User:Amrania.1/sandbox

Samir Amrania EEOB 3310: Wikipedia Project Research Topic: Early evolutionary forces exerted by humans on Canis lupus which produced the genotypic and phenotypic changes leading to Canis familiaris (domestic dog). Annotated Bibliography Morey, Darcy F. "The Early Evolution of the Domestic Dog." American Scientist. 82.4 (1994). Print. This article delves into the history of the evolution of what we know today as the domesticated dog. The article addresses the misconception that the domestication of the dog was a purposeful act by humans (as many other instances of domestication of mammals were). It discusses the fact that the wolves of the time began to follow humans as a source of extra food, and that humans likely allowed this because the added protection was mutually beneficial for them. The article goes into discuss the implication of this first evolution/domestication event for ones in the future, and how we shaped other mammals to fit our needs. "Phylogenetic Relationships, Evolution, and Genetic Diversity of the Domestic Dog."Journal of Heredity. 90.1 (1999): 71. Print. This article is focused on the evolution of the dog from a more genetic standpoint. It analyzes the phylogeny of animals closely related to the dog and discusses the changes that would have had to occur, specifically those that were caused by human pressures. These include the basic changes like shortening of the snout over time, but also includes a discussion of how so much phenotypic variation occurred, compared to how much genotypic change happened. Rodney, L H. "Unraveling the Mysteries of Dog Evolution." Bmc Biology. 8.1 (2010). Print. In this article a study of QTL mapping and the underlying sources of morphological change in the wolf to the dog was performed. The article used this data to suggest that the wolf population must have gone through a bottleneck in becoming the dog, which accounts for the relatively low genetic diversity they exhibit. A specific example presented in the article goes over how the size of domesticated dog could change so vastly. Vilà, C, P Savolainen, JE Maldonado, IR Amorim, JE Rice, RL Honeycutt, KA Crandall, J Lundeberg, and RK Wayne. "Multiple and Ancient Origins of the Domestic Dog."Science (new York, N.y.). 276.5319 (1997): 1687-9. Print. This article examines the multiple possible origins of the evolution of the domestic dog. It discusses a variety of different forces that could have been indirectly exerted by humans that caused selection to occur. One of these forces was that the dogs who had an affinity for starch in food would have followed nomadic humans around more and would have been the ones to breed and eventually become domesticated. Wayne, Robert K, and Elaine A. Ostrander. "Origin, Genetic Diversity, and Genome Structure of the Domestic Dog." Bioessays. 21.3 (1999): 247-257. Print. In this article, the evolution of domesticated dog is broken down into its basic origins. This includes a discussion of why the canine was the first mammal to be domesticated by humans (although indirectly). The article also goes into how specific the selection for traits was in dogs, how little actually needed to change and the reason why dogs and wolves can still interbreed.

https://en.wikipedia.org/wiki/Ancient_dog_breeds

Potential Article Improvements:

As an article about ancient dog breeds, a section on the primary morphological changes that began to differentiate dogs from wolves could be added, this would help detail what characteristics really defined the ancient dog (such as shortening of the snout or the shrinking of brain cavity).

Another addition that could potentially be made to improve the article would be a section elaborating on the specific genotypic differences and similarities between ancient dogs and their wolf ancestors mentioned in the introduction of the article along with an updated/more complete cladogram.

A third alteration to the article could be the addition of a section on the behavior of the ancient dog that favored its coevolution and mutualistic relationship with humans. This would offer more insight into the origin of the traits we see so exaggerated in modern dogs.

Sentence:

One early morphological difference that separated dogs and their wolf ancestors was the shrinking of the brain cavity, specifically in areas of the limbic system that deal with flight or flight response, which would have allowed humans and dogs to interact in closer proximity.

Citation: Schoenebeck, J. J.; Ostrander, E. A. (8 February 2013). "The Genetics of Canine Skull Shape Variation". Genetics 193 (2): 317–325. doi:10.1534/genetics.112.145284.

FINAL DRAFT:

