenology

Minimum size (snout-vent length) of mature individuals 46 mm in males and 42 mm in females (Lazell, 1972).

Longevity

No specific information. As a medium-sized anole, a life expectancy of around two years is likely (Losos, 2009).

Activity Patterns

A. extremus is active throughout the year and does not hibernate or aestivate. In Barbados they are mostly seen in trees, on the trunk and on larger branches in the canopy, on low shrubs, on walls of buildings, fences and on the ground (Fields and Horrocks, 2009). Juveniles are commonly found amid forest floor vegetation (Nummelin, 1992). The headbob display behaviour has apparently changed in the introduced population on Bermuda compared to the native population on Barbados, although this observation has not been statistically confirmed (Macedonia and Clark, 2003).

Population Size and Structure

Exceedingly abundant all over Barbados, with an apparently balanced sex ratio (Lazell, 1972). No density estimates are available.

Nutrition

Feeds on ants, spiders, cockroaches, grasshoppers, insect larvae and occasionally fruit (Daltry, 2009).

Host Associations

Staats and Schall (1996) and Schall and Staats (1997) examined the blood of 28 A. extremus from Barbados but found no Plasmodium or haemogregarine parasites. Gastrointestinal helminths have been recorded in A. extremus introduced in Bermuda (Goldberg et al., 1995). Poulin et al. (2003) noted three species of metazoan parasites in a sample of 10 A. extremus, but without giving details of taxa or location involved. Goldberg et al. (1997) found the oxyurid nematode Parapharyngodon cubensis in A. extremus, but the location of the A. extremus is unknown (information from Bursey et al., 2012).

Environmental Requirements

In Bermuda A. extremus prefers cooler areas than another introduced species, A. grahami (Schoener, 1970; Losos, 1996). These two species are otherwise similar in body size and habitat requirements, and show interspecific aggressive behavioural interactions (Losos, 1996).

Climate

Latitude/Altitude

Natural Enemies

Notes on Natural Enemies

On Barbados it is preyed upon by mongooses (Herpestes javanicus), green herons (Butorides virescens), cattle egrets (Bubulcus ibis), Carib grackles (Quiscalus lugubris), the grey kingbird (Tyrannus dominicensis), the centipede Scolopendra subspinipes, and domestic cats (Fields and Horrocks, 2009).

Means of Movement and Dispersal

Natural Dispersal

Not known.

Vector Transmission (Biotic)

Not known or likely.

Accidental Introduction

Most likely on horticultural produce, nursery plants, building materials or general shipping, or escaped pets.

Intentional Introduction

The introduction of six pairs of A. extremus on Huevos Island, Trinidad, by Boos in 1965 (Boos, 1967) was deliberate, as an experiment by the curator of the local zoological gardens. The population persisted for about a decade (Boos, 1978) but then became extinct (Boos, 1996; Hailey et al., 2009).

Pathway Causes

Pathway Vectors

Environmental Impact

Impact on Biodiversity

Replacement of or addition to other Anolis species is the only likely impact of introduced A. extremus. Giannasi et al. (1997) investigated possible hybridization between A. extremus and the native A. luciae on St Lucia, but found no evidence for this.

Environmental Services

Minor level of insect control.

Threatened Species

Risk and Impact Factors

Impact mechanisms

• Competition - monopolizing resources
• Interaction with other invasive species

Impact outcomes

• Changed gene pool/ selective loss of genotypes
• Conflict
• Reduced native biodiversity
• Threat to/ loss of native species

Invasiveness

• Abundant in its native range
• Benefits from human association (i.e. it is a human commensal)
• Capable of securing and ingesting a wide range of food
• Highly adaptable to different environments
• Highly mobile locally
• Is a habitat generalist

Uses

Environmental Services

Minor level of insect control.

Uses List

General

• Botanical garden/zoo
• Laboratory use
• Pet/aquarium trade
• Research model

Detection and Inspection

A. extremus is likely to be first noticed as an unusual anole unlike existing species in an area. Most areas suitable for A. extremus introduction will already have native or other introduced Anolis species. Schwartz and Henderson (1991) remains the most useful initial guide to identification, but identification should be confirmed by a taxonomic specialist, as there are hundreds of Anolis species potentially involved in introductions.

