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In my neuroscience class we read a study about vision and its connection to the brain. The objective for this study is to understand the mechanism of non-visual reflexes such as regulation of the circadian clock and pupillary reflexes. The suprachiasmatic nucleus (SCN) is a site for photoentrainment in the brain. A portion of light-sensitive retinal ganglion cells protrude into the SCN. The authors hypothesized that melanopsin is a photopigment on the retinal ganglion cells (RPG’s) that generate action potentials to the brain in response to light, and play a role in photoentrainment. Although it was known that some RPG’s are photosensitive, the reasons for this phenomenon were unknown. It was also known that rods and cones are not photoentraining receptors. Provided this context, the reason for the study was to understand the function of RPG photosensitivity, and to use them to study the pathway that gives rise to photoentrainment.

In such a short segment of time, now 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss, introduction of exotic species, and global warming. Our time may only appear as a small slither of time at the moment, but this is exactly why it is so disturbing; especially since this is the first mass extinction to be caused alone by one species and create such a detrimental effect. Humans have literally “chewed a hole in the ozone layer over Antarctica, doubled the amount of methane in the atmosphere and driven up carbon dioxide concentrations by 30%, to a level not seen in 400,000 years”  (Anthropocene, Monastersky, 2015). As a species now, we have no bounds to where we can travel and spread across the earth, as well as we have the ability to alter environments and ecosystems purely to suit our needs. A species that very recently reached extinction is the Pinta Island Tortoise. La Pinta Island was being visited frequently by passing whalers as it was a spot for giant tortoises. Once it was discovered that these creatures could go long periods of time without food or water and their meat was delicious, the tortoises did not stand a chance. The population was slaughtered by the hundreds, throw aboard ships of explorers as well as whalers as a popular food source. For many years it was thought this was the end of these giant tortoises. However in 1971, one last member named Lonesome George was found roaming the island. Shortly after George was taken into captivity up until 2012, when his death marked the tragic end of the La Pinta line of tortoises.

Transpiration is the process by which moisture is carried through plants. Water is carried from the roots to small pores (stomata), where it changes to vapor and is released to the atmosphere. In simpler terms, it is the process by which water evaporates from plant leaves. Transpiration is a regulated process and it offers insight into how much water is needed for an individual plant to survive. Transpiration can be calculated by multiplying the conductance by the force. Conductance is 1/resistance, where resistance is the sum of resistance from the stomata and boundary layer. The force, represented by deltaC/deltaX is the change in the concentration gradient. Factors such as wind can impact the boundary layer resistance and will make the transpiration rate increase.

    To what degree is music theory necessary for modern music? Nowadays, there is a multitude of artists who have a very basic and crude understanding of music theory, and yet are able to succeed with the lack of it. This hasn’t been a modern phenomena either. There are some musical icons who are considered legends (like John Lennon) who were unable to read notation (something very basic) until very far into their careers as musicians. Currently there are artists out there who bleed music theory like Jacob Collier, who likes to play around with the boundaries of current theory to create new sounds and new music. A lot of Jacob’s music for example, plays around with polyrhythmic patterns like septuplets layered on quintuplets, with a melody following cut time (4/4). Yet when we look at modern day pop songs in comparison, for the most part they follow a simple 4 chord progression layers with electronic drum kits layered to form a beat. Some of it is a bit more complex with bass lines, vocal layering, and harmonics, but some of the best songs are really simple. The song “suede” by Anderson Paak for example, is a two chord progression throughout the song, yet was one of his most popular songs amongst the entire album.

The genetics of dog hair colour is much more complicated than most people might think. There are many different genes, each themselves with sometimes three or four alleles, whose combination leads to the hundreds if not thousands of different coat varieties seen in canids both domestic and wild. Many people tend to think of genetics as working in the traditional Mendelian fashion of basic dominance and recessiveness of genes but dog hair colour is one of just many examples where the answer is not that simple. The introduction of more than two alleles whose dominance over one another varies leads to many more possible combinations of traits and is why the pattern, colour, length and curliness of dog hair varies so widely across the family Canidae. 

