User:Mohamed.156/sandbox

User:Mohamed.156/sandbox Topic: The Evolution of morphological changes in lizards. References: Collar D.C., Schulte II J.A., O’meara B.C. & Losos J.B. 2010. Habitat use affects morphological diversification in dragon lizards. Evol. Bio. 5(23), 1033-1049. (DOI: 10.1111/j.1420-9101.2010.01971.x) The authors, researchers reconstructed four ancestral habitats of agamid lizards and constructed morphological models to test their hypotheses that habitat types contribute differently to the process of evolution. Their result were as follows, there were slower rates of evolution in lizards who occupied a rock-dwelling environment as well as model-average rate estimate overall. Wiens J.J. 2000. Decoupled evolution of display morphology and display behaviour in phrynosomatid lizards. Linn. Soc. 70(4), 597-612. (DOI: 10.1006/bijl.1999.0419) The author and researcher tested previous experiment about display morphology against behavioral and morphological data for 59 different taxa of phrynosomatid lizards using phylogenic comparative methods. His results were as follows, he observed significant variations in display morphology and behavioral morphology within the taxa suggesting a relatively unrelated evolution of display and behavioral morphology. The two traits were not closely coupled together. Hertz P.E., Arima Y., Harrison A., Huey R.B., Losos J.B. & Glor R.E. 2012. Asynchronous evolution of physiology and morphology in Anolis lizards. Org. Evol. 67(7), 2101-2113. (doi:10.1111/evo.12072) The authors and researcher test whether or not different adaptive traits of Anolis lizards are closely related in their evolution. They investigate phylogenic traits related to thermal biology and morphology in the Anois taxa. Their results were as follows, they found that thermal biology showed more divergence in recently diverged Anolis lizard than morphology. They also found that thermal biology divergence usually follows morphological divergence. Bauwens D. & Garland Jr. T. 1995. Evolution of sprint speed in lacertid lizards: morphological, physiological, and behavioral covariation. Evol. 49(5), 848-864. The authors and researcher at the Institute of Nature Conservation in Hasselt Belgium test for correlations in morphological, physiological and behavioral characteristics that influence sprint speed in a clade of lacertid lizards. Their analysis yielded increased sprinting speed was related to the evolution of longer hind limbs relative to body size and higher optimum physiological temperature. Irschick D.J. 2012. Evolutionary Approaches for Studying Functional Morphology: Examples from Studies of Performance Capacity. Integr. Comp. Biol. 42 (2), 278-290. (doi: 10.1093/icb/42.2.278) The author and researcher test how behavior of Caribbean Anolis lizards affects the relationship between their morphology and performance. He found that that avoid using perches to maximize their speed. Also species with faster speed use a greater range in habitats. He found that their behavior mimics their abilities to sprint faster on broad surfaces and move effectively on narrow surfaces.

https://en.wikipedia.org/wiki/Anolis The anolis lizards that are less susceptible to predation are those that have a dewlap that has both the scales and the skin in between match the expected pale gray or white like color of its ventral surface. Fitch H.S. & Hillis D.M. 1984. The anolis dewlap: Interspecific variability and morphological associations with habitat. Copeia, 1984(2), 315-323. The anolis lizard morphological deviation that exist do to habitat differentiation is an important topic that should be covered The fertility success of anolis lizards associated with environment conditions would also be an interesting topic to pursue. The variability in the locomotion of anolis lizards and how it evolved over time is a topic that I don’t see discussed every often. Would that be something you would consider?

