Editing Anolis (section)

==Dewlap==
The dewlap is a flap of skin found beneath the jaw or throat of ''Anolis'' lizards. It can present in a variety of colorations, and is most present in male anoles. The dewlap is extended by means of the hyoid muscles in the throat, and can be flashed in a "pulse" pattern where the flap is extended repeatedly, or a "moving flag" pattern, where the lizard flashes it continuously while bobbing up and down.<ref name="Persons Fleishman Frye Stimphil 1999 pp. 585–607">{{cite journal | last1=Persons | first1=M. H. | last2=Fleishman | first2=L. J. | last3=Frye | first3=M. A. | last4=Stimphil | first4=M. E. | title=Sensory response patterns and the evolution of visual signal design in anoline lizards | journal=Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology | publisher=Springer Science and Business Media LLC | volume=184 | issue=6 | date=1999-07-05 | issn=0340-7594 | doi=10.1007/s003590050358 | pages=585–607| s2cid=21160410 }}</ref> The coloration of the dewlap is caused by two pigments, [[pterin]]s and [[carotenoid]]s. Pterin pigments are compounds synthesized from [[guanine]], whereas carotenoids are pigments acquired from the diet.<ref>{{cite journal | last1=Steffen | first1=John E. | last2=McGraw | first2=Kevin J. | title=Contributions of pterin and carotenoid pigments to dewlap coloration in two anole species | journal=Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology | publisher=Elsevier BV | volume=146 | issue=1 | year=2007 | issn=1096-4959 | doi=10.1016/j.cbpb.2006.08.017 | pages=42–46| pmid=17056290 }}</ref> Both cause the red-yellow hues most commonly found in ''Anolis'' lizard dewlaps. The function of the dewlap in ''Anolis'' lizards has been a topic of debate for centuries. It is thought that the dewlap is flashed as a visual signal for other competing males, or as a courtship signal for single females. It has also been hypothesized that the dewlap serves as a signal for sex recognition.<ref name="Sigmund 1983 p. 137">{{cite journal | last=Sigmund | first=William R. | title=Female Preference for Anolis carolinensis Males as a Function of Dewlap Color and Background Coloration | journal=Journal of Herpetology | publisher=JSTOR | volume=17 | issue=2 | year=1983 | pages=137–143 | issn=0022-1511 | doi=10.2307/1563454 | jstor=1563454 }}</ref>

[[File:Anolis carolinensis 207880066.jpg|thumb|Pink dewlap on an Anolis carolinensis lizard]]

===Initial studies===
The first study done on dewlap function was by Mertens (1926). The initial assumption was that the dewlap was flashed as a method of [[sexual selection]], and that the males would use it in order to attract females. It is hypothesized that female ''Anolis'' lizards are more attracted to males who flash their dewlaps more often, or have more brightly colored dewlaps.<ref name="Sigmund 1983 p. 137" /> This was then challenged by the hypothesis that males flashed their dewlap as a way to threaten other males in the area.<ref>{{cite journal | last1=NOBLE | first1=G. K. | last2=BRADLEY | first2=H. T. | title=The Mating Behavior of Lizards; ITS Bearing on the Theory of Sexual Selection | journal=Annals of the New York Academy of Sciences | publisher=Wiley | volume=35 | issue=1 | year=1933 | issn=0077-8923 | doi=10.1111/j.1749-6632.1933.tb55365.x | pages=25–100| bibcode=1933NYASA..35...25N | s2cid=85270929 }}</ref> During intermale fights, dewlaps are flashed. More currently, many studies have been done on the dewlap as a function for [[Intra-species recognition|species recognition]], with focus on the relationship of the contrast between dewlap color and environment.

