Anolis

Displaying Carolina anole Anolis carolinensis, copyright Jefferson Heard.

Belongs within: Iguania.

Anolis, the anoles, is a diverse genus of more or less elongate lizards found in warmer parts of the Americas. Members of the genus possess a distinct dewlap under the throat that may be inflated for display. There has been much debate in recent years whether this genus should be defined as including the entire diversity of anoles, or whether it should be restricted to a smaller group centred around the type species A. carolinensis.

Anole, anole, anole, anole
Published 7 May 2012
Brown anole Anolis sagrei, a species that has become widely distributed in the Caribbean and also in Florida, photographed by Ianaré Sévi.

Today, the watchword is Anolis. Anolis, the anoles, is an enormous assemblage of lizards found in warmer parts of the Americas: with well over 350 species, it is the largest genus generally recognised among the amniotes. Species within the genus have received a lot of attention for their ecological diversity. In some parts of Cuba, there may be fourteen or fifteen Anolis species found in a single locality, each occupying their own distinct niche (Thomas et al. 2009). Examples of anole ecotypes include crown-giants, up to and above half a metre in length, that live in the forest canopy; slender, short-legged twig anoles, that creep along narrow branches; and also slender, but much longer-legged, grass-bush anoles that are found in dense undergrowth (Losos 2009).

The Gorgona Island anole Anolis gorgonae, photographed by Luke Mahler.

Some species of anole have even been the subjects of direct experimental studies on evolutionary processes. Hind limb length in different anole species has been observed to correlate with substrate usage: those species that prefer wider branches have longer hind legs than those utilising smaller branches. In order to test whether natural selection played a direct part in determing leg length, the brown anole Anolis sagrei was introduced in 1977 and 1981 to fourteen small islands, of varying vegetation type, in the Bahamas that had been previously uninhabited by anoles. After ten years had passed, measurements were taken of anoles on each of the islands where they had persisted and compared back to the source population. It was demonstrated that (a) many of the experimental populations were statistically significantly different from the source population after ten years, and (b) the degree of difference between populations was correlated with the degree of difference in the vegetation oof the two localities (Losos et al. 1997). However, later studies of brown anoles in the laboratory reared in cages with different-sized available substrates indicates that leg length in anoles is, to some extent, phenotypically plastic depending on environmental pressures (Losos et al. 2000). Nevertheless, a selective component to variation was supported by experiments involving translocation between montane and lowland habitats of the Dominican anole Anolis oculatus (Thorpe et al. 2005).

The Hispaniolan hopping anole Anolis barbouri, a species long included in a separate genus Chamaelinorops, photographed by Rob Op ‘t Veld.

Being such a huge genus, it is not surprising that attempts have been made to break Anolis down to more manageable units, with varying success. Hillis (1996, as quoted in Poe 2004) described anoles as “a huge group where all the species look virtually the same”: a quite unfair aspersion (see above) but nevertheless expressive of the difficulties in establishing relationships between species (ecological convergence, for instance, is rampant). Anoles have been divided into two major subgroups, the Alpha and Beta anoles, on the basis of the presence (Beta) or (Absence) of transverse processes on the caudal vertebrae, and some authors have proposed recognising the Beta anoles as a separate genus Norops. Recent phylogenetic analyses have agreed that the Beta anoles are monophyletic, but nested deeply in the Alpha anoles (Poe 2004; Nicholson et al. 2005). Because of difficulties in defining usual subgroups among the Alpha anoles, recent authors have therefore continued to maintain a super-sized Anolis*.

*Which just highlights again how the binomial system can force false dichotomies. The nested position of ‘Norops‘ within ‘Anolis‘ means that one must either (a) subdivide Anolis, perhaps impractically, (b) sink Norops and obscure that group’s distinctiveness, or (c) recognise a paraphyletic Anolis, obscuring the closer relationships between some Anolis and Norops species. Three suboptimal choices, but you must pick one because you can’t have species without genera. Surely it would be better overall if one could just sidestep the question by recognising a clade Norops within a clade Anolis?

The Cuban false chamaeleon Anolis chamaeleonides, another species previously in a separate genus (Chamaeleolis), photographed by Lubomir Hlasek.

