Geologic Timeline Reflection

        This unit, I worked in a group and created a geologic timeline of the history of the Earth. The timeline gave a sense of the magnitude and major events of the past, as well as how insignificant of a time we humans have occupied. I have organized some thoughts below as a sort of reflection on the project and what we learned.

Mesozoic Era and the K-T extinction

         In the Earth's history, some significant events were the oxygen revolution, Cambrian explosion, and K-T extinction. The oxygen revolution, which occurred in the Proterozoic Eon, had a lasting and important impact on the Earth. Scientists have found that there was a radical increase in oxygen levels due to the photosynthetic actions of cyanobacteria; it has been estimated that the amount of oxygen went from 1% to 15% of current levels, and changed. Thus, this event affected the future of the Earth and made possible the proliferation of oxygen-respiring organisms afterward. The Cambrian explosion was also one of the most important events: it consisted of a burst of immense evolution and diversification that took place in an "explosion." The organisms arose in a mere 30 million years, and began many of the lineages that persisted for millennia, and that we see today. This was the cause of the development of both terrestrial flora and fauna, but also the marine life of the Ordovician and Devonian Periods. Lastly, the K-T extinction was highly influential to the development of the following Cenozoic Era. It saw the extinction of all dinosaurs and many other species, and allowed the adaptive radiation of the unaffected species and organisms, such as mammals. Thus, it made possible much of what exists today, including our own species, that would otherwise not have risen to such a degree.

Cenozoic Era and the blink of an eye that is us

        The scale of Earth's history is simply colossal, what with our own written and evolutionary history not even a blink of an eye in the planet. Though I had some idea of this comparison, especially as I had researched the topic as part of my 20 Time project, I was unaware of the vast difference of the eons and epochs. That said, we have had a surprising impact on the planet during our relatively short time here: we have changed the climate, the temperature, the geography, the topography; we have decimated many species, and allowed others to become widespread to further our own ends; we have spread and sought in space, and plumbed the deepest trenches of the Earth. As much as we have learned, we have destroyed, and there is no question that we will continue to do so. Perhaps through this, we are our own demise; just another species that formed, thrived, and died out as it made way for others to dominate. Are we just another Dinosauria? In all the ways we think ourselves superior, certain adaptations bequeathed similar advantages upon other species of the past. Flight, camouflage, speed, different senses: they all shone through and thrived, though the species changed and diverged. Are we different from all that came before us? What will come after us? Will we ever know? Perhaps not. But that is, inherently, our advantage: the unceasing yearning to know, to learn, to grow.

Unit 8 Reflection

        In this unit, we learned about evolution and its related processes and patterns. Evolution is a theory supported by numerous sources of evidence, such as analogous structures, where different species develop the same structures in different ways due to its benefits; developmental evidence, which can show processes shared in common by related species; homologous structures, which can show structures that have been adapted differently by diverging species; and fossils, which form a fossil record that can be used to track evolution across time. Evolution is mostly dependent on natural selection, though it is also affected by genetic drift, random changes in the population; gene flow, the movement of alleles; mutations, which influence and are acted on by natural selection; and sexual selection, a similar process involving selection for traits advantageous for mating success.

Result of artificial selection in carrots

        Like artificial selection, a process involving breeding a population for certain traits favored by humans, natural selection is a change in allele frequency in a population over generations. It occurs due to survival benefits certain traits give individuals. In addition, though the gene pool changes continuously over time due to natural selection, lethal alleles can remain as recessive alleles that may be influential in the event of changing conditions.
        As the population changes, patterns such as stabilizing selection, directional selection, and disruptive selections can appear. These relate to how different phenotypes become more less common, favoring an extreme, the intermediate, or both extremes. Disruptive selection is also a cause of speciation. Speciation occurs as new species rise due to behavioral, geographical, or temporal isolation. This can occur continuously, through gradualism, or in uneven stretches, as in punctuated equilibrium.

Allele frequency change over time in Hunger Games lab

        In a nutshell, this unit has been a whirlwind of ideas that tie in old concepts and new ones alike. (e.g. genetics, inheritance, populations) It has given many answers, though questions do not equally abound. For example, the information about homologous structures and fossils provoked questions about how these fossils actually change, and what genes control them. Partaking in the Hunger Games lab was particularly interesting, as it demonstrated real-time (or sped-up time really) how different factors play into the change in a population. Even the unexpected outcome still showed how genetic drift and new behaviors can affect what happens.Additionally, the vodcast on the history of life makes one wonder what exactly occurred that changed things so much. (go to my 20 time project to learn more!)
        In the last unit reflection, I made it a goal to more assertive, after exploring some of the different conflict styles. (e.g. passive, aggressive, assertive) Since then, I have put some effort into that goal, trying to put out a clearer opinion during group projects and, to some extent, in my life. For example, during a PE project, I made sure to maintain my priorities and to ensure we finished on time by keeping the group on schedule. I will continue to work toward this goal in the coming weeks, and I hope to be successful.
        All in all, I am looking forward to the next unit, and learning more about......kingdoms and phyla? That proves to be an adventure, and we shall see what it holds.