Anolis evermanni
| Anolis evermanni | |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Iguania |
| Family: | Dactyloidae |
| Genus: | Anolis |
| Species: | A. evermanni
|
| Binomial name | |
| Anolis evermanni Stejneger, 1904
| |
Anolis evermanni, the emerald anole, Evermann's anole, or small green anole, is a species of lizard included within the family Dactyloidae.[2][3] Anolis evermanni are native to and most commonly found in Puerto Rico, mainly in wet forests. Anolis evermanni are medium-sized lizards and bright emerald-green in color.[2][3] Anolis evermanni are studied for their behavior as well as the evolution of the Dactyloidae family which are known as anoles, a group of lizards.[4][5] Anoles are found throughout the Americas and are related to iguanas.[6]
Description
Anolis evermanni are medium-sized and a bright emerald-green color, but can also progress to a dark brown color when aroused. Males are typically larger than females with males having a snout-to-vent length of 7 cm (2.75 in) and females having a snout-to-vent length of 4.5 cm (1.75 in). They have a flattened body and head, slightly compressed tail, pointy snout, short legs, and large toe-pads. Males and females both have a yellow dewlap, a flap of skin hanging below the neck. Male dewlaps are generally larger than female dewlaps.[2][3]
Distribution and Habitat
Anolis evermanni are native to and found in Puerto Rico. Specifically, they can be found in wet forests including the El Yunque rainforest, the Luquillo mountains and forest, and the Cordillera Central mountain range.[2][3]
In these areas, Anolis evermanni are typically found around trees, on rocks, or bamboo groves. They mainly use the upper portions, 2 m above the ground, of trees as perching sites and to search for food. Their short legs and large toe-pads allow them to move more easily in the upper portions of trees, particularly on small branches.[2][3][4]
Conservation
The International Union for Conservation of Nature lists Anolis evermanni as a least-concern species as the species remains common in Puerto Rico and its habitat has no widespread threats. Current threats include residential and commercial development as Anolis evermanni are not found in deforested areas. Additionally, climate change is a threat to forest habitats in which Anolis evermanni are found.[1]
No species-specific conservation efforts are taking place for Anolis evermanni. However, they are most often found in protected areas which conserve their natural habitats.[1]
History and Taxonomy
Anolis evermanni is a species of lizard named after Dr. Barton Warren Evermann, an American ichthyologist.[3]
Anolis evermanni are in the Anolis genus of anoles, which includes over 400 species of lizards native to the Americas. Anoles typically share similar sizes and shapes but differ in the habitats they occupy. This is an example of adaptive radiation as lizards on different islands adapt to different habitats. The Anolis genus is part of the larger Dactyloidae family of anoles. This is an example of convergent evolution where lizards on different islands with similar habitats may evolve to share similar morphologies.[6]
Among the Anolis genus, Anolis evermanni are classified in the trunk-crown ecomorph, generally living in the upper trunks and canopies of trees. Other trunk-crown anoles include Anolis allisoni, Anolis coelestinus, and Anolis grahami.[6]
Anolis carolinensis is another related lizard species which is also able to change colors between shades of green and brown.[6]
Genome
From 65 to 125 million years ago, anoles experienced radiation into the different species found today. Anoles vary greatly in their karyotypes with Anolis evermanni having a diploid number of 26 while other anoles having a diploid number as large as 44. They also vary in their sex chromosomes with some species having simple XX/XY sex chromosomes and others having many sex chromosomes.[5]
Diet
Similar to other trunk-crown Anolis ecomorphs, Anolis evermanni eat small insects. Anolis evermanni have also been found to eat the nectar of Mecranium latifolium flowers in Puerto Rico forests; this is a recent finding, but other anoles have also been found to lick nectar from flowers. Some anoles may be pollinators of certain flowers. When foraging, similar to other anoles, Anolis evermanni are typically sit-and-wait foragers meaning they have long periods of inactivity followed by short bursts of activity to capture prey.[6][7][8]
Reproduction and Life Cycle
Reproduction
Anolis evermanni females display seasonal changes in egg production. From April to September, most Anolis evermanni individuals are reproductive and many females have two oviducal eggs. Almost no reproduction occurs between November and January.[9] Like other anoles, Anolis evermanni females lay eggs and hide them.[10]
Behavior
Anolis evermanni, in addition to other anoles, have been studied for their behavioral interactions and evolution.[4][5]
Territoriality
Anolis evermanni are a territorial species with both males and females using displays of their dewlaps, tails, and tongues to defend their territory from other lizards. When these displays fail, Anolis evermanni may also fight over territory.[2]
Competition with Anolis gundlachi
Anolis evermanni have been found to act with other lizard species including Anolis gundlachi. Both lizard species are native to Puerto Rico and they are of similar sizes. However, they are ecologically different as Anolis gundlachi typically occupying the lower portions of trees while Anolis evermanni occupy upper tree areas. Regradless, competition between the two lizard species still exists. In a study on the interactions between the two species, when Anolis gundlachi are removed from an environment, the number of Anolis evermanni was found to increase over time. This may be due to interspecific competition between the two lizard species. The two lizard species share similar prey of insects and have been found to contest territory. Similar to behavioral displays between Anolis evermanni lizards, with two different species, the lizards also use push-ups, their dewlaps and tongues to compete for territory and prey. In this case, Anolis gundlachi have been found to win encounters over Anolis evermanni counterparts. Intraguild predation is also possible among these lizards with male Anolis gundlachi adults potentially eating Anolis evermanni juveniles. Without the competition with Anolis gundlachi, Anolis evermanni were able to occupy areas, mainly lower tree trunks, that were previously defended by Anolis gundlachi.[4]
