The following was a term paper written for my conservation biology class in collaboration with Hallie Draegert
It is a well-known fact that the human population is increasing in size. The growth of one population, the humans, tends to impact other populations negativity. In this case, the concern is the impact it has on wildlife populations. As long as wildlife and human populations coexist problems will arise. These problems can occur in response to tension between local human communities and the attempts of organizations working to conserve native populations of animals. Often these organizations seem to forget that the local’s livelihoods depend on exploiting the local animals. This has led to the creation of conservation models that do not work because they did not consider the local politics.
One of the most common crimes committed is poaching. Poaching has led directly to the extinction of many species and induces stress, on currently stable species. This could make future extinction of the population an issue that needs to be addressed. Since poaching is a serious problem for highly stressed species, it is critical to work to prevent the crime. There are many current techniques used to reduce and combat poaching. However, the issue has not been fully resolved. This is likely because only a single model is in use at a time in an area.
There are many dynamic relationships in the rainforests of the world. Which is expected as they are home to up to 40 percent of known plant and animal species. Within the forest there are a widely variety of symbiotic relationships, which means there are interactions between two species. For some species the relationship is beneficial for both parties, this is call mutualism. For example the Brazil nut trees (Bertholletia excelsa) produces a nut that is an only be cracked by a few species, one of which is various agouti (Dasyprocta sp.) which is a small rat like animal. The tree benefits as it’s seeds are dispersed and the agouti receives a free meal.
English: A Central American Agouti (Dasyprocta punctata) in Panama experimenting with a western diet.
In some cases one species is unaffected and the other benefits, this is commensalism. A example of this would be a frog sheltering itself from a storm event under the leaves of a plant. The plant is un effected but the frog benefits. Lastly, parasitism is when one species is harmed and the other benefits. Bot flies are a common tropical parasite that lay their eggs on a mammal host. The eggs then hatch and the larva develop in the skin of the host animal.
A frog in the rain in Belize. Image by Lauren Schramm
Competition is a symbiotic relationship in while two species use the same resources. Because it requires an energy investment both species are harmed, but the harm may be unequal. Many rainforest plants are animal pollinated or their seeds are dispersed by animals. Resource partitioning occurs when a resource is divided among species in some way like time or place. One way plants reduce their competition against each other is by targeting different animal groups. For example flowers pollinated by bats are often white making them easier to see at night, while flower pollinated by other animals are red, orange, and yellow. Bat pollinated flowers also contain a musky smells, while flower pollinated by moths, bees, and other insects have a strong fragrance. Plants also reduce competition by flowering and fruiting at different times. This is one reason there are always flowers and fruits available in the rainforest at any given time.
I used to teach a genetics lab and thought I would share what I taught my students. Before running polymerase chain reactions (or PCR), to make copies of your sample DNA, it is important to run a gel with your DNA extraction to see if the extraction worked. To run a gel, the DNA sample is loaded into wells on one side of a gel. An electrical current is used to separate out the DNA to analyze it. If your DNA extraction did not work it is a waste of money to run PCR on the sample. This gel is run in buffer TBE. TBE contains tris which raises the pH to 9, a boric acid which lowers the pH to optimizes it for the target enzymes, and EDTA which chelates metal ions and those stops DNeasy activity, which is the enzyme used for DNA extraction. The molecules in the gel separate based on charge, size, and shape. Personally, I like to use 1% agarose gel with TBE at 120 volts for 30 minutes.
But what is agarose? It’s a seaweed polysaccharide that allows the gel to thicken. The more agarose you use the thicker the gel and the longer it will take your DNA sample to run through the gel. If you need to separate out really small fragments you would need a really thick gel but since we are looking to see how well the DNA extraction worked we can use a thin gel. You should also stain the DNA sample before putting the sample in the gel. If you don’t stain the sample you wouldn’t be able to see where your sample goes in the gel and run the risk if running your sample off of the gel. Gels also often have glyercide in them that binds to the DNA and makes it heavier so when you load your DNA into the well on the gel it is less likely that the DNA floats away. It another well a ladder is also typically used. In this case, we used a 1000 kb base pair ladder. A ladder is DNA fragments that are cut at known lengths. This allows it to act as a ruler for your other samples.
Viruses are infectious particles made of nucleic acid encased in a protective protein coat and, sometimes, a membranous envelope. The genome of viruses may consist of double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA, depending on the kind of virus. The viral genome is usually organized as a single linear or circular molecule of nucleic acid. The genome is encased in a protein shell called a capsid which is derived from the host cell. The most complex capsids are found in viruses that infect bacteria, called bacteriophages or phages. A virus has a genome but can reproduce only within a host cell. Dr. Beijerinck used the sap from one generation of infected plants to infect the second generation of plants that could, in turn, infect future generations. Dr. Beijerinck determined that the pathogen could reproduce only in the host, could not be cultivated on nutrient media, and was not killed by alcohol which generally kills bacteria.
An isolated virus is unable to reproduce—or do anything else, except infect an appropriate host. This is because viruses lack the enzymes for metabolism and the ribosomes for protein synthesis. Each type of virus can infect and parasitize only a limited range of host cells, called its host range. Viruses identify host cells by a “lock and key” fit between proteins on the outside of the virus and specific receptor molecules on the host’s surface. Most viruses of eukaryotes attack specific tissues. Most DNA viruses use the DNA polymerases of the host cell to synthesize new genomes along the templates provided by the viral DNA.
In the cell cycle, cell division functions in reproduction, growth, and repair. The two forms of cell division are mitosis and meiosis. Mitosis requires the distribution of identical DNA to two daughter cells. Meiosis yields four nonidentical daughter cells, each with half the chromosomes of the parent. The purpose of meiosis is to produce cells for reproduction, and as you want the offspring to have the same number of chromosomes as the parents’ sex cells need to have half the number of chromosomes as the parents. A cell duplicates its DNA, moves the two copies to opposite ends of the cell, and then divides into two cells. This genetic information that makes up the cell’s genetic information is called its genome.
The genome is made up chromosomes. Every eukaryotic species has a characteristic number of chromosomes (packaged DNA) in each cell nucleus. Eukaryotic chromosomes are made of chromatin which is a complex of DNA and protein. When a cell is not dividing chromosomes are chromatin fiber in the nucleus. Each duplicated chromosome consists of two sister chromatids, which appear when cell divisions are about to take place. The chromatids are attached at what is called the centromere. After the chromatids divide mitosis is followed by division of the cytoplasm or cytokinesis.
R-selected and K-selected species are terms that biologist use to describe the reproductive strategy of animals. Either an animal produces a large number of offspring and it basically is a numbers game for those offspring or the animals have few offspring and invest a large amount of time in those offspring. R-selected species are those that favor a large number of offspring. This includes animals like insects, amphibians, many fish, and reptiles. They tend to be smaller organisms so the energy used to make each individual is low and live in environments that are unstable. They also have shorter lifespans and reach sexual maturity quickly. They have type III survivorship pattern which means that earlier in life more organisms will die than later on in their life. In these species, the number of offspring is important because it directly impacts the population size.