Similarities to Other Species/Conditions

There are approximately 400 species of anoles (Nicholson et al., 2012), so confirmation of new invasions of A. extremus or other similar species requires a taxonomic specialist. Schwartz and Henderson (1991) remains the most useful guide for initial recognition of introduced anoles.

Prevention and Control

Control

The great kiskadee (tyrant flycatcher, Pitangus sulphuratus) was introduced from Trinidad to Bermuda in 1957 to control introduced anoles, particularly A. grahami. It has been ineffective in controlling A. extremus or other anoles, but is implicated in the extinction of the endemic cicada and is becoming a major threat to native birds (Glasspool et al., 2007). Similarly, the introduced mongoose (Herpestes javanicus) preys on A. extremus in St Lucia, but apparently not enough to have a significant impact on their numbers (Daltry, 2009).

Daltry (2009) regarded island-wide eradication of A. extremus from St. Lucia to be neither necessary nor feasible, but suggested that removal by hand could be effective on a local scale. Her suggestions for management of the species were:

a) Listing as Unprotected under the Wildlife Protection Act.

b) Monitor the distribution and be vigilant for it invading the forest.

c) Support reptile conservation in other countries by prohibiting, screening and removing anole lizards from exported cargo.

Gaps in Knowledge/Research Needs

Most work on introduced populations of A. extremus has focused on basic biological questions rather than invasiveness or consequences. This state is likely to continue as economic impacts of Anolis introductions are minor or negligible.

References

Allen CR, Nemec KT, Wardwell DA, Hoffman JD, Brust M, Decker KL, Fogell D, Hogue J, Lotz A, Miller T, Pummill M, Ramirez-Yañez LE, Uden DR, 2013. Predictors of regional establishment success and spread of introduced non-indigenous vertebrates. Global Ecology and Biogeography, 22(7):889-899. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2486

Andrews R, Rand AS, 1974. Reproductive effort in anoline lizards. Ecology, 55:1317-1327.

Bacon JP, Gray JA, Kitson L, 2006. Status and conservation of the reptiles and amphibians of the Bermuda islands. Applied Herpetology, 3:323-344.

Bartlett RD, Bartlett PB, 1998. A field guide to Florida reptiles and amphibians. Houston, Texas, USA: Gulf Publishing, 282 pp.

Boos HEA, 1967. Reptiles on Huevos. Trinidad Field Naturalists' Club Journal, 1967:15-18.

Boos HEA, 1978. Survival of Anolis extremus on Huevos Island. Living World, 1977-1978:46-47.

Boos HEA, 1996. Some recent reptilian introductions to Trinidad. Living World, 1995-1996. 17-19.

Bursey CR, Goldberg SR, Telford SR Jr, Vitt LJ, 2012. Metazoan endoparasites of 13 species of Central American anoles (Sauria: Polychrotidae: Anolis) with a review of the helminth communities of Caribbean, Mexican, North American, and South American anoles. Comparative Parasitology, 79(1):75-132. http://www.bioone.org/doi/abs/10.1654/4530.1

Charles SP, Smith S, 2008. Observations of reptiles on Huevos Island, Trinidad, with five lizard species newly recorded for the island. Living World, 2008:28-32.

Corke D, 1992. The status and conservation needs of the terrestrial herpetofauna of the Windward Islands (West Indies). Biological Conservation, 62:47-58.

Daltry JC, 2009. The Status and Management of Saint Lucia's Forest Reptiles and Amphibians. SFA 2003/SLU/BIT-04/0711/EMF/LC., Finland: FCG Fauna & Flora, 80 pp. http://www.bananatrustslu.com/index.php?link=doccentre&project=sfa2003

Fields A, Horrocks JA, 2009. An annotated checklist of the herpetofauna of Barbados. Journal of the Barbados Museum and Historical Society, 55:263-283.

