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https://en.wikipedia.org/wiki/Sexual_dimorphism - one sentence and 1 citation

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Final Draft starts here. Birds come in many colors and patterns and dramatic displays, these unique colors are an important adaptation that has developed throughout evolution. The reasons why birds have such brightly colored and patterned feathers can be discussed in many different ways from an evolutionary standpoint, including but not limited to sexual dimorphism, adaptation and sexual selection. The focus of this paper will be why this unique dichromatic display has been such an important factor throughout evolution for different avian species. Sexual dimorphism is the one mechanism that is most frequently associated with why birds, males in particular, have evolved with such elaborate colors and unique patterns in their plumage. Since majority of the male birds are the ones who have developed such amazing display of feathers. It is easy to come to the conclusion that evolution has selected for these bright and elaborate displays of colors and ornamental quills because they are beneficial to some part of the males life, perhaps their coloring is a way to attract mates, or scare off predators, or blend in with their surroundings. A common theory regarding sexual dimorphism in birds is that males with the brightest colored plume will get a mate easier because the bright colors will show the female that he is healthy, and will therefore produce healthy offspring. New studies are providing new information that links the bright plumage to sexual dimorphism in birds. These bright colors that males display could have been developed in two ways. The first is that alleles for the dimorphic traits were by and large selected for in males and the second is that the dimorphic traits were initially expressed in both sexes and then selected for in males (Coyne and Kay and Pruett-Jones 2008). This could explain why in some species, females still display the same colors and patterns as the males. It could have been useful in those species for the female to keep the bright plumage.

Like sexual dimorphism, sexual selection in particular intersexual and intrasexual selection can explain why males display such feathers and why females show interest in what the male looks like. Intersexual selection gives the female an opportunity to choose between males for the best mate. Having the ability to chose your mate, means that you not only get the chance to produce viable offspring but also can lead to having to do less work such as building your own nest or raising the offspring. On the other hand intrasexual selection which is commonly seen between males is an important evolutionary component because the males will compete for the female’s attention due to the fact that males’ reproductive success is controlled by the female’s egg production because it is so costly to lay eggs; so if you’re a male and you have more vibrant quills than you have a better opportunity to be successful in the end. Newer studies are showing that the color of plumage can be linked to other aspects of avian behavior, such as the height at which different species build their nests. While some male birds will often build or aid in building the nest, they don’t always stick around to raise the young. So nest height not only is linked to male birds but more importantly linked to female birds. Since the females do most of the rearing of the young it is important for the female to be located in a safe nesting environment, part of that is having a display of duller colored down so that she may blend into her nesting environment. Since females are usually the prime care taker for the young the height of the nest is an important reason why they often display much duller colored feathers compared to the males. The position of the nest and whether it has a greater chance of being under predation has exerted constraints onto female bird’s plumage (Martin and Badyaev 1996). A species of bird that makes it nest on the ground, opposed to the canopy of the trees, will need to have much duller colors in order not to attract attention to the nest. Since the female is the main care giver in some species of birds, evolution has helped select traits that make her feathers dull and often allow her to blend into the surroundings. The height study found that birds that nest in the canopies of trees often have many more predator attacks due to the brighter color of feathers that the female displays (Martin and Badyaev 1996). Since females invest so much energy to reproduce it has paid off to lose bright colors in order to keep your offspring alive depending on where that species builds their nests. When it comes to bright feather display in males things will tend to change in the way birds mate or raise their young. Many birds’ species are monogamous and mate for life. However sexual selection tends to show that females are attracted to males with the brightest feathers, and these males do not always make the best fathers, in terms of providing paternal care. Males with brightly colored feathers often never provide parental care or help with other paternal needs (Dunn,Whittingham, Pitcher 2001). This leads to an interesting phenomenon called extrapair paternity, where the female will mate with a male that displays more vibrant colors but makes a bad partner, and then she will raise those young with a partner who might not have the best coloring but makes a better parent. The female is successful in this situation because she gets to improve the genetics of her offspring while still getting a mate that will help her raise another male’s young (Moller and Birkhead 1994). While sexual selection supports why birds, especially males, developed bright colors and unique patterns, there are studies that suggest other reasons besides sexual selection that may have lead to birds to developing bright plumage. For example, a study by Stoddard and Prom suggests that birds developed their bright colors from the vegetation and flowers that thrive around them. Birds develop their bright colors from living around certain colors. Most bird species often blend into their environment, due to some degree of camouflage, so if the species habitat is full of colors and patterns, the species would eventually evolve to blend in to avoid being eaten. Bird’s feathers show a large range of colors, even exceeding the variety of many plants, leaf and flower colors. Colors in birds are not distributed evenly; instead they differ by large hue ranges (Stoddard and Prom 2011). Maybe this is evidence to why birds in tropical regions are some of the most vibrant compared to birds in North America where the species of birds do not always display bright colors. It could be that these parts of the world are always full of bright colored leaves and flowers and the species that live in these areas need to keep their bright colors in order to blend in all year round. While lots of species of birds display bright colors not all bird species are as flashy as others. Some species of birds, owls, hawks and falcons for example are not in need of bright colors but instead benefit from having dull colors and patterns. While bright colors are very useful in getting a mate for some, other species do not need to rely on bright colors but instead need to be camouflaged in order to eat to survive. Birds of prey have evolved over the years to depend on designs instead of color as a way to survive. Since these species of birds are built for hunting they have developed a unique bared and spots patterned quills that aid in their ability to be stealth hunters. While these unique patterns are sexually selected for demonstrating that some sexually selected traits can be cryptic (Gluckman and Cardoso 2010). Having camouflaged feathers is an advantage to species of birds that need to blend in to survive and avoid predators. Another advantage to having patterns is that patterns on the feathers may provide opportunities for signaling health to a mate, opposed to having bright colors for the signal (Bortolotti, Blas, Negro, Tella 2006). Birds that could produce noticeable patterns would be having a higher fitness level and be considered the better mate, especially with birds of prey where both parents usually contribute to raising the young. Another advantage that birds with motifs have over birds of bright colors is that they can display some behavioral modifications that colorful birds cannot. While having color can be a good thing it can also never be hidden, while birds with patterns can manipulate their pattern through rearrangement of their feathers (Bortolotti, Blas, Negro, Tella 2006).Patterned feathers can be used as a way to signal danger or food to other members of their community, which means they can communicate without sound. Some studies link the pattern on the feathers to the size of the bird. So a certain species of bird that contains barred may have a certain size always linked to it. Feathers that contain streaks are associated with small, compact species, while bars are associated with more large-bodied species (Riegner 2008). Having a certain size and displaying a certain type of motif would be an advantage to your environment. Birds that are smaller need to be able to blend in, so having selected certain design so that you fit into your environment better would be an advantage. While a bird that is a larger size would want to blend in to but for opposite reasons they want to blend in order to be able to catch prey. Whether you’re a male peacock with an elaborate train or a common house sparrow, birds of all species have selected traits throughout evolution to ensure that their species carries on. These adaptations that they have developed over the years are a way for these species to come out on top. There are always new studies being conducted to explain why birds have the ability to display so many colors and designs; and what the use they have for them. While sexual dimorphism is a very big driving force for why being bright in color would equal higher fitness and make you a better mate, it is not the only evolutionary component. The research is endless, just like the color and patterns that birds can display. As long as birds are continuing to develop amazing colors and motifs, the evolution research will continue on.

