asalamon's blog

1. While on campus at UMass Amherst, enter the Campus Center through the east entrance.
2. Roughly 10 meters forward on the right is Harvest Market
3. The perspective photograph of phytophagy was taken in landscape view with the "Harvest" sign framing the top of the photograph and the sides of the store outlining the left and right side borders
4. Enter Harvest Market and proceed straight forward to the salad bar.  
5. Remain on the south side of the salad bar
6. Take another photograph focused on the left side of the salad bar with the three types of lettuce for selection in the frame
7.  

Figure 1. Drosera rotundifolia.  Drosera rotundifolia has tendril-like extensions which collect dew. "Drosera rotundifolia." flickr photo by Free the Image https://flickr.com/photos/freetheimage/14129398634 shared under a Creative Commons (BY) license

Figure 2. Water Properties.  Surface tension is one of the properties of water as seen on the Drosera rotundifolia which keeps the water in spheres on the tips of the red tendrils. "Drosera rotundifolia." flickr photo by Free the Image https://flickr.com/photos/freetheimage/14129398634 shared under a Creative Commons (BY) license

Bilirubin is a by-product of red blood cell breakdown which is a mammilian specific by-product of red blood cell breakdown.  Reptiles, amphibians, and birds all have red blood cells break down in heme then to biliverdin, something they are able to excrete without any addtional breadown.  Mammals, on the other hand, have the bilirubin break down into biliruben. One of the key evoltionaly differences between mammals and these other species is the placenta connecting the mother and child together.  Since this trait has evolved and been conserved through mammels, it begs the question if there is a benifit to having biliruben in the system of infants.  Biliruben is an antioxident that could prevent DNA damage during the development fo the fetus.  

In utero, the fetus’s red blood cells break down and is filtered through the placenta.  From there, the mother breaks down the bilirubin into the expendable form in their liver and its rid of waste.  When a baby is born, it is disconnected from the mother and its liver is not fully functional so it cannot breakdown the bilirubin themselves.  If levels of bilirubin are too high, the baby can be diagnosed with hyperbilirubin which appears are jaundice in the baby.  This is concerning to doctors taking care of the newborns becuase if the levels of biliruben are too high, then the child would be left with serious brain damage.  Depending on how much jaundice the newborn is presenting, they are placed under lights to reduce the levels of biliruben.  If the levels of biliruben in newborns did not benefit the fitness of the child, then natural section should have weeded it out.

Why are humans, as a species vunderable to osteoporosis? Why are women even more susceptable to the illness?  These questions can be answered through evolutionary medicine.  Bones begin as cartilage with centers of ossification that allow for the growth of the bone over time.  Eventually, the centers for ossificaiton fuse and the bone stops growing.  Besides infancy, the fastest time for growth occures during adolesence.  The growth rate is direclty related to the amount of IGF released by the pititary gland of the individual.  During pubery for females, the bone density is rapidly being packed onto the bones.  Once puberty ends, females have a significalty higher bone density and mass than males.  This is important for reproduction as the calcium and nutrients of the bones is essential to pregancy and breastfeeding.  During menopause, women have a serious decrease in the amount of estrogen they produce. As a result there is a sudden drop in bone density.  As opposed to men who see a steady decrease in bone density over time, women see a sudden drop in bone density then continue to deterioate at a steady rate from there.  Because of the sudden drop during menopause, women are at a greater risk for osteoporosis than men.  This is an example of antagonistic pleiotrophy.  While levels of estrogen in women during puberty are essential to successful reproduce, they result in deterious consequences later in life.  

Mendel, one of the founding fathers of genetics, was well known for his empirical approach to genetics.  Through his studies of pea plants, he was able to discover that specific morphological characteristics had variable traits from plant to plant.  These traits were able to be passed down from the parents into the next generation of pea plants.  Among these traits, some of them are dominant while other are recessive.  Through self fertilizing the pea plants, Mendel was able to identify true breeding plants.  These plants are known as homozygous now.  When two true breading plants were crossed, they produced plants which contained both variables of the trait.

