User:Bowman.1289/sandbox

This is my Sandbox. Wiki Project: Topic: Paedomorphosis Primary References: 1. Bhullar, B.-A. S., J. Marugan-Lobon, F. Racimo, G. S. Bever, T. B. Rowe, M. A. Norell, and A. Abzhanov. 2012. Birds have paedomorphic dinosaur skulls. Nature, advance online publication, doi:10.1038/nature11146. The authors look into the skull of the birds to explore just where they evolved from. They examine many characteristics of the bird skull and then relate those characters to that of the extinct theropod dinosaurs. They suggest that the birds skull; larger brains, predominant eyes, and a short face, have evolved through paedomorphosis. These characteristics seen in today’s bird skulls resemble embryo and juveniles of archosaurs. 2. Whiteman HH (1994). Evolution of facultative paedomorphosis. Quart Rev Biol 69: 205–221. When researching paedomorphosis salamanders always prove to be an interesting topic. The authors of this article investigated the variation of the evolution of paedomorphic salamanders metamorphic timing. They experimented to find certain alleles showed more rapid metamorphosis versus the expression of another allele showing a delayed process. They locate the expression the of these certain time affecting alleles at the specific TH-responsive loci. 3. Godfrey, L. R. and Sutherland, M. R. (1996), Paradox of peramorphic paedomorphosis: Heterochrony and human evolution. Am. J. Phys. Anthropol., 99: 17–42. doi: 10.1002/ajpa.1330990102 The author of this paper evaluates Gould’s hypothesis, and try to answer some of the questions mostly criticized. Gould’s hypothesis is a clock model for heterochronic processes and uses that model to focus on the growth and change in animals. These questions are all focused on neoteny, paedomorphosis, human evolution, and heterochrony. 4. Wehr, Paul, MacDonald, K, Linder, R, Yeung, G. 2001. Stabilizing and directional selection on facial paedomorphosis. Human Nature., 12: 383-402. doi: 10.1007/s12110-001-1004-z The author experiments to determine how the averageness determined by stabilizing selection versus facial paedomorphosis that is resulted by directional selection. The author looks into what and which drives the population. They set up an experiment to compare the effects on both directional and stabilizing selection on facial paedomorphosis. The results conclude that stabilizing selection influences facial paedomorphosis more so than directional. 5. Shea, BT. (1983). Paedomorphosis and neoteny in the pygmy chimpanzee. Science 222:521-522. doi: 10.1126/science.6623093 The pygmy chimpanzee has a predominate paedomorphic skull. Shea writes about the heterochronic process of neoteny in this paedomorphic skull, and how it relates to the pan paniscus in sexual dimorphism. The author also goes into the rates and timing of similar patterns of development in these species.

COPY OF 300 WORD INSERT INTO EXISTING WIKI PAGE( https://en.wikipedia.org/wiki/Neoteny ) UNDER ATTRACTIVE WOMEN'S FACES: A similar study was conducted on the attractiveness of males with the subject of the skull and its application in human morphology Paul Wehr and team (2001) utilized psychology and evolutionary biology to understand selection on facial features. Averageness has been a result of stabilizing selection whereas facial paedomorphosis or juvenile traits are a result of directional selection (Wehr, 2001). It is necessary at this point to define several terms to put them into practical time and space, as they pertain to this argument. The idea of directional selection as defined by Bergstrom and Dugatkin (2012) is when a single phenotypic trait is driven by selection toward fixation in a population (Bergstrom and Dugatkin, p. 218). In contrast, stabilizing selection is defined as being a scenario wherein both alleles are driven toward fixation in a population (or polymorphic, both alleles reaching equilibrium at a fixation) (Bergstrom and Dugatkin, p.221). To compare the effects of directional and stabilizing selection on facial paedomorphosis Wehr used graphic morphing to alter appearances to make faces appear more or less juvenile. The results concluded that the effect of averageness was preferred nearly twice over juvenile trait characteristics which indicates that stabilizing selection influences facial preference, and averageness was found more attractive than the retention of juvenile facial characteristics (Wehr, 2001). This follows the conclusions of the other study presented previously. It was perplexing to find that women tend to prefer the average facial features over the juvenile, because in animals the females tend to drive sexual selection by female choice and the red queen hypothesis. Some may hypothesize this is because in humans women tend to focus on social features including education, job status, family background, humor, and courtships. Experiments have found males tend to focus on the attractiveness of women, whereas women focus of overall quality and verbal interactions.


 * Wehr, Paul, MacDonald, K, Linder, R, Yeung, G. 2001. Stabilizing and directional selection on facial paedomorphosis. Human Nature., 12: 383-402. [Internet]. Cited on: 26 Oct 2014. Available from doi: 10.1007/s12110-001-1004-z
 * Bergstorm, Carl T. and Dugatkin, Lee Alan. “Evolution (Book, 2012).” W. W. Norton & Company, Inc. 2012. Cited on: 28 Oct 2014.