Final Paper The evolution of morphological changes in lizards When it comes to the evolution of lizards there are many things to consider such as the environmental variants, habitat openness and the role of divergent evolution. How did the vast forms of morphological differentiations evolve? Thing such as sprint speed, tongue variability, performance variability, limb variation and changes in thermal biology have been readily studied for centuries. In order to understand how variations of multiple lizard species morphologies evolved to exist they must first be compared to the evolution of other functions such as thermal biology. Examining the relations between morphology and other aspect of lizards may explain if morphology variation arose due to significant changes elsewhere in lizard species. Natural selection plays an important role when deciphering the relationship between form and function of particular lizard species. When considering lizard locomotion, variation in ecology significantly affect what attributes will be selected to increase overall performance. The level of adaption to their environment will decide what locomotor skill best fits that lizard species. The gekkotan lizards for example vary significantly in their form and function. The Gecko gekko are well known for their climbing ability so they possess large claws and adhesive lamellae under their toes. They are flattened from the top of their heads downward and their limbs stretch wide bringing the center of their body closer to whatever they are climbing. Eublepharis macularius (otherwise known as the leopard gecko) on the other hand are ground dwellers who inhabit the desert. Their bodies are lifted from the ground to decrease contact and they are not as flattened. All of these characteristics are beneficial to each species of lizard making them more equipped to maneuver their habitat (Aerts et.al., 2000). Furthermore, Laurie Vitt and his colleagues at the Oklahoma Museum of Natural History performed an experiment in which they compared the morphologies of two Tropidurus hispidus tropical lizards that inhabit areas that are very close in proximity. What they found was that Tropidurus who inhabited the savanna had a larger diversity in microhabitats than Tropidurus that inhabited the rock outcrop. The Tropidurus that inhabited outcrops seemed to exhibit flatter bodies due to them hiding from predation in rock crevices. They also possess longer hind limbs for increased speed. DNA sequencing proved that the two Tropidurus lizards were indeed closely related which means that the features of the Tropidurus hispidus that inhabit the rock outcrops are derived (Vitt et.al., 1997). Morphological divergence occurred to increase the performance of Tropidurus inhabiting outcrops by making them faster and flatter so they can quickly avoid predation and seek refuge in the rock crevices. To further go into detail about the importance of morphological design and its contributions to performance, Brett Goodman from the School of Tropical Biology at James Cook University in Queensland Australia performed a compelling experiment. He set out to quantify the differences in morphology and behavior during escape and the levels of performance including climbing, clinging and jumping abilities of Carlia scirtetis lizards and Carlia mundivensis lizards which are two closely related lizards. These lizards inhabited similar rocky habitats with small variability. The habitat of Carlia scirtetis had large boulders and regular surfaces as well as being open while Carlia mundivensis habitat had small boulders and irregular surfaces as well as containing undergrowth and leaf litter. The results of the experiment were as follows, C.scirtetis had longer limbs and toes as well as greater sprint speed and greater clinging ability and climbing ability. C. scirtetis would let a predator get closer before escaping and escape to further distances. Also the direction that the predator is approaching from plays an important role with lizards escaping when the predator is further away if the predator is coming from above. C. mundivensis had greater climbing speed compared to sprinting speed and shorter limbs. There seemed to be no variation in the jumping ability between the lizards (Goodman, 2007). The results of Goodman’s experiment show that there are clear morphological tradeoffs in these lizards so they can perform well in their habitat. Take for example the C. Scirtetis lizards that evolved faster climbing and sprinting speed thereby increasing limbs size to best fit their open habitats with less vegetation and larger boulders so they can escape predation better. The C. mundvensis lizards on the other hand do not witness any tradeoffs. Scientist D.C. Collar and his colleagues toke a more practical approach while studying Agamidae lizards (otherwise known as dragon lizards). In their search to find how habitat variation may lead to large diversification, they relied on phylogenetic analysis, ancestral state reconstructions of over 90 species and models of evolution. In their phylogenetic analysis they found strong monophyly between southwest Asian and African dragon lizards. Also a clade of Asian dragon lizards and ones from Australian and New Guinea are sister groups. For the ancestral reconstruction, they found that 99% of reconstruction shows various origins of rock-dwelling and terrestrially, 91.6% show one or more origins of arboreality. The construction of a rate model shows slower evolutionary rates in species living in rock-dwelling and arboreal habitats than in species living in terrestrial and semi-arboreal regions. Terrestrial species have the fastest rate of evolution, semi-arboreal have intermediate rate of evolution and rock-dwelling and arboreal have equally slow rates of evolution (Collar et.al., 2010). John Wiens, a researcher at the Carnegie Museum of Natural History in Pittsburgh Pennsylvania wanted to relate display morphology to behavioral morphology. He began by reconstructing previous experiments about display morphology against behavioral and morphological data for 59 different taxa of phrynosomatid lizards using phylogenetic comparative methods. His results were as follows, he observed significant variations in display morphology and behavioral morphology within the taxa suggesting a relatively unrelated evolution of display and behavioral morphology. The two traits were not closely coupled together (Weins, 1999). His results show that behavioral morphology and display morphology evolved independent of one another. This is an example of divergent evolution in which certain characteristics do not evolve together in closely related species. Furthermore, researcher Paul Hertz and a group of researchers from various universities, tested whether or not different adaptive traits of Anolis lizards are closely related in their evolution. They investigate phylogenic traits related to thermal biology and morphology in the Anois taxa. Their results were as follows, they found that thermal biology showed more divergence in recently diverged Anolis lizard than morphology. They also found that thermal biology divergence usually follows morphological divergence (Hertz et. al., 2013). This experiment shows that thermal biology is very environment driven while certain morphological features derived from ancestral traits are maintained in Anois lizards Researcher Dirk Bauwe along with colleagues at the Institute of Nature Conservation in Hasselt Belgium test for correlations in morphological, physiological and behavioral characteristics that influence sprint speed in a clade of lacertid lizards. Their analysis yielded increased sprinting speed was related to the evolution of longer hind limbs relative to body size and higher optimum physiological temperature. Increased sprinting speed led to decreased thermal sensitivity. This means that these lizards can potentially run at maximum speed in a variety of temperatures. (Bauwe et. al., 1995). Researcher Duncan Irschick tested how the behavior of Caribbean Anolis lizards affects the relationship between their morphology and performance. He found that Anolis lizards avoid using perches to maximize their speed. Also species with faster speed use a greater range in habitats. He found that their behavior mimics their abilities to sprint faster on broad surfaces and move effectively on narrow surfaces. He correlated morphological changes to fitness and found that lizards that were best adapted to their environment had overall better fitness and reproduction rates (Irschick, 2002). This is yet another experiment that emphasizes the importance of morphology to good performance. In conclusion there have been many countless experiments on the importance of morphology to survival in particular lizard habitats that have produced similar result. A large portion of the experiments focused on how morphological variation is important to performance and behavior. It seems that in certain lizard species such as Tropidurus hispidus having flattened bodies is beneficial because it increases their ability to hide in rock crevices. This will then increase their ability to better evade predators. Natural selection is the main driving force for determining which morphological features will be kept for a lizard species. Adaptation to their environment will make sure that they behave accordingly when they are approached by a predator.

