Lizards are among the most diverse groups of reptiles, with more than 5,600 species. [1] With such diversity in physical and behavioral traits, lizards have evolved many ways to communicate. [2] Communication may be physical, chemical, tactile, or vocal, and varies according to habitat, sexual selection practices, and predator avoidance methods. Each type of communication uses different sensory systems, including visual, olfactory, and auditory. [3] [4] [5]
Lizards communicate with members of their own species [6] to find appropriate mates [7] and when competing for resources such as food or habitat. Intraspecific communication is instrumental in sexual selection, as phenotypic variation within a population can result in some individuals mating more than others.
Lizard species use interspecific communication in competition for resources and during predator-prey interactions. Anolis cristatellus , for example, uses "pushup displays" as a pursuit-deterrent signal to predators, communicating that the anole is healthy and would likely be able to escape if pursued. This encourages the predator to go after other prey (potentially anoles of the same species in worse condition). Lizards in better condition perform this behavior more frequently, making it a form of honest signaling. [8]
Lizards have evolved several modes of communication, including visual, chemical, tactile, and vocal. [9] [2] Chemical and visual communication are widespread, with visual communication being the most well-studied, while tactile and vocal communication have traditionally been thought to occur in just a handful of lizard species; however, modern scientific techniques have allowed for greater study of non-visual modes of communication, and they may be more widespread than previously thought.[ citation needed ]
Lizards that use visual communication gather information by observing other lizards' physical and behavioral characteristics, somewhat like humans communicating using body language. Lizards that use visual communication often have highly developed visual systems—most can see colors, and some can see UV light. [10] [11]
Lizards can have vibrant colors and patterns and flashy behaviors intended to communicate both inter- and intraspecifically. Vibrant colors and patterns can draw attention from predators or competition, so they may be located on a dewlap or an area of the body that is usually hidden, like the belly. Many Anolis species have dewlaps [12] that they can extend and retract at will, such as when attracting mates or dueling with competitors. [13] The dewlaps are often colorful but are well hidden when retracted. Some Sceloporus lizards develop vibrant blue and black coloration on their bellies during breeding season. [14] This color is not visible to other lizards unless the lizard flattens its body to expose the colorful parts of its belly, a behavior called dorsal ventral flattening. [15]
Visual communication is common among species that live at relatively high population densities and often come into close contact. Visual communication is well suited for use in many different habitats and can be modified by lizards to accommodate changing habitat conditions, [16] so long as individuals come into contact frequently enough.[ clarification needed ]
Some lizards deposit chemicals such as pheromones into the environment, [17] where the chemicals can elicit changes in the behavior and sometimes physiology of other individuals. [18] The composition of these chemicals often differs considerably between species, allowing lizards to tell whether the lizard that deposited the chemical was a member of the same or a different species. [17] Chemical secretions in some species (such as Iberian rock-lizards, Lacerta monticola ) also vary by individual, [19] so individuals can tell whether the lizard that produced a chemical is familiar or not. [19] [20]
Lizards that use chemical communication have highly developed olfactory systems to detect chemicals in the environment, [21] and often have femoral glands or pores on their back legs [22] to release chemicals. Such lizards sometimes drag their back legs or the lower half of their body against a surface to spread their chemical secretions. Tongue flicking is used to "taste" chemicals in the air and on various surfaces, such as rocks or logs that another lizard might have been sitting on. Chemicals can also be deposited through feces [23] —lizards have been observed defecating systematically throughout the area they live in, possibly chemically marking the boundaries of their territory. [23]
Lizards do not need to come into direct contact to communicate chemically. [24] Once a chemical has been released onto a surface, it stays until washed away or otherwise removed, and lizards may come into contact with it hours or days later. Thus, chemical communication is useful among lizards that live at relatively low population densities or do not come into close contact, and it is usually better suited to dry environments, as water can wash chemicals away.
Recent advances have dramatically increased our understanding of lizard chemical communication. [25] [26] [27] Further analysis of the composition of these chemicals will yield more information about the individuals that produce them and how they communicate in different contexts. [28] [29] [30]
The chemicals secreted by Podarcis hispanicus are generally more volatile and chemically stable than those of similar species. Chemosensory recognition is greater in males, as it allows them to identify specific females during breeding season and to recognize known neighbors and thus not perform anti-predator behaviors. It is also used in intra-sexual aggression. Male lizards release chemical stimuli from their femoral glands. [31]
Some lizards use direct or indirect touch as a form of communication. [9] Direct contact can occur in courtship, such as through nudging or licking, and in aggressive behavior—for many lizards, a fight may escalate to biting or bumping into one another. Species that engage in physical conflict often only resort to direct contact when other methods of deterring potential rivals have failed. In the case of courtship, some lizards, such as the male Komodo dragon ( Varanus komodoensis ), lick females to determine whether they are sexually receptive. [32] While this is direct touch, the male is also detecting chemicals in the female's body.