COPY OF FINAL DRAFT: The sexually mature stage of a specie that retains body features that were juvenile structures in an ancestral specie is a condition called paedomorphosis. There are two types of paedomorphosis. The first is entitled progenesis. Progensis is the process of early sexual maturation in an otherwise juvenile body (Bergstorm,2012). The second type is called neoteny. This entails a reduced rate of morphological development. Each of these conditions emphasize an aspect or type of heterochrony (Bergstorm,2012). The most noteworthy examples of paedomorphism involve various species of amphibians within which development is shunted in such a way that the larval form and aquatic habit endure as the organism reaches sexual maturity and, in turn, becomes capable of reproduction (Whiteman, 1994). The number of morphological features that are actually retarded may vary from one species to another, where only a single trait may be modified for a certain organism compared to another that expresses juvenilization for several traits. People, like the students in this class, exhibit differential neotenic body features that other, similar, adult primates do not. Additionally, species exist where morphological development is entirely obstructed. Juvenilization of the individual is holistic, but the organism is still capable of reproduction, in other words, the organism is sexually mature. Alterations of this nature, relating to the reproductive capabilities of the organism correlate to significant adaptive significance. From an evolutionary standpoint, the action of paedomorphism has the potential to, provided the right conditions, spur entirely new organisms. Paedomorphosis has proven to be a promising area of research, mainly involving fossil records, in evolutionary biology (Reece et al., 2005, p. 526). Evolutionary biologists can examine this condition in different species to conclude common ancestry. In 1928 W. Garstang coined the term (paedomorphosis) to better explain how evolution works. The years following proved to be quite interesting within the evolutionary community. Attempting to better understand the condition is best accomplished by examining the species who exhibit these patterns: primates and homo sapiens, salamanders, newts and birds. One of the most common examples of paedomorphosis can be seen in primates. Thomas Shea (1983), in his article Paedomorphosis and neoteny in the pygmy chimpanzee, examines the predominate paedomorphic skull. He states the skull relates to the pan paniscus by sexual dimorphism. The pygmy chimpanzee has retained the juvenile skull, and Shea further explains the process of heterochrony (Shea, 1983). As mentioned above, heterochrony is an evolutionary change in the rate or timing of developmental events. A species or more simply an organism’s shape depends on the relative growth rates of different body parts during development (Reece et al., 2005, p. 525). Mutations can cause changes to those rates which in turn alter the adult form substantially. This alteration is the paedomorphic condition of retention of juvenile traits. Retaining a juvenile skull is also seen in homo sapiens from chimpanzees. When examining the chimpanzee fetus skull in comparison to a fetus and adult human skull there is clearly a positive correlation between the two. It is understood that mutations that slowed the growth of the jaw relative to other parts of the skull produced this paedomorphic condition (Mitteroecker et al., 2004). Philipp Mitteroecker and team (2004) conducted research on this very topic. Mitteroecker has shown in his research that Homo sapiens craniofacial morphology is distinct from Pan, Gorilla, and Pongo in shape and size-shape space (2004). They not only conducted fossil examining of the cranial cavities but they also went deeper into the molecular level. The molecular studies concluded that Homo and Pan are more closely related. Thus, early affected ontogeny gave rise to large morphological differences in adults. Human craniofacial morphology was the result of small genetic differences between humans and chimpanzees which was the direct result of Mitteroecker’s research. Continuing with the subject of the skull and its application in human morphology Paul Wehr and team (2001) utilized psychology and evolutionary biology to understand selection on facial features. Averageness has been a result of stabilizing selection whereas facial paedomorphosis is a result of directional selection (Wehr, 2001). It is necessary at this point to define several terms to put them into practical time and space, as they pertain to this argument. The idea of directional selection as defined by Bergstrom and Dugatkin (2012) is when a single phenotype is driven by selection toward fixation in a population (p. 218). In contrast, stabilizing selection is defined as being a scenario wherein both alleles are driven toward fixation in a population (or polymorphic, both alleles reaching equilibrium at a fixation) (p.221). To compare the effects of directional and stabilizing selection on facial paedomorphosis Wehr used graphic morphing to alter appearances to make faces appear more or less juvenile. The results concluded that the effect of averageness was preferred nearly twice over juvenile trait characteristics which indicates that stabilizing selection influences facial preference, and averageness was found more attractive than the retention of juvenile facial characteristics (Wehr 2001). An abundant amount of research into paedomorphosis has been conducted while studying newts and salamanders. These two organism groups are studied more prevalently than any others in the field of paedomorphosis because of their clear adherence and manifestation of this condition. In essence, an alteration of heterochrony that occurred at some point in time manifested phenotypically distinct traits in certain species of salamanders. These salamanders, such as the axolotl salamander, possessed retention of gills and other larval features that were expressively variant from those of their ancestors, despite having only a single locus altered (Reece et al., 2005, p. 526). Two articles directly affirming this idea are the Evolution of Facultative Paedomorphosis and Evolutionary Ecology of Facultative Paedomorphosis in Newts and Salamanders, by Howard Whiteman and Mathieu Denoel, respectively. In his article, Whiteman (1994) proposed a mechanism of paedomorphosis driven by the environment titled Facultative Paedomorphosis. In this mechanism, Whiteman cites an example of a salamander whose larval traits had a high level of fitness in an aquatic environment. Environmental induced phenotypes that retained the larval traits became genetically fixed in the population as a result of having higher fitness (Whiteman, 1994). Mathieu Denoel and his colleagues (one of which was actually Howard Whiteman) happened upon this same idea in another series of research trials. He noted that there is a multitude of salamanders and newts that exhibit facultative paedomorphosis. In his publication, Denoel states “paedomorphosis has been observed in fifty-seven species of newts and salamanders, distributed in nine of the ten recognized families” (2005). Holistically, more than 10% of all salamander species exhibit paedomorphic developmental pathways (Denoel 2005). Both publications were unified by an underlying theme, the role of the environment.