References Bortolotti, Gary R., Blas, Julio, Negro, Juan J., Tella, Jose L. 2006. A complex plumage pattern as an honest social signal. Animal Behavior, Volume 72 issue 2: 424-430. Coyne, Jerry A. and Kay, Emily H. and Pruett-Jones, Stephen. 2008. The genetic basis of sexual dimorphism in birds. Evolution volume 62, no.1: 214-219. Dunn, Peter O. and Whittingham, Linda A. and Pitcher, Trevor E. 2001. Mating systems, sperm competition, and the evolution of sexual dimorphism in birds. Evolution, vol. 55, no. 1: 161-175. Gluckman, T-L. and Cardoso, G.C. 2010. The dual function of barred plumage in birds: camouflage and communication. Journal of Evolutionary Biology, vol. 23, no. 11: 2501- 2506. Martin, T.E. and Badyaev, A.V. 1996. Sexual dichromatic in birds; importance of nest predation and nest location for females versus males. Evolution vol. 50: 2454-2460. Moller, A.P. and T.R. Birkhead, 1994. The evolution of plumage brightness in birds is related to extrapair paternity. Evolution vol. 48: 1089-1100. Riegner, Mark F. 2008. Parallel evolution of plumage pattern and coloration in birds: implications for defining avian morph space. The Condor, vol. 110, no. 4: 599-614. Stoddard, Mary Caswell and Prom, Richard O. 2011. How colorful are birds? Evolution of the avian plumage color gamut. Behavioral Ecology, vol. 22, issue 5: 1042-1052.

Edit of a page https://en.wikipedia.org/w/index.php?title=Feather&action=edit While sexual selection plays a major role in the development of feathers,in particular the color of the feathers it is not the only conclusion available. New studies are suggesting that the unique feathers of birds is also a big on many important aspects of avian behavior, such as the height at which a different species build their nests. Since females are the prime care giver, evolution has helped select females to display of duller colored down so that she may blend into her nesting environment.The position of the nest and whether it has a greater chance of being under predation has exerted constraints onto female bird’s plumage. A species of bird that makes it nest on the ground, opposed to the canopy of the trees, will need to have much duller colors in order not to attract attention to the nest. Since the female is the main care giver in some species of birds, evolution has helped select traits that make her feathers dull and often allow her to blend into the surroundings. The height study found that birds that nest in the canopies of trees often have many more predator attacks due to the brighter color of feathers that the female displays. Another influence of evolution that could play a part in why feathers of birds are so colorful and display so many patterns could be due to that birds developed their bright colors from the vegetation and flowers that thrive around them. Birds develop their bright colors from living around certain colors. Most bird species often blend into their environment, due to some degree of camouflage, so if the species habitat is full of colors and patterns, the species would eventually evolve to blend in to avoid being eaten. Bird’s feathers show a large range of colors, even exceeding the variety of many plants, leaf and flower colors.