Some forms of tactile communication, such as vibrational, do not involve direct touch. [33] Some chameleon species communicate with one another by vibrating the substrate they are standing on, such as a tree branch or leaf. [34] Unique adaptations in ear and jaw morphology enable such lizards to detect these vibrations. [35] Lizards that live on easily moved substrates such as thin tree branches or leaves are more likely to use vibrational communication than lizards that live on substrates that do not transmit vibrations as easily, such as the ground or thick tree trunks.
This mode of communication is primarily limited to nocturnal geckos, many of which produce vocalizations during behavioral interactions such as male competition [2] [36] [37] or predator avoidance. [38] Another lizard, Liolaemus chiliensis , emits distress calls. Other lizards can produce vocalizations—for instance, when handled [2] —but most have not been observed to do so in the wild.
Lizards that use vocal communication need to produce vocalizations and need an appropriate auditory system to process the sounds.[ further explanation needed ] Vocal communication is well suited for nocturnal lizards or those that live in low-visibility habitats because it does not require coming into contact with or seeing other lizards.
Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.
Dactyloidae are a family of lizards commonly known as anoles and native to warmer parts of the Americas, ranging from southeastern United States to Paraguay. Instead of treating it as a family, some authorities prefer to treat it as a subfamily, Dactyloinae, of the family Iguanidae. In the past they were included in the family Polychrotidae together with Polychrus, but the latter genus is not closely related to the true anoles.
The Lacertidae are the family of the wall lizards, true lizards, or sometimes simply lacertas, which are native to Afro-Eurasia. It is a diverse family with at about 360 species in 39 genera. They represent the dominant group of reptiles found in Europe.
Anolis is a genus of anoles, iguanian lizards in the family Dactyloidae, native to the Americas. With more than 425 species, it represents the world's most species-rich amniote tetrapod genus, although many of these have been proposed to be moved to other genera, in which case only about 45 Anolis species remain. Previously, it was classified under the family Polychrotidae that contained all the anoles, as well as Polychrus, but recent studies place it in the Dactyloidae.
Anolis carolinensis or green anole is a tree-dwelling species of anole lizard native to the southeastern United States and introduced to islands in the Pacific and Caribbean. A small to medium-sized lizard, the green anole is a trunk-crown ecomorph and can change its color to several shades from brown to green.
Animal communication is the transfer of information from one or a group of animals to one or more other animals that affects the current or future behavior of the receivers. Information may be sent intentionally, as in a courtship display, or unintentionally, as in the transfer of scent from the predator to prey with kairomones. Information may be transferred to an "audience" of several receivers. Animal communication is a rapidly growing area of study in disciplines including animal behavior, sociology, neurology, and animal cognition. Many aspects of animal behavior, such as symbolic name use, emotional expression, learning, and sexual behavior, are being understood in new ways.
The brown anole, also known commonly as the Cuban brown anole, Bahaman anole, or De la Sagra's anole, is a species of lizard in the family Dactyloidae. The species is native to Cuba and the Bahamas. It has been widely introduced elsewhere, via the importation and exportation of plants where the anole would lay eggs in the soil of the pots, and is now found in Florida and other regions of the United States including southern Georgia, Texas, Louisiana, Tennessee, Mississippi, Alabama, Hawaii, North Carolina, and Southern California. It has also been introduced to other Caribbean islands, Mexico, and Taiwan.
Podarcis hispanicus, also known as Iberian wall lizard, is a small wall lizard species of the genus Podarcis. It is found in the Iberian Peninsula, in northwestern Africa and in coastal districts in Languedoc-Roussillon in France. In Spanish, this lizard is commonly called lagartija Ibérica.
Iberolacerta cyreni, commonly known as the Cyren's rock lizard, is a species of lizard in the family Lacertidae. The species is endemic to central Spain and is currently listed as endangered by the IUCN due to global warming. I. cyreni has evolved to exhibit key behavioral characteristics, namely individual recognition, in which a lizard is able to identify another organism of the same species, as well as thermoregulation.