Other possible hypotheses regarding the ecological differences between Anolis evermanni and Anolis gundlachi include having common predators and parasites. But in this case, as the two lizard species are in close distance to each other, it is unlikely that these factors have a significant role.[4]
Biting
Anolis evermanni, as well as other anoles, do bite other animals and humans. However, most anole bites are harmless and anoles only bite as a protective measure when provoked.[11]
Coloration and Behavior
Anolis evermanni are typically bright emerald-green in color which does not blend in well with tree trunks but may blend in better with other vegetation. But, when aroused, Anolis evermanni will turn a dark brown color which may blend in better with tree trunks.[12]
Problem-Solving
Anolis evermanni have been studied to test their behavioral flexibility. Lizards are believed to have limited cognitive abilities. However, in a study with Anolis evermanni, the lizards were found to adjust their behavior in order to receive a reward. In this case, lizards learned to remove a disc in order to obtain food. This study demonstrated adaptation capabilities within the Anolis evermanni lizard. [13]
However, whether this behavior can accurately assess behavioral flexibility has been disputed. Other researchers contend that Anolis evermanni have demonstrated learning abilities but not necessarily a flexible learning ability.[14]
Enemies
Predators
Predators of Anolis evermanni include terrestrial predators like snakes. Anolis evermanni may also perceive humans as predators, and other animals like birds may be predators as well. As they are typically found on or near trees, when approached by a terrestrial predator, Anolis evermanni exhibit escape behavior by climbing around or up a tree. This behavior varies depending on the perch height of the Anolis evermanni individual. If a lizard is lower in a tree, the lizard exhibits escape behavior more quickly when approached by a predator than if the lizard were higher in the tree. At perch heights less than or exactly 2.0 m, Anolis evermanni individuals exhibit escape behavior, but at perch heights above 2.0 m, no escape behavior is exhibited.[12]
Physiology
Locomotion
Anolis evermanni locomotion depends on location, showcasing different movement on boulders and trees. Anolis evermanni exhibit jumping and walking behavior at similar levels on boulders and trees. However, running behavior is increased 238% on trees. Overall locomotion for Anolis evermanni is 46% higher on trees. Their short legs and large toe-pads aid locomotion on trees. Another possible explanation for increased running and movement on trees is that tree trunks provide a continuous area for Anolis evermanni to move on. Additionally, Anolis evermanni are heliophilic and may move toward areas with sunlight including the forest canopy and gaps in the canopy where sunlight can reach.[8]
Interactions with Humans
Anolis evermanni are often found on coffee plantations in Puerto Rico, especially in areas nearby forests. Anolis evermanni are being affected by human activity and forest conversion in their natural habitats as they do not continue to live in deforested areas. Anolis evermanni have not been found to have other significant interactions with humans and are not involved with major human uses or trade.[1]
References
- ^ a b c d Mahler, D.L. & Rodriguez, C. (2020). "Anolis evermanni ". The IUCN Red List of Threatened Species 2020: e.T74995322A75171581. https://www.iucnredlist.org/species/74995322/75171581. Downloaded on 29 March 2021.
- ^ a b c d e f "Emerald Anole". United States Department of Agriculture Forest Service. Retrieved 7 October 2021.
- ^ a b c d e f Uetz, Peter; Hallermann, Jakob. "Anolis evermanni STEJNEGER, 1904". The Reptile Database. Retrieved 7 October 2021.
- ^ a b c d e Leal, Manuel; Rodriguez-Robles, Javier; Losos, Jonathan (1998). "An experimental study of interspecific interactions between two Puerto Rican Anolis lizards" (PDF). Oecologia (117): 273–278. Retrieved 7 October 2021.
- ^ a b c Giovannotti, M (22 March 2016). "New insights into sex chromosome evolution in anole lizards (Reptilia, Dactyloidae)" (PDF). Chromosoma (126): 245–260. doi:10.1007/s00412-016-0585-6. Retrieved 7 October 2021.
- ^ a b c d e Uetz, P.; Hallermann, J. (2018). "Dactyloidae". The Reptile Database. Retrieved 7 October 2021.
- ^ Colón Archilla, Alfredo (Sep 2010). "Nectarivory in Puerto Rican Emerald Anoles (Anolis evermanni )" (PDF). IRCF Rept iles & Amph i bians •. 17 (3): 145. Retrieved 7 October 2021.
- ^ a b Losos, Jonathan (1990). "Concordant evolution of locomotor behavior, display rate and morphology in Anolis lizards" (PDF). Anim Behavior (39): 879–890. Retrieved 7 October 2021.
- ^ Gorman, George; Licht, Paul (March 1974). "Seasonality in Ovarian Cycles among Tropical Anolis Lizards". Ecology. 55 (2): 360–369. Retrieved 7 October 2021.
- ^ "Family Dactyloidae: Anoles". KingSnake. Retrieved 7 October 2021.
- ^ Revell, Liam. "Field Work in Puerto Rico and a First Lizard Bite". Anole Annals. Retrieved 7 October 2021.
- ^ a b Cooper, W.E. (24 March 2006). "Risk factors affecting escape behaviour by Puerto Rican Anolis lizards". Canadian Journal of Zoology. 84 (4). doi:10.1139/z06-018. Retrieved 7 October 2021.
- ^ Powell, Brian; Leal, Manuel (13 July 2011). "Behavioural flexibility and problem-solving in a tropical lizard". Animal behaviour. 8 (1): 28–30. doi:10.1098/rsbl.2011.0480. Retrieved 7 October 2021.
- ^ Vasconcelos, Marco; Monteiro, Tiago; Kacelnik, Alex (7 December 2011). "On the flexibility of lizards' cognition: a comment on Leal & Powell (2011)". Animal behaviour. 8 (1): 42–43. doi:10.1098/rsbl.2011.0848. Retrieved 7 October 2021.