In this lab, we simulated real-life natural selection patterns through an experiment involving picking up food (corks) in various ways based on three different phenotypes: stumpies (AA), knucklers (Aa), and pinchers (aa).
Lab overview and procedure
Knucklers and pinchers were the best at catching food, as knuckles or fingers were better for picking up food, and thus survived the most. The small a allele increasing significantly in frequency supported this, going from 50% of the gene pool to 0.74% of the gene pool in round 5.
In our experiment, our population evolved, as the allele frequencies shifted significantly due to differences in individual phenotypes. The frequencies of the large A and small a alleles went from 0.5 and 0.5 to 0.38 and 0.62 over the course of the experiment. In addition, at the end of the experiment, there were 14 knucklers, 6 pinchers, and 1 stumpy from the 10-10-10 makeup of the beginning; all of the data points to a gradual shift in the gene pool of the population.
Graph of allele frequency over time in experiment
Much of the changes in this experiment were due to non-random factors (e.g. natural selection). However, random events also impacted the experiment; genetic drift caused by changes in the food dispersion, as well as cheating to survive both affected the data. When the food was gathered in piles near some individuals, they were able to collect more food and thus survive and reproduce better. Additionally, some individuals resorted to cheating (i.e. grabbing technique) when selective pressures were high, and thus had an advantage unrelated to their traits.
In nature, when resources and conditions change, individuals and populations are affected: adaptations come into effect, and some individuals die out as a result of being unfit for the new conditions. For example, if an invasive species were to be introduced into the area, it might kill off or compete with the population, thus causing fewer individuals to survive. Similarly, the results of the lab may have been different if some key factors were changed. If the food was larger, the stumpies may have fared better, with an easier time picking up the food. On the other hand, if the food was smaller, it might benefit the pinchers, as they have an advantage picking up smaller food over the other phenotypes.
If there were not incomplete dominance, then there would be many more stumpies (making up 75% of the potential genotypes from a double heterozygous cross), as they are a result of the dominant big A allele. Conversely, without the knuckler phenotype, the pinchers would quickly outcompete the stumpies and dominate the population.
In this lab, we saw how natural selection is a major driving force of evolution, as it changes populations to make traits beneficial for survival more common over generations. Our beneficial allele was the small a allele, as pinchers and knucklers were better at surviving, so over time that allele became increasingly prevalent. Therefore, there were more pinchers and knucklers at the end.
Individuals adopted new techniques during the experiment. When selective pressures were high, they often cheated with a grabbing technique to increase their chances of survival. This likely led to there being more individuals with inferior phenotypes (i.e. more stumpies survived). Thus, it would have also increased the frequency of large A alleles. In nature, adaptations over time would play a similar role, beneficial mutations leading some to survive while others died off. An example would be the peppered moth: the black phenotype let the moth better camouflage from predators during the Industrial Revolution, and thus individuals with that phenotype had an advantage.
Natural selection acts on populations over many generations, and occurs due to beneficial traits of individuals. This can be seen in this lab: the beneficial traits that pinchers and knucklers had to pick up food caused their genes to be passed on more often (survived more often), and thus the population's gene pool was affected.
This unit was a tour in the essential "study of house," a branch of biology that grows in importance every day due to the numerous causes of damage to the environment. Ecology can be studied on many levels, from the smallest niches, full of factors and adaptations species need to survive; to complex food webs, structures linking hundreds or even thousands of producers and consumers of every trophic level, transferring less and less energy until apex predators get close to none; to entire ecosystems, rich with different organisms and the abiotic factors that affect their lives, as well as cycles of the nutrients they need; to the biosphere itself, extending worldwide and encompassing all life on earth.
Human population growth diagram
Likely the most directly linked topic to humans is human population, which, like populations of any animal, is affected by factors such as immigration, disease, density, and dispersion. Like any population in its initial stages, the human population is also growing exponentially, though the carrying capacity of the earth can only support about 10-15 billion in total.
One of the largest concerns currently is humans' effect on the planet. Through climate change, overexploitation, and introduced species, and habitat loss, we have created the sixth mass extinction, and have endangered a large percentage of all species. Unless we work as individuals and a society to conserve and restore resources and save biodiversity, the world as we know it will surcease.
Ball-and-stick model for polyethylene terephthalate (PET)
This unit has indeed left me with some unanswered questions, such has how exactly our harmful, as well as restorative, processes work. (e.g. power plant and engine emission chemistry, properties of plastics and recycling for different plastics) A further exploration into basic economics and manufacturing could also help me broaden my knowledge, as would knowing more about the largest threats to the environment. What are the main causes of introduced species in the modern world? What industries and specific techniques should be targeted to reduce habitat loss and overexploitation?
Much of the time we spent in this unit was working on a Conservation Biologist Project. In my group, we worked to create an effective presentation (see above) covering the environment and threats of the Ecuador cloud forests, as well as attempting to formulate solutions directed at these threats. Most of the time, we worked together well as a group, fulfilling group goals and individual tasks on schedule, and we were equally successful with our research. It was a bit difficult to coordinate large tasks as a group, such as putting together the works cited and getting the individual recordings done for editing, but in the end we were able to keep everyone, for the most part, on schedule, and wrapped up the work on time. If I were to do a similar project in the future, I would probably be more specific and break down goals. Furthermore, I would try to enforce goal deadlines better so that group members finished tasks on time without fail.
A concept we learned was the different conflict management types: assertive, passive, aggressive, and passive-aggressive. After taking a self-assessment on the topic, I determined that my leading types were assertive (35%) and passive (27%); my goal is to be more assertive, which would entail being more clear and straightforward with my ideas, as well as keeping my priorities in mind as I communicate.
In general, I look forward to learning more in the realm in biology, whatever it may be. On a side note, I will also work toward improving my writing, whether it be in biology reflections, or in any number of other applications.