Another example of paedomorphosis can be examined in birds. Bhart-Anjan S. Bhullar Paedomorphmic pathways can be viewed in the characteristics of the bird skull and then relate those characters to that of the extinct theropod dinosaurs (Bhullar,2012). They suggest that the birds skull; larger brains, predominant eyes, and a short face, have evolved through paedomorphosis. These characteristics seen in today’s bird skulls resemble embryo and juveniles of archosaurs (Bhullar, 2012). Paedomorphism occurred in our backyard, literally. The Ohio region is the hub for trilobite fossil hunting. Columbus, Ohio limestone yields several species of its own. Trilobites were an exclusive marine group of arthropods that existed in the Cambrian Period and lived through the Paleozoic Period, and became extinct in the Permian Period. They were considered one of the most successful of all ancestral animals, excelling for over 270 million years. H.B. Whittington has proposed proparian trilobites may have come to be by paedomorphosis. Whittington believes an early Upper Cambrian type of species named Schmalenseeia exhibits paedomorphic traits, such as thin exoskeleton, that was retained from planktic species (Whittington, 1981). Relationships are minute for the reason trilobites have been extinct for 250 million years, and are survived only by their fossilized remains. It is important when studying a topic to make real world measure of it. By doing so, one is able to fully apply conceptual data to real world attributes and scenarios. In the case of paedomorphosis, conceptual understanding is certainly best exemplified through the real world measures that account for and define the condition. From an evolutionary standpoint, the retroactive nature of paedomorphic pathways describe an astonishing relationship between environment and organism, illustrating the power of the environment to over express and not express juvenile phenotypic traits, as time progresses. “To put it simply, the phenomenon of paedomorphosis indicates that in certain circumstances evolution can retrace its steps, as it were, along the path which led to a dead end, and make a fresh start in a new, more promising direction. (Arthur Koestler)” References Bergstorm, Carl T. and Dugatkin, Lee Alan. “Evolution (Book, 2012).” W. W. Norton & Company, Inc. 2012. Cited on: 28 Oct 2014.

Bhullar, Bhart-Anjan S., Marugan-Lobon, Jesus., Racimo, Fernando., Bever, Gabe S., Rowe, Timothy B., Norell, Mark A., and Abzhanov, Arhat. 2012. Birds have paedomorphic 		dinosaur skulls. Nature., 487: 223-226. [Internet]. Cited on: 28 Oct 2014. Available from: doi:10.1038/nature11146

Denoel, Mathieu., Joly, Pierre., and Whiteman, Howard. 2005. Evolutionary Ecology of Facultative Paedomorphosis in Newts and Salamanders. Quart Rev Biol 80, pp. 663-671. [Internet]. Cited on: 28 Oct 2014. Available from: doi:10.1017/S1464793105006858

Mitteroecker, Philipp., Gunz, Philipp., Bernhard, Markus., Schaefer, Katrin., and Bookstein, Fred. (2004). Comparison of cranial ontogenetic trajectories among great apes and 		humans. Journal of Human Evolution. [Internet] Cited on: 26 Oct 2014. Available from: http://theoretical.univie.ac.at/fileadmin/user_upload/dep_theoretische_biologie/philipp/Mitteroecker_etal_2004.pdf

Reece, Jane B., Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson. "Campbell Biology (Book, 2011).” Pearson, 2005. Cited on: 27 Oct. 		2014.

Shea, BT. 1983. Paedomorphosis and neoteny in the pygmy chimpanzee. Science 222:521-522. [Internet] Cited on: 26 Oct 2014. Available from doi: 10.1126/science.6623093

Wehr, Paul, MacDonald, K, Linder, R, Yeung, G. 2001. Stabilizing and directional selection on facial paedomorphosis. Human Nature., 12: 383-402. [Internet]. Cited on: 26 Oct 2014. Available from doi: 10.1007/s12110-001-1004-z

Whiteman, Howard. 1994. Evolution of facultative paedomorphosis. Quart Rev Biol 69: 205–221. [Internet] Cited on 28 Oct 2014. Available from: http://www.jstor.org/discover/10.2307/3037717?uid=3739840&uid=2&uid=4&uid=3739256&sid=21104532380801

Whittington, H. B. 1981. Paedomorphosis and cryptogenesis in trilobites. Geological Magazine.,Volume 118/ Issue 06/ pp. 591-602. [Internet]. Cited on 28 Oct 2014. Available from: 		DOI: http://dx.doi.org/10.1017/S0016756800033823