The origin and existence of Canis lupus familiaris, or as it is more commonly known “the dog”, holds with it a litany of important evolutionary considerations which are evident to us even today. Dogs as a species diverged from their wolf ancestors, Canis lupus, around 33,000 years ago in what is now known as Eastern Europe (Larson et al. 2012). The unique characteristic about this speciation event was that the selective pressure primarily responsible for it was humans. Normally when humans are the selective pressure responsible for bringing about a variety of organism directly beneficial to us, it is called domestication (Driscoll et al. 2009). The important distinction in the case of dogs is that the majority of the domestication event was unintentional on the part of the human (Driscoll et al. 2009). Yet, this unintentional domestication resulted in what is the most highly coevolved mammalian species present in human history (Wang et al. 2013). At the time that dogs diverged from the wolf, humans were nomadic hunter-gatherers who had not yet domesticated (or attempted to domesticate) any another animal, as humans did not remain in one place for long enough to raise or keep animals (Driscoll et al. 2009). Still, humans indirectly spurred the speciation event that caused wolves to eventually become the dog. Genetic analysis shows that one of the primary mechanisms underlying the speciation began with mutations that randomly occurred in wolf genes AMY2B, MGAM and SGLT1 for independent populations (Axelsson et al. 2013). The mutations increased the expression of these gene loci by nearly 7.4 fold, which conferred the ability to much more effectively digest and utilize nutrients from starches and fats (Axelsson et al. 2013). The implications of these mutations can be seen in archeological records that show that dog ancestors began to follow groups of nomadic humans and eat the more starchy and fatty leftovers of the foods humans ate (Axelsson et al. 2013). The fossils of these dog ancestors were found to show that the proto-dogs followed groups of nomadic humans, and with mitochondrial DNA evidence, were even found to have the same food scraps in their teeth that the nomadic humans did (Axelsson et al. 2013). This simple change in diet began a cascade of events that, over time, furthered the speciation of wolf into dog. The wolves that followed humans underwent sympatric speciation by beginning to mate more and more exclusively with one another instead of with the other wolves living in the same geographical area (Vilà et al. 1997). Among the wolves following humans, further random mutations discovered by QTL (quantitative trait loci) mapping caused changes in the morphology of the wolf brain (Wayne 2012). The areas of the limbic system having to do with fight or flight responses began to shrink by 20-40%; enabling wolves to be less afraid of humans and more willing to get closer to them (Wayne 2012). The wolves that were less afraid of humans had a competitive advantage over the wolves who were still afraid of humans because they were able to consume more of the food scraps that humans left behind, and were therefore healthier and more fit to breed (Rodney 2010). In conjunction with the brain, the morphology of the wolf snout began to change as well. The snout and teeth became shorter and more adapted to eating a variety of different foods rather than the original function of hunting and taking down large prey (Driscoll et al. 2009). As wolves got closer in proximity to humans, the mutualistic relationship between the two species grew stronger. The humans were benefitting the wolves by providing them with food, and the presence of wolves began to deter other predators from coming in contact with human populations (Wang et al. 2013). Wolves also demonstrated a kind of alarm signal behavior for humans in the sense that they acted as “barking sentinels” warning humans of animal activity at night and when other animals were near that humans themselves could hunt (Driscoll et al. 2009). At this point, about 10,000 years after the beginning of the evolutionary divergence of dogs from wolves, the proto-dog was already very distinctly different from their wolf ancestors. Their behavior was tamer, which allowed humans to tolerate them living in such close proximity. Their body morphology had changed to be more specialized toward living and feeding near humans, and the extremely strict social hierarchy that existed in the ancestral wolves became more relaxed (Rodney 2010). The accumulation of genetic, phenotypic, and behavioral changes that occurred in wolves due to the indirectly exerted selective pressures from human had already made them semi-domesticated (Wayne 2012). This is why, as human society grew and the nomadic hunter-gatherers began to live more permanently in settlements, the proto-dog was by far the first and best choice of animal to be kept and utilized (Wayne 2012). This began with humans taking wolf pups from their mothers and raising them for the protection and assistance with hunting they provide (Wang et al. 2013). This is also where one of the two major genetic bottleneck events in the history of dogs occurred because humans began selecting dogs with only the traits they favored, reducing the diversity of the available gene pool (the other bottleneck was in the development of the different breeds) (Rodney 2010). Dogs were selected primarily on the basis of temperament and the ability to be trained, the dogs that had the characteristics humans wanted were raised and bred to pass on their genes. This was a bottleneck that reduced the genetic diversity of all dogs, and even though there are many phenotypically different breeds today, they have identical karyotypes and are about 93% genetically similar to one another (Wayne 2012). Now that humans were purposefully using artificial selection to breed dogs, several traits that were not directly selected for still became prevalent. Of the dogs with proper temperament and trainability, there was another subset of dogs whose behavior and interaction with humans made them even more likely to be bred onwards (Larson et al. 2012). These dogs, on an ontogenetic developmental level, had evolved much higher social-cognitive skills with humans; they, uniquely for any organism in general, were able to incorporate humans into their social hierarchal system as the new “alpha” or dominant member of society (Riedel et al. 2008). This led to a much greater degree of obedience, and the ability to process emotional signals from humans, including an understanding of subtle communicative cues such as the importance of what a human is looking at (something even most primates are not capable of). This is in part why dogs are considered to have coevolved with humans, their resulting behavior having been adapted specifically for living cooperatively with humans (Riedel et al. 2008). As humans dispersed across Europe, Asia, and Africa, so did the dogs they had with them. Dogs became an essential tool for human civilization and in different environments, the need for more specialized dogs became evident (Vilà et al. 1997). This brought on the advent of selective breeding, and the many resulting dog breeds that phenotypically vary immensely in size, shape, intelligence, and work utility (Vilà et al. 1997). Regardless of the amount of variation found between the breeds, the methods used by humans to create them were the same; dogs with desired characteristics, such as speed, were bred only with other fast dogs (Riedel et al. 2008). Over time, and after many repeated breedings, the breeds were formed. Interestingly enough, and despite the enormous amount of phenotypic variation between the breeds, they all belong to the same species: Canis lupus familiaris, this is reflected the how genetically similar all dogs are to one another (Wang et al. 2013). Today, the number of dog breeds has exploded in number to over 300 distinctly recognized breeds (Driscoll et al. 2009). Dogs continue their legacy of being highly coevolved with humans by making up for abilities humans lack and having many specific adaptations and traits that allow the two species to live symbiotically. Dogs are capable of living wherever humans do and fulfill many roles including those of protection, hunting, sensing, transportation, and companionship (Wayne 2012). It is not surprising that many people today keep dogs as pets, after all, it is a relationship that has been in the making for tens of thousands of years.