Also of interest are the biogeographic patterns within Anolis that phylogenetic analysis has revealed. Both the Alpha and Beta anoles have species on the Caribbean islands as well as continental South America (a little less than half the currently recognised Anolis species are found on Caribbean islands). The South American Alpha anoles form a clade (sometimes recognised as a separate genus Dactyloa) that, together with the Anolis roquet group of species found in the southern Lesser Antilles, forms the sister group of most or all of the remaining Anolis species (Poe 2004; Nicholson et al. 2005). Most lineages within the remaining anoles are Caribbean; the South American Beta anoles also form a single clade whose nested position among Caribbean taxa indicates a relatively rare demonstrable case of dispersal from an island to a continent (as opposed to the other way around, the more usual expectation in biogeography). Most of the Greater Antillean islands are home to multiple lineages of anoles; the exception is Jamaica which, except for the recently arrived Anolis sagrei, is inhabited by a single clade of Beta anoles (the sister group to the South American Beta anoles). The Carolina anole Anolis carolinensis of the southeast United States is also of Caribbean origin, being nested among a clade of Cuban species. It is worth noting that this last continental colonisation is, in a way, currently repeating itself: though probably brought by human agents, a number of Caribbean anole species are now known in the wild from Florida.

Systematics of Anolis
<==Anolis Daudin 1802GS86 (see below for synonymy)
    |--+--+--A. punctatus Daudin 1802SVL03, GS86 [=*Dactyloa punctataGS86]
    |  |  |    |--A. p. punctatusDS86
    |  |  |    `--A. p. boulengeriDS86
    |  |  |--A. aequatorialis [=Dactyloa aequatorialis]GS92
    |  |  |--A. latifrons [=Dactyloa latifrons]GS92
    |  |  `--A. tigrinum [=Dactyloa tigrina]GS92
    |  `--+--+--A. luciaeYSG74
    |     |  `--+--A. blanquillanusYSG74
    |     |     `--A. bonairensisYSG74
    |     `--+--A. richardiYSG74
    |        `--+--A. griseusYSG74
    |           `--+--A. trinitatisYSG74
    |              `--+--A. aeneusYSG74
    |                 `--+--A. extremusYSG74
    |                    `--A. roquet [=Dactyloa roquet; incl. A. alligator, *Phalangoptyon alligator]GS92
    |                         |--A. r. roquetGK75
    |                         |--A. r. majolgrisGK75
    |                         `--A. r. summusGK75
    `--+--XiphosurusGS92 [=Semiurus Fitzinger 1843GS92, GS86]
       |    |--‘Anolis’ barahonaeGBW80
       |    |--X. cuvieri (Merrem 1820)GS92, GS86 [=Anolis cuvieriGS92, *Semiurus cuvieriGS86]
       |    |--X. ricordi [=Anolis ricordi]GS92
       |    `--‘Anolis’ rooseveltiGBW80
       `--+--+--A. armouri [=*Audantia armouri, Ctenonotus armouri]GS92
          |  |--A. cybotesSVL03 [=Ctenonotus cybotesGS92]
          |  `--A. shrevei [=Ctenonotus shrevei]GS92
          `--+--A. paternusSVL03
             `--+--+--A. cookiGBW80
                |  |--A. cristatellusSVL03 [=Ctenonotus cristatellusGS92]
                |  |--A. distichus [=Ctenonotus distichus]GS92
                |  |--A. evermanni [=Ctenonotus evermanni]GS92
                |  |--A. gundlachi [=Ctenonotus gundlachi]GS92
                |  |--A. krugi [=Ctenonotus krugi]GS92
                |  |--A. monensisGBW80
                |  |--A. poncensisGBW80
                |  |--A. pulchellusGBW80
                |  `--A. scriptusGBW80
                `--+--+--+--A. chlorocyanusGS92
                   |  |  |--A. coelestinusGS92
                   |  |  `--A. darlingtoniGS92
                   |  |--+--A. hendersoniGS92
                   |  |  `--+--A. bahorucoensisGS92
                   |  |     `--A. etheridgeiGS92
                   |  `--+--A. angusticepsGS92
                   |     `--+--A. alutaceusGS92