Fields A, Horrocks JA, 2011. Conservation of Caribbean island herpetofaunas, volume 2: Regional accounts of the West Indies [ed. by Hailey, A. \Wilson, B. S. \Horrocks, J. A.]. Leiden, Netherlands: Brill, 89-104.

Florida Fish and Wildlife Conservation Commission, 2013. Barbados anole. Species profiles - nonnatives. Florida, USA: Florida Fish and Wildlife Conservation Commission. http://myfwc.com/wildlifehabitats/nonnatives/reptiles/barbados-anole/

Garman S, 1887. On West Indian reptiles. Iguanidae. Bulletin of the Essex Institute, 19:25-50.

Giannasi N, Thorpe RS, Malhotra A, 1997. Introductions of Anolis species to the island of St. Lucia, West Indies: testing for hybrids using multivariate morphometrics. Journal of Herpetology, 31:586-589.

Glasspool AF, Sterrer W, Ward JA, 2007. Invasive alien species in Bermuda - the current situation. In: Biodiversity that matters: a conference on conservation in UK Overseas Territories and other small island communities, 6-12 October 2006 [ed. by Pienkowski]. London, UK: UK Overseas Territories Conservation Forum, 238-242. http://www.ukotcf.org

Goldberg SR, Bursey CR, Cheam H, 1997. Gastrointestinal helminths of 12 species of Anolis lizards (Polychrotidae) from the Lesser Antilles, West Indies. Journal of the Helminthological Society of Washington, 64:248-257.

Goldberg SR, Bursey CR, Tawil R, 1995. Gastrointestinal helminths of three introduced anoles: Anolis bimaculatus leachi, Anolis grahami, and Anolis roquet (Polychridae) from Bermuda. Journal of the Helminthological Society of Washington, 62(1):62-64.

Gorman GC, 1976. Observations on the distribution of Anolis extremus (Sauria: Iguanidae) on St Lucia, West Indies - a 'colonizing' species. Herpetologica, 32:184-188.

Gorman GC, Kim YJ, Yang SY, 1978. The genetics of colonization: loss of variability among introduced populations of Anolis lizards (Reptilia, Lacertilia, Iguanidae). Journal of Herpetology, 12:47-51.

Grant C, 1959. Herpetology of Barbados, B.W.I. Herpetologica, 15:97-101.

Hailey A, Quesnel VC, Boos HEA, 2009. The persistence of Anolis trinitatis as a naturalized lizard in Trinidad against hybridization pressure with Anolis aeneus. Applied Herpetology, 6:275-294.

Kraus F, 2009. Invading nature: Springer series in invasion ecology 4. Springer, 563 pp.

Krauss U, 2012. 161 Invasive Alien Species present in Saint Lucia and their current status. Caribbean Alien Invasive Species Network (CIASNET), 12 pp. http://www.ciasnet.org/wp-content/uploads/2010/08/IAS-present-in-SLU-May-2012-revision.pdf

Krysko KL, Burgess JP, Rochford MR, Gillette CR, Cueva D, Enge KM, Somma LA, Stabile JL, Smith DC, Wasilewski JA, Kieckhefer GNIII, Granatosky MC, Nielsen SV, 2011. Verified non-indigenous amphibians and reptiles in Florida from 1863 through 2010: outlining the invasion process and identifying invasion pathways and stages. Zootaxa, 3028:1-64.

Lazell JD, 1972. The anoles (Sauria, Iguanidae) of the Lesser Antilles. Bulletin of the Museum of Comparative Zoology, 143:1-115.

Lever C, 2003. Naturalized reptiles and amphibians of the world. Oxford, UK: Oxford University Press, 318 pp.

Losos JB, 1996. Dynamics of range expansion by three introduced species of Anolis lizards in Bermuda. Journal of Herpetology, 30:204-210.

Losos JB, 2009. Lizards in an evolutionary tree. Berkeley, California, USA: University of California Press, 512 pp.

Macedonia JM, Clark DL, 2003. Headbob display structure in the naturalized Anolis lizards of Bermuda: sex, context, and population effects. Journal of Herpetology, 37:266-276.