References Aerts P., Van Damme R., Vanhooydonck B., Zaaf A. & Herrel A. Lizard locomotion: how morphology meets ecology. Ned. J. Zool. 2000;50(2):261-277. Bauwens D. & Garland Jr. T. Evolution of sprint speed in lacertid lizards: morphological, physiological, and behavioral covariation. Evol. 1995;49(5): 848-864. Collar D.C., Schulte II J.A., O’meara B.C. & Losos J.B. Habitat use affects morphological diversification in dragon lizards. Evol. Bio. 2010;5(23): 1033-1049. Goodman B.A. Divergent morphologies, performance, and escape behaviour in two tropical rock-using lizards (Reptilia: Scincidae). Bio. J. Linn. Soc. 2007;91:85-98. Hertz P.E., Arima Y., Harrison A., Huey R.B., Losos J.B. & Glor R.E. Asynchronous evolution of physiology and morphology in Anolis lizards. Org. Evol. 2012;67(7): 2101-2113. Irschick D.J. Evolutionary Approaches for Studying Functional Morphology: Examples from Studies of Performance Capacity. Integr. Comp. Biol. 2012;42 (2):278-290. Laurie J.V., Caldwell J.P., Zani P.A. & Titus T.A. The role of habitat shift in the evolution of lizard morphology:evidence from tropical Tropidurus. Proc. Natl. Acad. Sci. USA. 1997;94:3828-3832. Schwenk K. &Throckmorton G.S. Functional and evolutionary morphology of lingual feeding in squamate reptiles: phylogenetics and kinematics. J. Zool., Lond. 1989;219:153-175   Wiens J.J. Decoupled evolution of display morphology and display behaviour in phrynosomatid lizards. Linn. Soc. 2000;70(4): 597-612.

Edits Closely related, recently diverged anole lizards exhibited more divergence in thermal biology than in morphology. These anole lizards are thought to have the same structural niche and have similarities in their size and shape. However they inhabited different climatic niches in which there was variability in temperature and openness of the environment. This suggests that thermal physiology is more associated with recently diverged anole lizards. Hertz P.E., Arima Y., Harrison A., Huey R.B., Losos J.B. & Glor R.E. Asynchronous evolution of physiology and morphology in Anolis lizards. Org. Evol. 2012;67(7): 2101-2113.Losos, J. B. 2009. Lizards in an evolutionary tree: ecology and adaptive radiation of anoles. University of California Press, Berkeley, CA. https://en.wikipedia.org/wiki/Anolis