Examples of the six ecomorphs proposed by Williams.
Left column, top to bottom:
A. luteogularis (crown giant)
A. homolechis (trunk ground)
A. heterodermus (twig)
Right column, top to bottom:
A. porcatus (trunk crown)
A. distichus (trunk)
A. pulchellus (grass bush)

The ecomorph concept is a term first coined by Ernest Edward Williams in 1972 which he defined as a “species with the same structural habitat/niche, similar in morphology and behavior, but not necessarily close phyletically.”[1] Williams first applied this definition to the Greater Antillean anoles (especifically in Puerto Rico) upon observing their evolutionary radiation, although it has since been used widely elsewhere.[2]

Anoles have repeatedly evolved into similar forms on different islands, dubbed 'ecomorphs'. Convergence is in microhabitat specialty, behavior, and morphology.[3] Langerhans, Knouft & Losos call the set of Anolis lizard ecomorphs of the Greater Antilles "a classic example of convergent evolution."[4][5] Jonathan Losos defined six Anolis ecomorphs according to the predominant microhabitat (e.g. grasses, open ground, different parts of trees) of the respective anolis: crown-giant, grass-bush, trunk, trunk-crown, trunk-ground, and twig.[5][6]

Contents

Crown Giant ecomorphEdit

These are anoles which inhabit the uppermost canopy of trees, they all share certain morphological characteristics such as relatively large body size, large heads, large sub-digital lamellae and serrated dorsal crest,most species are predominantly green. Crown giant anoles can be informally subdivided into long legged species (which move by jumping from tree to tree) and short legged species (which do not often jump and mostly crawl from one area to another.) Because of their large size these anoles can take a wide range of prey items from smaller lizards to small birds,all species are also known to consume fruit. Though they all share a similar body plan crown giant anoles vary significantly in size from one island to the other. A few examples of crown giant anoles are shown below.

Species Image Distribution
Anolis baracoae
 
Baracoa giant anole
Baracoa,Cuba
Anolis ricordii
 
Ricord's giant anole
Hispaniola
Anolis cuvieri Puerto Rico
Anolis garmani Jamaica,introduced to Florida and the Cayman Islands
 
The hind legs of Anolis cuvieri, a long-legged crown giant anole

Trunk-crown ecomorphEdit

These are anoles which inhabit the uppermost reaches of the trunks of tall trees as well as the lower canopy; they are generally found several metres off the ground. Trunk-crown anole are usually predominantly green and have relatively large sub-digital toe-pads and short stout legs to aid in arboreal locomotion. These anoles eat small arboreal insects, smaller lizards, and some species have been observed to consume fruits and nectar; they have triangular, flattened heads, possibly to aid in nectar consumption.Trunk-crown anoles often exhibit the most drastic color changing abilities of any species and are capable of entering several darker phases which are used selectively from very dark to convey stress to light brown or grey for thermoregulation. Other anole ecomorphs are able to change color, but with the exception of some crown giants this is usually to a lesser extent. A few examples of trunk-crown anoles are shown below.

Species Image Distribution
Anolis allisoni Cuba
Anolis coelestinus
 
Haitian white-lipped anole
Hispaniola
Anolis evermanni
 
Emerald anole
Puerto rico
Anolis grahami Jamaica,introduced to Bermuda
 
Anolis allisoni showing one of its thermoregulatory darker phases.

Trunk ecomorphEdit

Trunk anoles are found only on Cuba and Hispaniola in the Greater Antilles however the Hispaniolan species A.distichus is also native to the Bahamas and has introduced populations in Florida.Trunk anoles are mid-sized anoles with short limbs and tails and small,short triangular heads.As their name suggest trunk anoles are found mainly on the trunks of tall trees and their diet consists primarily of ants.

Species Image Distribution
Anolis distichus distichus Hispaniola,introduced to Florida
Anolis distichus ignigularis

 

Hispaniola

Trunk-ground ecomorphEdit

Trunk-ground anoles characterized by their tendency to perch on the lower trunk of trees or on rocks immediately under the tree trunk,they typically perch with their head facing downwards to locate any insects located on the ground, after spotting food they jump down to capture it and retreat back up into the tree. These anoles will also eat smaller lizards or juveniles of their own species when the opportunity presents itself. Trunk-ground anoles are stocky and usually have relatively large heads and long legs to facilitate jumping. Anoles of this ecomorph are predominantly brown in color but can change to lighter or darker shades of brown based on their mood or body temperature.

Name Image Distribution
Anolis sagrei Cuba, Little Cayman and the Bahamas, Introduced to Florida, Texas, Costa Rica, Hawaii, Jamaica, Singapore, St. Maarten, Barbados,Grenada and the Grenadines, Aruba and Taiwan.
Anolis cybotes The Hispaniolan island bank,introduced to Florida and Suriname
Anolis cristatellus Puerto Rican island bank,introduced to Florida,Dominica, the Dominican Republic and St.Martin
Anolis lineatopus Jamaica

ReferencesEdit

  1. ^ Williams, Ernest E. (1972). "3. The Origin of Faunas. Evolution of Lizard. Congeners in a Complex. Island Fauna: A Trial Analysis". In T. Dobzhansky et al. Evolutionary Biology. Meredith Corporation. pp. 47–89.CS1 maint: Uses editors parameter (link) refer page 72
  2. ^ Research Summary. Archived March 29, 2015, at the Wayback Machine Losos Laboratory. Harvard University. January 2013. Retrieved 10 September 2013.
  3. ^ 2009 Anolis symposium. Ernest Williams. Harvard University. Department of Organismic and Evolutionary Biology. 2009. Retrieved 10 September 2013.
  4. ^ Langerhans, Knouft & Losos (2006) Evolution, vol. 6, p.362.
  5. ^ a b Topic: Anolis lizard ecomorphs. Map of Life: Convergent Evolution Online. Retrieved 10 September 2013.
  6. ^ "Anolis lizard ecomorphs." Map of Life. 10 September 2013. 10 September 2013.

See alsoEdit