                   |        |--A. luciusGS92
                   |        `--A. monticolaGS92
                   `--+--A. olssoniGS92
                      |--A. semilineatusGS92
                      `--+--*A. carolinensis Voigt 1832GS86, GS92, GS86
                         `--+--+--A. sagreiSVL03 [=Norops sagreiGS92]
                            |  `--+--A. homolechis [=Norops homolechis]GS92
                            |     `--A. ophiolepis [=Norops ophiolepis]GS92
                            |--+--A. fuscoauratusGS92 [incl. A. bocourtiDS86]
                            |  |--+--A. auratus Daudin 1802GS92, KS08 [=*Norops auratusGS86]
                            |  |  `--A. oncaGS92
                            |  `--+--A. meridionalisGS92
                            |     `--A. petersiGS92
                            `--+--A. garmani [=Norops garmani]GS92
                               |--A. grahami [=Norops grahami]GS92
                               |--A. lineatopus [=Norops lineatopus]GS92
                               |--A. opalinus [=Norops opalinus]GS92
                               `--A. valencienni [=Norops valencienni]GS92
Anolis incertae sedis:
  A. allogusGH01
  A. altitudinalis Garrido 1985 [=A. isolepis altitudinalis]GH01
  A. argenteolusGH01
  A. argillaceousGH01
  ‘Norops’ biporcatusGS92
  A. bombicepsDS86
  A. centralisGH01
  A. chamaeleonidesGH01
  A. chrysolepisDS86
    |--A. c. chrysolepisDS86
    `--A. c. scypheusDS86
  A. dominicanusP92
  A. dunniDD61
  A. electrum Lazell 1965P92
  A. equestris [=*Eupristis equestris]GS92
  ‘Dactyloa’ frenataGS92
  A. fungosus Myers 1971KS08
  A. gadoviDD61
  A. guazumaGH01
  A. heteropholidotus Mertens 1952SVK08
  A. incredulus Garrido & Moreno 1998GH01
  A. insolitusC96
  A. isolepisGH01
  A. limifronsP92
  A. liogasterDD61
  A. loysianusGH01
  A. megapholidotusDD61
  A. microlepidotusDD61
  A. microtus Cope 1871KS08
  A. muralla (Köhler, McCranie & Wilson 1999)SVK08
  A. nebuloidesDD61
  A. nebulosusDD61
  A. nobleiGH01
  A. occultusGS92
  A. omiltemanusDD61
  A. oporinus Garrido & Hedges 2001GH01
  A. ortoni Cope 1868 [incl. A. bouvierii Bocourt 1873]K07
  A. polylepis Peters 1873KS08
  A. porcatusGH01
  A. porcusGH01
  A. principalisF15
  A. rejectusGH01
  A. salvini Boulenger 1885 [incl. A. vociferans Myers 1971]K07
  A. smallwoodiGH01
  A. sminthus Dunn & Emlen 1932SVK08
  A. subocularisDD61
  A. trachydermaDS86
  A. transversalisDS86
  A. vanidicusGH01
  A. wermuthi (Köhler & Obermeier 1998) [=Norops wermuthi]SVK08
  0--A. stratulusGBW80
  `--+--+--A. acutusGK76
     |  `--+--A. pogus [=A. wattsi pogus]GK76
     |     `--+--A. schwartzi [=A. wattsi schwartzi]GK76
     |        `--A. wattsiGK76
     `--+--A. bimaculatus Sparmann 1784GS92, GS86 [=*Ctenonotus bimaculatusGS86]
        `--+--+--A. gingivinusGK76
           |  `--+--A. nubilusGK76
           |     `--A. sabanusGK76
           `--+--A. leachi [=A. bimaculatus leachi]GK76
              `--+--A. oculatusGK76
                 |    |--A. o. oculatusGK76
                 |    `--A. o. winstoniGK76
                 `--+--A. ferreus [=A. marmoratus ferreus]GK76
                    `--+--A. lividusGK76
                       `--A. marmoratusGK76

Anolis Daudin 1802GS86 [incl. Audantia Cochran 1934GS92, Ctenonotus Fitzinger 1843GS86, Dactyloa Wagler 1830GS86, Eupristis Fitzinger 1843GS92, Norops Wagler 1830GS86, Phalangoptyon Wagler 1833GS92]

*Type species of generic name indicated

References

[C96] Campbell, N. A. 1996. Biology 4th ed. The Benjamin/Cummings Publishing Company, Inc.: Menlo Park (California).

[DD61] Davis, W. B., & J. R. Dixon. 1961. Reptiles (exclusive of snakes) of the Chilpancingo Region, Mexico. Proceedings of the Biological Society of Washington 74: 37–56.

[DS86] Dixon, J. R., & P. Soini. 1986. The Reptiles of the Upper Amazon Basin, Iquitos Region, Peru. Milwaukee Public Museum: Milwaukee.