For breast feeding mammals, only the infants and the young are able to breakdown lactose.  Once they reach an age of maturity, the gene which produces lactase, the enzyme which breaks down lactose, is turned off.  Since lactose cannot be broken down into simpler sugars, it reeks havoc on the small intestine.  Perhaps, this the gene turning off was to keep the breast milk only going to the infants of the population and not to the older individuals which have more food choices available to them.  Although not everyone can break down lactose, there are certain human populations which have this ability.  These populations are those who domesticated animals and use their milk as a key part of their diet.  Through the four forces of evolution, the ability to digest lactose in adulthood has persisted around the world.  It only takes a single point mutation to turn on the gene which produces lactase.  There is no way of telling if this mutation occurred once in history but it likely that convergent evolution was at play.  Next, gene flow or the interbreeding of humans continued to spread the gene.  Natural selection also increase the prevalence of this gene in population that domesticated animals.  Finally, the founder’s effect, a type of genetic drift, would have spread this ability to new colonizations with a high probability of the members having the mutation.

Bilirubin is a by-product of red blood cell breakdown.  When red blood cells break down, bilirubin is in the unconjugated form.  Bilirubin can only be removed from the body in its conjugated from which requires its breakdown by the liver.  In utero, the fetus’s red blood cells break down and is filtered through the placenta.  From there, the mother breaks down the bilirubin into the expendable form in their liver and its rid of waste.  When a baby is born, it is disconnected from the mother and its liver is not fully functional so it cannot breakdown the bilirubin themselves.  If levels of bilirubin are too high, the baby can be diagnosed with hyperbilirubin which appears are jaundice in the baby.  Babies exhibiting too much jaundice are placed under lights.  Why is hyperbilirubin so prevalent in babies? Bilirubin is antioxidant and could help prevent any damage that could occur to the DNA during fetal development.  This condition is prevalent in other species closely connected to humans as well.  If it did not benefit the fitness of the child, then natural section should have weeded it out.

One longstanding debate in the field of biology is whether or not viruses should be considered living organisms.  Viruses are composed of a protien coat with genetic material contained on the inside.  The genetic material can vary from segments of RNA to DNA depending on the type of virus. Unlike all other species not debated as "living," viruses lack the ability to reproduce on their own because of their design.  Instead, viruses are only able to reproduce or replicate within a host.  By using the machinery present in their host cells, they are able replicate and spread the virus.  For those who believe viruses are not alive, this is one of the main points they cite: without a host cell, virsuses would not be able to survive therefore should not be considered alive.  The opposition believes viruses should be considered alive because of the success they have at infultrating their hosts and reproducing.  Like all other species considered to be living, success by a virus should be determined by their reproductive fitness.  Those who are not fit are removed from the population while those fit to survive pass on their ability to the next generation.  The niche that viruses find themselves in the ecosystem is one that they have remained in since long before their discovery.  Yes, viruses need a host but a host is their niche.  If they were not fit for this niche, they would not survive or exist in the living world but they do.

In Darwin's Theory of natural selection, there are three conditions that must be met for natural selection to occur.  First, there must be variation of the trait within the population.  Second, the trait must be hertiable therefore passed down to the offspring.  Finally, there must be an increase in reproductive sucess connected to having this trait.  One example of natural selection is the prevelence of lactose tolerance in humans.  First, there is variation in the trait because some humans are able to drink a glass of milk without any digestive complications while others are not.  Second, those who are able to drink milk are able to pass down this trait to their offspring.  Finally, having this trait leads to a greater reproductive sucess because there is access to a new food source and other dietary benefits.  As a result, there is a 5% fitness incease among the population who is able to digest lactose.  This adaptation has occured several times in populations from east Africa to Europe to the Middle East and India.  The sucess of the adaptation can also be seen in the gene flow that passes this trait around the world.