The Iberian worm lizard, Mediterranean worm lizard, or European worm lizard is a species of reptile in the family Blanidae of the clade Amphisbaenia. The Iberian worm lizard is locally known as cobra-cega (Portuguese), culebrilla ciega (Spanish), and colobreta cega (Catalan), all meaning "blind snake". Recent studies into the mitochondrial and nuclear genomic data of 47 isolated B. cinereus populations show rather large sequence divergence between two apparent clades, leading some researchers to call for a division of the Iberian worm lizard into two species. While little is known of B. cinereus in comparison with some other reptile species, new insight is growing about this primitive, ancestral reptile.
Femoral pores are a part of a holocrine secretory gland found on the inside of the thighs of certain lizards and amphisbaenians which releases pheromones to attract mates or mark territory. In certain species only the male has these pores and in other species, both sexes have them, with the male's being larger. Femoral pores appear as a series of pits or holes within a row of scales on the ventral portion of the animal's thigh.
The Puerto Rican twig anole or dwarf anole is a species of small, arboreal anole endemic to Puerto Rico and primarily inhabiting the Cordillera Central from the Sierra de Cayey range in the Southeast to the central-western ranges of Maricao. A mostly grey to olive-brown bodied lizard, A. occultus is the smallest of the Puerto Rican anoles with a snout to vent length of 34–42 mm. In comparison to other twig anoles, A. occultus is extremely cryptic through its unique sleeping behaviors and mottled pattern. Sleeping behavior including site selection minimizes the probability of predator encounter along with A. occultus' extensive list of antipredator behaviors.
Anolis grahami, commonly known as the Jamaican turquoise anole and Graham's anole, is a species of lizard in the family Dactyloidae. The species is native to the island of Jamaica, and has also been introduced to the territory of Bermuda. It is one of many different species of anole lizards found in Jamaica. There are two recognized subspecies.
Anolis proboscis, commonly known as the horned anole, Ecuadorian horned anole or Pinocchio lizard, is a small anole lizard in the family Dactyloidae. A single male specimen was discovered in 1953 in Ecuador and formally described by Peters and Orces in 1956, but the species then went unreported until its rediscovery in 2004. Its currently known habitat is a small stretch of vegetation along an Ecuadorian highway. It has been classified as Endangered by the IUCN due to its restricted distribution and ongoing habitat loss.
Anolis vermiculatus, the Vinales anole or Cuban stream anole, is a species of lizard in the family Dactyloidae, endemic to Cuba.
Anolis eugenegrahami, the Eugene's anole or the black stream anole, is a critically endangered species of lizard in the family Dactyloidae. This semi-aquatic species is endemic to northern Haiti.
Anolis aquaticus, commonly known as the water anole, is a semi-aquatic species of anole, a lizard in the family Dactyloidae, native to southwestern Costa Rica and far southwestern Panama. The species demonstrates adaptations that allows it to spend periods of time underwater up to approximately a quarter of an hour, forming an air bubble which clings to its head and serves to recycle the animal's air supply while it spends time beneath the surface. Although highly unusual, similar adaptions and behavior are found in other species of semi-aquatic anoles.
Anolis evermanni, also known commonly as the emerald anole, Evermann's anole, and the small green anole, is a species of lizard included within the family Dactyloidae. A. evermanni is native to Puerto Rico, where it is mainly found in wet forests. A. evermanni is a medium-sized lizard and bright emerald-green in color. A. evermanni is studied for its behavior as well as the evolution of the family Dactyloidae. The group of lizards which are member species of the family Dactyloidae are known as anoles. Anoles are found throughout the Americas and are related to iguanas.
Anolis gundlachi, also commonly known as the yellow-chinned anole, Gundlach's anole, and the yellow-beard anole, is an oviparous, sexually dimorphic species of lizard in the family Dactyloidae. The species is endemic to Puerto Rico and lives in mountainous forests at high elevations. The diet of A. gundlachi consists mostly of insects. This species is also known for signaling other lizards through a modulated head bob display, with varying bobbing amplitudes and patterns based on an individual's distance from other lizards.
The sensory drive hypothesis is a hypothesis in population ecology that posits that when local environmental conditions differ between conspecific populations, communication systems will adapt to these conditions. Sensory drive predicts that both communication signals and perceptual systems will adapt to these local environmental conditions. Divergence will then occur based on the intensity and direction of selection on the mating signals and on the sensory systems acquiring information regarding predators, prey, and potential mates.