[F15] Fowler, H. W. 1915. Cold-blooded vertebrates from Florida, the West Indies, Costa Rica, and eastern Brazil. Proceedings of the Academy of Natural Sciences of Philadelphia 67 (2): 244–269.

[GH01] Garrido, O. H., & S. B. Hedges. 2001. A new anole from the northern slope of the Sierra Maestra in eastern Cuba (Squamata: Iguanidae). Journal of Herpetology 35 (3): 378–383.

[GBW80] Gorman, G. C., D. G. Buth & J. F. Wyles. 1980. Anolis lizards of the eastern Caribbean: a case study in evolution. III. A cladistic analysis of albumin immunological data, and the definition of species groups. Systematic Zoology 29 (2): 143–158.

[GK75] Gorman, G. C., & Y. J. Kim. 1975. Genetic variation and genetic distance among populations of Anolis lizards on two Lesser Antillean island banks. Systematic Zoology 24 (3): 369–373.

[GK76] Gorman, G. C. & Y. J. Kim. 1976. Anolis lizards of the eastern Caribbean: a case study in evolution. II. Genetic relationships and genetic variation of the bimaculatus group. Systematic Zoology 25 (1): 62–77.

[GS86] Guyer, C., & J. M. Savage. 1986. Cladistic relationships among anoles (Sauria: Iguanidae). Systematic Zoology 35 (4): 509–531.

[GS92] Guyer, C., & J. M. Savage. 1992. Anole systematics revisited. Systematic Biology 41 (1): 89–110.

[K07] Köhler, G. 2007. Assessing the status of Anolis salvini Boulenger 1885 and A. bouvierii Bocourt 1873 based on the primary types (Reptilia, Squamata, Polychrotidae). Senckenbergiana Biologica 87 (1): 125–130.

[KS08] Köhler, G., J. Sunyer, M. Ponce & A. Batista. 2008. Noteworthy records of amphibians and reptiles in Panama (Amphibia: Plethodontidae, Craugastoridae, Hylidae; Reptilia: Polychrotidae). Senckenbergiana Biologica 88 (2): 329–333.

Losos, J. B. 2009. Lizards in an Evolutionary Tree: Ecology and adaptive radiation of anoles. University of California Press.

Losos, J. B., D. A. Creer, D. Glossip, R. Goellner, A. Hampton, G. Roberts, N. Haskell, P. Taylor & J. Ettling. 2000. Evolutionary implications of phenotypic plasticity in the hindlimb of the lizard Anolis sagrei. Evolution 54 (1): 301–305.

Losos, J. B., K. I. Warheit & T. W. Schoener. 1997. Adaptive differentiation following experimental island colonisation in Anolis lizards. Nature 387: 70–73.

Nicholson, K. E., R. E. Glor, J. J. Kolbe, A. Larson, S. B. Hedges & J. B. Losos. 2005. Mainland colonization by island lizards. Journal of Biogeography 32: 929–938.

Poe, S. 2004. Phylogeny of anoles. Herpetological Monographs 18: 37–89.

[P92] Poinar, G. O., Jr. 1992. Life in Amber. Stanford University Press: Stanford.

[SVL03] Schulte, J. A., II, J. P. Valladares & A. Larson. 2003. Phylogenetic relationships within Iguanidae inferred using molecular and morphological data and a phylogenetic taxonomy of iguanian lizards. Herpetologia 59 (3): 399–419.

[SVK08] Sunyer, J., M. Veselý & G. Köhler. 2008. Morphological variation in Anolis wermuthi (Köhler & Obermeier 1998), a species endemic to the highlands of north-central Nicaragua (Reptilia, Squamata, Polychrotidae). Senckenbergiana Biologica 88 (2): 335–343.

Thomas, G. H., S. Meiri & A. B. Phillimore. 2009. Body size diversification in Anolis: novel environment and island effects. Evolution 63 (8): 2017–2030.

Thorpe, R. S., J. T. Reardon & A. Malhotra. 2005. Common garden and natural selection experiments support ecotypic differentiation in the Dominican anole (Anolis oculatus). American Naturalist 165 (4): 495–504.

[YSG74] Yang, S. Y., M. Soulé & G. C. Gorman. 1974. Anolis lizards of the eastern Caribbean: a case study in evolution. I. Genetic relationships, phylogeny, and colonization sequence of the roquet group. Systematic Zoology 23 (3): 387–399.

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