Although other factors influence tree growth, the amount of light receive by a tree has a large effect on growth. Because the amount of sunlight can be limiting to tree growth, the different slopes should have some effect on tree growth on mountains. It is known that the south facing slope in the northern hemisphere receives more direct sunlight due to the Earth’s tilted axis. If sunlight is the only direct factor that determines tree growth, trees on a southern slope of a mountain should grow larger than trees on the northern slope. Sunlight, however, is not the only factor that determines tree growth. Nutrients and water availablity have a significant impact. Plant require abundant amounts of phosphorus and nitrogen. These nutrients are not always readily available in soil. These nutrients come in different forms. Trees can only take up a couple of these different forms. Therefore, bacteria can be necessary to convert the bacteria to useable forms. 

Culture, even in non-human species such as chimpanzees, can be defined as the alteration over time of learned behaviors. One such learned behavior is the chimpanzee’s hoot. The hoot is a call made by chimps in order to identify one another. This identification is possible because of the fact that this behavior is learned, meaning it can differ from population to population. In other words, one troop of chimps will have a different hoot than another troop. As it turns out, chimpanzees are both very aggressive and very territory when it comes to chimps outside of their troop. Because of this, they will often engage in wars between troops. These wars are possible because one population can locate another via the unfamiliar sound of their hoot. Scientists have been able to confirm this through the cultivation of artificial chimpanzee troops in enclosed sanctuaries. Injured or orphaned chimps rescued from labs or the wild will start with their own unique, learned hoot before being assimilated into the sanctuary. Once successfully assimilated, the chimps will converge on one identical hoot that they may use to communicate with one another. This convergence is a perfect example of culture within a non-human species.

Mammalian teeth come in many different forms and differ from the teeth of reptiles in that mammals have evolved heterodonty which is the condition of having specialised teeth for different functions. Reptiles have uniform teeth that do not differ in form or function, the condition known as homodonty. Mammalian teeth fall into four different categories, each with different form and function. At the front of the mouth are incisors, behind which is a pair of canines which may or may not be present, followed by premolars and molars. Apart from canine teeth of which there is always only one or none on each side, the number of each tooth type varies by species. Us humans have in total (usually) 32 teeth, of which eight are incisors, four are canines, and eight premolars and molars. 

Herring gulls and Black-backed gulls are two separate species of seagull that live side by side, exhibiting a wide variety of identical behaviors that allow them to communicate during significant times in their lives. These gulls breed in close quarters on coastal islands in the North Atlantic. Because of the proximity to one another, these seagulls have had to develop intricate ways of communicating with one another in order to successfully court mates, breed, nurture young, and survive. It is important to understand that animals send signals with the understanding that they will receive a response. There are three main categories of gull signaling behaviors: territoriality/aggression, parental care, and courtship. When it is a question of territoriality, gulls will always prefer to signal before engaging in aggression. One such signal is known as upright posture, which is an extension of the gull’s back and the slight spread of its wings. Upright posture is a threat display used by gulls to maintain or negotiate territory in their close-knit colonies. This display is used most often right after chicks hatch, in an effort to solidify their territory to protect their young. However, before chicks can hatch, gulls must court mates. To begin courtship, females will fly around the colony and assess the fitness of males from the air. When they find a suitable male, they will land in his territory and immediately assume one very important behavior: begging. The begging behavior is learned as a chick to ask their parents for food, but females use it during courtship to gain the trust of the unfamiliar male. This behavior is characterized by an outstretching of the neck upwards, directly into the face of the male. During this time, the female is literally asking the male for food. If the male complies and gives the female food, their pairing begins. Once gulls are paired, they establish their territory, establish a nest, and begin copulation. Copulation begins by using the same behavior that the chicks and the female once used; the begging behavior. The female gull will exhibit this begging behavior until the male agrees to copulate. The male will then stand on the back of the female and begin mating. The mating ritual is an interesting one because the male gull will use a behavior only seen during this time. Once mating has begun, the male will elicit what is known as a mating call; a unique sound that can only be heard during the mating season. The upright posture, begging, and mating call are among many important behaviors that these gulls must use to communicate, care for their young, and stay alive.