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This is Lauren's sandbox

https://en.wikipedia.org/wiki/Nocturnality Text added to article: More specifically, these animals have been found to have a larger cornea relative to their eye size than diurnal creatures, in order to increase their visual sensitivity in the low light conditions.[2] Citation: Hall, M. I., Kamilar, J. M., & Kirk, E. C. (2012). Eye shape and the nocturnal bottleneck of mammals. Proceedings of the Royal Society B: Biological Sciences, 279(1749), 4962-4968. doi: 10.1098/rspb.2012.2258

Talk Sections added: 1. The Nocturnal Eye

The article mentions that a nocturnal animal hunts at night, and has the advantage over other animals that have poor vision in the dark. It fails to mention WHY these nocturnal animals have different eyes than the others. What makes them different? How are their eyes able to function so well in the dark while other animals eyes cannot? I think it would be worthwhile for a section to be added perhaps comparing and contrasting the nocturnal eye vs the diurnal eye so that this unique biological adaptation could be explained in an anatomical sense. Davis.3548 (talk) 01:52, 1 October 2014 (UTC)

2. Have there always been nocturnal animals?

It would be interesting to include a section addressing how these nocturnal animals came to be, perhaps with a few specific examples. Take a tiger for instance, has is always been active at night, or have certain pressures and evolutionary forces shaped its lifestyle to become that way? Also, how does the eye of a present day tiger compare to one 100 or so years ago? Bottom line is that it might be worth a look at how these animals arose, and what drove them to be nocturnal rather than diurnal (besides the predation explanation)Davis.3548 (talk) 02:07, 1 October 2014 (UTC)

3. Effects of Predation

The article mentions that one of the reasons a lion may hunt at night is because its prey, like zebras, have poor night vision. I am curious to see if these zebras are beginning to become better equipped to see at night, in order to avoid this predation by the lion. Natural selection would favor those zebras able to allude the lions, perhaps because they have better eyesight, although other reasons may be responsible as well. This may also be able to tell us more about the evolution of nocturnality.Davis.3548 (talk) 02:23, 1 October 2014 (UTC)