Meshaka WE Jr, Butterfield BP, Hauge JB, 2004. The exotic amphibians and reptiles of Florida [ed. by Meshaka, W. E.\Butterfield, B. P.\Hauge, J. B.]. Malabar, USA: Krieger Publishing Company, x + 155 pp.

Murphy JC, 1997. Amphibians and reptiles of Trinidad and Tobago. Malabar, Florida, USA: Krieger, 245 pp.

Nicholson KE, Crother BI, Guyer C, Savage JM, 2012. It is time for a new classification of anoles (Squamata: dactyloidae)? Zootaxa, 3477:1-108.

Nummelin M, 1992. Seasonal occurrence of juvenile Anolis extremus Garman in forest patches in Barbados. Journal of the Barbados Museum and Historical Society, 43:24-31.

Peters JA, Donoso-Barros R, 1970. Catalogue of the Neotropical Squamata. Part II: lizards and amphisbaenians. United States National Museum Bulletin, 297:1-293.

Poe S, 2013. 1986 Redux: new genera of anoles (Squamata: Dactyloidae) are unwarranted. Zootaxa, 3626:295-299.

Poulin R, Mouillot D, George-Nascimento M, 2003. The relationship between species richness and productivity in metazoan parasite communities. Oecologia, 137(2):277-285.

Powell R, Henderson RW, Farmer MC, Breuil M, Echternacht AC, Buurt Gvan , Romagosa CM, Perry G, 2011. Introduced amphibians and reptiles in the greater Caribbean: patterns and conservation implications. In: Conservation of Caribbean island herpetofaunas, volume 1: Conservation biology and the wider Caribbean [ed. by Hailey, A. \Wilson, B. S. \Horrocks, J. A.]. Leiden, Netherlands: Brill, 63-143.

Rivas GA, Molina CR, Ugueto GN, Barros TR, Barrio-Amorós CL, Kok PJR, 2012. Reptiles of Venezuela: an updated and commented checklist. Zootaxa, 3211:1-64. http://www.mapress.com/zootaxa/2012/f/z03211p064f.pdf

Roughgarden J, 1992. Comments on the paper by Losos: character displacement versus taxon loop. Copeia, 1992:288-295.

Schall JJ, Staats CM, 1997. Parasites and the evolution of extravagant male characters: Anolis lizards on Caribbean islands as a test of the Hamilton-Zuk hypothesis. Oecologia, 111:543-548.

Schoener TW, 1970. Nonsynchronous spatial overlap of lizards in patchy habitats. Ecology, 51:408-418.

Schwartz A, Henderson RW, 1991. Amphibians and reptiles of the West Indies. Gainesville, Florida, USA: University of Florida Press, 720 pp.

Staats CM, Schall JJ, 1996. Malarial parasites (Plasmodium) of Anolis lizards: biogeography in the Lesser Antilles. Biotropica, 28(3):388-393.

Thorpe RS, Leadbeater DL, Pook E, 2005. Molecular clocks and geological dates: cytochrome b of Anolis extremus substantially contradicts dating of Barbados emergence. Molecular Ecology, 14:2087-2096.

Wingate DB, 1965. Terrestrial herpetofauna of Bermuda. Herpetologica, 21:202-218.

Yang SY, Soule M, Gorman GC, 1974. Anolis lizards of the Eastern Caribbean: a case study in evolution. Genetic relationships, phylogeny, and colonization sequence of the roquet group. Systematic Zoology, 23:387-399.

Links to Websites

Contributors

07/05/13 Original text by:

A Hailey, The University of The West Indies, Trinidad and Tobago

Distribution Maps

• = Present, no further details
• = Evidence of pathogen
• = Widespread
• = Last reported
• = Localised
• = Presence unconfirmed
• = Confined and subject to quarantine
• = See regional map for distribution within the country
• = Occasional or few reports

Download KML file Download CSV file

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Please click OK to ACCEPT or Cancel to REJECT

OK Cancel

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Please click OK to ACCEPT or Cancel to REJECT

OK Cancel