===Relationship with environment===
The dewlap comes in a variety of colors, including yellow, blue, and red. It was previously believed that the color of the dewlap is what mattered most in interlizard interactions, but it has since been found that there exists a relationship between habitat light conditions and dewlap color.<ref>{{cite journal | last1=Fleishman | first1=Leo J. | last2=Perez-Martinez | first2=Christian A. | last3=Leal | first3=Manuel | title=Can Sensory Drive Explain the Evolution of Visual Signal Diversity in Terrestrial Species? A Test with ''Anolis'' Lizards | journal=The American Naturalist | publisher=University of Chicago Press | volume=200 | issue=2 | date=2022-08-01 | issn=0003-0147 | doi=10.1086/720267 | pages=236–249| pmid=35905402 | s2cid=247884850 | doi-access=free }}</ref><ref name="Persons Fleishman Frye Stimphil 1999 pp. 585–607" /> This means that, rather than the color being of importance, it is the contrast of the dewlap against the background of its environment that best visually signals to other lizards. There have been many methods used to determine this. Persons et. al (1999) found that the probability of a dewlap showing being detected goes up with the contrast of dewlap against the background. They determined this by measuring the number of times a "positive response" of the lizard's eyes turning towards a flashed dewlap occurred among different background contrasts. Similarly, Leal and Fleishman (2002) found that the light conditions in which a lizard displays its dewlap affects the probability of it being visually detected. They did this by measuring the UV spectral reflectance of dewlaps in ''Anolis cristatellus'' lizards using a [[spectroradiometer]], then measuring the spectral sensitivity of the lizards’ retinal responses using electroretinographic (ERG) flicker photometry.<ref name="Leal, M 2002. pp. 351">{{cite journal | last1=Leal | first1=Manuel | last2=Fleishman | first2=Leo J. | title=Evidence for habitat partitioning based on adaptation to environmental light in a pair of sympatric lizard species | journal=Proceedings of the Royal Society of London. Series B: Biological Sciences | publisher=The Royal Society | volume=269 | issue=1489 | date=2002-02-22 | issn=0962-8452 | doi=10.1098/rspb.2001.1904 | pages=351–359| pmid=11886622 | pmc=1690909 }}</ref>

===Evolution===
''Anolis'' lizards have emerged to be a good example of [[adaptive radiation]]. The difference in dewlap morphology among ''Anolis'' lizard populations demonstrates this phenomenon. ''Anolis'' lizards have the ability to adapt to different areas of the environment in a way where multiple species can coexist effectively. The amount of vegetation in an environment affects the amount of light absorbed. Studies have shown that lighting affects the dewlap’s function as a visual signal. The diversity in vegetation in ''Anolis'' lizards’ environments has caused a similar diversity in dewlap morphology, as different species of anoles adapt to the lighting conditions in their environment.<ref name="Leal, M 2002. pp. 351"/> The ability for a lizard to signal effectively also means it is able to defend its territory and attract mates more effectively, making it a good competitor.

The relationship between background contrast and visual signals also suggests that there exists a [[coevolution]] between the signals and sensory systems of ''Anolis'' lizards.<ref>{{cite journal | last1=Leal | first1=Manuel | last2=Fleishman | first2=Leo J. | title=Differences in Visual Signal Design and Detectability between Allopatric Populations of''Anolis''Lizards | journal=The American Naturalist | publisher=University of Chicago Press | volume=163 | issue=1 | year=2004 | issn=0003-0147 | doi=10.1086/379794 | pages=26–39| pmid=14767834 | s2cid=5650723 }}</ref> The environmental diversity of Anolis habitats causes a diversity in the recognition of individuals. Sensory systems must be able to effectively pick up on dewlap signals, thus coevolving with the changes in dewlap characteristics.

One of the main limitations to these theories is that of [[gene flow]]. Population genetic theory says that gene flow can counteract evolutionary adaptations made and prevent signal divergence, due to an influx of abnormal alleles into the new population.<ref>{{cite journal | last1=Dieckmann | first1=Ulf | last2=Doebeli | first2=Michael | title=On the origin of species by sympatric speciation | journal=Nature | publisher=Springer Science and Business Media LLC | volume=400 | issue=6742 | year=1999 | issn=0028-0836 | doi=10.1038/22521 | pages=354–357| pmid=10432112 | bibcode=1999Natur.400..354D | s2cid=4301325 | url=http://pure.iiasa.ac.at/id/eprint/5926/1/IR-99-013.pdf }}</ref> This causes a genetic homogenization and challenges the idea that dewlap morphology in ''Anolis'' lizards and their sensory systems have coevolved.