FINAL PAPER STARTS HERE

Evolution of the Eyes in Nocturnal and Diurnal Organisms The eye is an intriguing area of exploration in evolutionary biology. While it has the common function of sight across the majority of species, the process of how it enables the organism to see, and when it enables them to see best differs based on the environment in which they live. The study of the divergence of the diurnal and nocturnal eye offers insight to how evolution has worked to increase an organism’s fitness depending on their habitat and niche. This information can then be used to examine different observations in nature, such as predator-prey relationships. Evidence shows that visual systems have evolved frequently in a short period of evolutionary time, suggesting that it is a more complex process than what was once thought. In the context of this research, diurnality refers to organisms that spend the majority of their time active during the day, and complete activities such as hunting, caring for young and interacting with each other during this time. An obvious example of this is humans, active by day and sleeping at night. Nocturnality is displayed when an organism is active at night, and sleeps during the day, like a bat or jaguar. Specialization in any one area always requires a deficit in another. This is what is known as a tradeoff. We see this in evolution quite often, and when we do see one, we know that whatever is being specialized in must be extremely advantageous to the organism. Being nocturnal boosts visual sensitivity but causes loss of resolving power, meaning the sharpness of images. Being diurnal heightens visual acuity, while costing the individual the ability to see in poor lighting conditions (Schmitz 2010). The amount of light that is present and available to the organism is the most important selective power of the evolution of nocturnality and the visual system (Hall, Kamilar & Kirk,2012), and the organism cannot have both high acuity and high sensitivity. There are distinct morphological differences in the eye that causes each of the vision specializations. It includes both eye shape and eye composition. The nocturnal eye has a much larger pupil and cornea size relative to their eye size. This is what causes their increase in visual sensitivity. The larger pupil causes a smaller focal length, so even the slightest amount of defocus causes a substantial amount of blurriness for the organism, causing their decrease in visual acuteness. Furthermore, rods are responsible for low light vision, so it makes sense that the eyes of nocturnal animals contain a greater concentration of these. Cones are responsible for color vision, are what respond to bright light conditions (Malmstrom, 2006). There are more of these in diurnal organisms. So what is it that determines which of these benefits the organism more? It depends on their behavior and environment, and what best suits their needs at that time. For example, a study conducted on over fifteen different communities of primates from various areas across the globe revealed the presence of both nocturnal and diurnal communities (Ankel-Simons & Rasmussen, 2008). This supports the idea that the eye is quickly able to adapt and change to the circadian configurations in order to fill whatever available role there is to fill in their environment. A closer look at these organisms eyes show that the nocturnal eyes contained a greater concentration of rods than diurnal organisms. They also have fewer cones, and thus less color vision, another example of an ecological tradeoff. The study also revealed that these differences in eyes of such closely related species occurred rapidly and frequently. These quick transitions occurred in a very short evolutionary time, suggesting the strength of the environment on the eye adaptation (Ankel-Simons & Rasmussen, 2008). One of the major questions circulating this topic is which came first, nocturnal eye or diurnal eyes? There is one leading hypothesis that has been gaining more support with recent research. Known as the “nocturnal bottleneck” theory, it suggests that the ancestors of most modern day organisms became nocturnal in the Mesozoic era in order to avoid falling prey to the many diurnal predators. They evolved nocturnal features, along with a heightened olfactory system to account for their poorer vision. The theory postulates that due to relaxed selection, these early organisms lost adaptations for diurnal vision. One of the most recent studies involving this theory took eye shape measurements from over two hundred species, and saw how closely the shapes predicted nocturnality (Hall, Kamilar & Kirk,2012). The results showed that lizards and birds correlated extremely well with the expected results, larger eye and cornea means the organism is nocturnal. However, the result that supports the bottleneck hypothesis is that mammals, which are now for the most part diurnal, had eye shapes that closely resembled nocturnal expectations. The only exception to this was anthropoids, which appeared to have the most divergence from nocturnality of all categories tested (Hall, Kamilar & Kirk,2012). So we then ask, why haven’t eyes in mammals evolved back to what is expected of diurnal creatures? The leading explanation is that the highly acute vision is no longer needed for survival, because organisms have evolved multiple other sensory systems to account for the diurnal adaptations lost thousands of years ago. The bottleneck suggests that the majority of mammals have maintained the design of a nocturnal eye as a result of their nocturnal origin (Heesy & Hall, 2010). Another example of evolutionary trade-offs and further support for the frequent fluctuation of the visual system can be seen in the genome. The opsin gene is a class of gene that regulates color vision. Due to the majority of their activity taking place in low light environments, nocturnal animals usually have a few of these genes that do not function properly, most likely due to “relaxed selection on the visual system.” A study was done on bats, examining their short and long wavelength opsin genes. While they found that the long wave genes were intact and functional, they found that the short wave genes were for the most part nonexistent. These findings suggest that the long wave opsin genes might play other roles in the visual system, but the short wave genes are no longer necessary due to the emergence of other sensory systems (Zhao et al 2009). In bats, this other sensory system would be echolocation and olfaction (Rydell, 1995). There is one interesting case study worth mentioning. There is one exception to trade off rule when it comes to vision, and that is birds. Physically, birds have extremely large eyes in relation to their body size, a characteristic of nocturnality discussed earlier. In a study analyzing the relationship between eye and brain size and prey capture techniques and nocturnality, a statistically significant correlation was found(Garamszegi, Moller, & Erritzoe, 2009). This finding suggests that brain size and visual systems in birds have coevolved in order to live their way of life. It has been discussed how nocturnal animals have worse vision but heightened other sensory systems, but with birds this is not the case. Their bigger eye size leads to a higher amount of photoreceptors, but not just rods for low light vision. Cones for visual acuity are included in this extra amount of receptors. These conclusions are supported in analyzing the behavior of these animals. They must be able to see and track their food while flying at a high velocity and/or at a high altitude, so both kinds of photoreceptors; those for low light vision and those for visual acuity, are extremely important and must be present in higher quantities. This is why birds do not have as heightened senses as other organisms. Through reviewing several studies, it can be concluded that the nocturnal effect on the eye is not as clear cut as was once thought. While some organisms exhibit characteristics that one would expect from a nocturnal animal, others show completely different patterns. There have been many relatively quick evolutionary transitions in visual system structure, suggesting that the visual system is highly adaptive, and highly influenced by the environment and niche of the organism. After analyzing diurnal versus nocturnal eyes, evolutionary tradeoffs are apparent, as organisms cannot have both visual acuity as in diurnal animals and visual sensitivity as in nocturnal animals. There is then the bottleneck theory, which says that long ago nocturnal organism had the highest rate of survival due to the numerous diurnal predators, and many organisms that are diurnal today retain some morphological characteristics of their nocturnal ancestors.

References 1.	Ankel-Simons, F., & Rasmussen, D. (2008). Diurnality, nocturnality, and the evolution of primate visual systems. American Journal of Physical Anthropology, 137(S47), 100-117. doi: 10.1002/ajpa.20957 2.	Garamszegi, L. Z., Moller, A. P., & Erritzoe, J. (2002). Coevolving avian eye size and brain size in relation to prey capture and nocturnality. Proceedings of the Royal Society B: Biological Sciences, 269(1494), 961-967. doi: 10.1098/rspb.2002.1967 3.	Hall, M. I., Kamilar, J. M., & Kirk, E. C. (2012). Eye shape and the nocturnal bottleneck of mammals. Proceedings of the Royal Society B: Biological Sciences, 279(1749), 4962-4968. doi: 10.1098/rspb.2012.2258 4.	Heesy, C. P., & Hall, M. I. (2010). The Nocturnal Bottleneck and the Evolution of Mammalian Vision. Brain, Behavior and Evolution, 75(3), 195-203. doi: 10.1159/000314278 5.	Malmstrom, T. (2006). Pupil shapes and lens optics in the eyes of terrestrial vertebrates. Journal of Experimental Biology, 209(1), 18-25. doi: 10.1242/jeb.01959 6.	Rydell, J. (1995). Evolution of nocturnality in bats: Potential competitors and predators during their early history. Biological Journal of the Linnean Society, 54(2), 183-191. doi: 10.1006/bijl.1995.0011 7.	Schmitz, L., & Motani, R. (2010). Morphological differences between the eyeballs of nocturnal and diurnal amniotes revisited from optical perspectives of visual environments. Vision Research, 50(10), 936-946. doi: 10.1016/j.visres.2010.03.009 8.	Zhao, H., Rossiter, S. J., Teeling, E. C., Li, C., Cotton, J. A., & Zhang, S. (2009). The evolution of color vision in nocturnal mammals. Proceedings of the National Academy of Sciences, 106(22), 8980-8985. doi: 10.1073/pnas.0813201106

EDITS MADE TO ARTICLE "Nocturnality" Origins While it is difficult to say which came first, nocturnality or diurnality, there is a leading hypothesis out in the evolutionary biology community. Known as the "bottleneck theory", it postulates that millions of years ago in the Mesozoic era, many ancestors of modern day mammals evolved nocturnal characteristics in order to avoid contact with the numerous diurnal predators. A recent study attempts to answer the question as to why so many modern day mammals retain these nocturnal characteristics even though they are not active at night. The leading answer is that the high visual acuity that comes with diurnal characteristics isn't needed anymore do to the evolution of compensatory sensory systems, such as a heightened sense of smell and more astute auditory systems. The anomaly this theory were anthropoids, who appeared to have the most divergence from nocturnality than all organisms examined. While most mammals didn't fall exhibit the morphological characteristics expected by a nocturnal creature, reptiles and birds fit in perfectly. A larger cornea and pupil correlated well with whether these two classes of organisms were nocturnal or not