Student Sheet On Natural Selection ✓ Solved

Name Student Sheetnatural Selection

Each of you is a member of a bird population with a wide variety of genetic variations with respect to beak type. Each group of 5 or 6 students represents one of the beak types found in the population.

Procedure:

  1. Your teacher will ring a bell to initiate the start of feeding.
  2. All the groups collectively, using only their beaks, will be given one minute to obtain food from a common feeding area and place the food into the “mouth” (test tube).
  3. Your teacher will ring a bell to terminate the feeding period.
  4. The pieces of food “eaten” by each “bird” will be counted, a group total calculated and recorded in the appropriate column on Table 1.
  5. The total “eaten” by the group will be reported to the teacher to obtain a class total. This figure is needed to determine the number of survivors (parents and offspring).
  6. Calculate the number of birds your group has earned by using the following formula: Survivors = total pieces eaten by your group / total pieces eaten by the population X total # of birds in the population.
  7. If your group ate relatively little food and thus earned fewer “birds” than you started with, some “birds” will die, turn in their beaks, and become offspring for other groups. If your group ate a lot of food, it will earn more “birds.” These “birds” will be drawn from the group of extras and get a beak that is the same as the group they will be joining.
  8. Steps 1 through 6 will be repeated 4 more times, thus accumulating five generations of data.
  9. Record data in Table 2.
  10. Graph all results, showing how the percentages of beak type in the total population changed over time.
  11. Write a summary of your observations.
  12. Submit report including written summary, data, and graph.

Table 1: Total Seeds Eaten Per Generation in Simulation

Identify each of your “beak” types:

  • Beak 1: ___________
  • Beak 2: ___________
  • Beak 3: ___________
  • Beak 4: ___________
  • Beak 5: ___________

Table 2: Percentage “Beak” Type in Total Population

Analysis:

  1. How does genetic variation allow a population to survive during environmental changes?
  2. How does natural selection control the genetic diversity found in populations?
  3. Using your knowledge of natural selection, explain how extinction occurs.

Paper For Above Instructions

Natural selection is the process through which certain traits become more prevalent in a population due to their advantageous nature in the given environment. This interactive activity illustrates natural selection using a bird population designed to replicate the survival of the fittest in a classroom setting. The students represent different beak types that have varying abilities to acquire food in a limited period, symbolizing the struggle for resources in nature.

Understanding the Procedure

The experiment began with the teacher ringing a bell to initiate feeding, where groups of students, each with a distinct beak type (represented by different objects they could use), aimed to gather as much food as possible within one minute. This competitive feeding mimicked natural food competition among birds in their natural habitats.

After the time was up, the amount or pieces of food collected by each group (beak type) were counted and recorded. This data collection reflects how researchers in biology track survival rates and reproductive success in natural populations. The total food collected by each group was then compared to the total collected by the class, leading to the calculation of how many "birds" each group retained for the next generation based on their food acquisition success.

The formula provided gives insight into how resources dictate population sizes and survival rates. Those groups that successfully gathered more food would reproduce more extensively than those that struggled, further driving the principles of natural selection forward.

Accumulating Generations

The activities were repeated for five generations, allowing students to observe changes over time in their respective populations. Each iteration provided insight into how those groups that managed to adapt (gather food efficiently) thrived while others diminished or went extinct. Thus, students witnessed firsthand how characteristics beneficial for survival can spread through populations, illustrating the concept of adaptive radiation in a tangible way.

Graphing the Results

The requirement to graph the results of food consumption highlighted the important concept of data visualization in scientific research. It helps in understanding trends, such as how certain beak types may dominate as time passes, representing a shift in population dynamics. This activity serves as a practical lesson on the importance of recording data and analyzing it as part of the scientific method.

Genetic Variation and Survival

Genetic variation is essential for the resilience of populations. It allows a population to have diverse traits, some of which may be better suited for survival in changing environments. For instance, if a drought occurs, those birds with beaks that can crack open tougher seeds may survive, while others may perish. This selected survival leads to the prevalence of favorable traits in future generations, providing a clear illustration of natural selection at work.

Natural selection controls genetic diversity by favoring particular traits over others depending on environmental pressures. If a particular beak shape becomes advantageous due to shifts in available food, those with that shape will reproduce more successfully, leading to a decrease in genetic variability over time as classes of traits become more pronounced.

Explanations of Extinction

Extinction can occur when a population cannot adapt swiftly enough to environmental changes or when genetic variation is insufficient to provide necessary adaptations. In the experiment, groups that failed to gather sufficient food over successive generations faced a decline in their population—a direct parallel to species in the wild that cannot meet natural demands due to habitat destruction, climate change, or predation pressures.

This iterative exercise highlights the delicate balance in ecosystems and the transient nature of species persistence. It showcases how intertwined genetic variations, environmental factors, and survival mechanisms converge to shape the world’s biodiversity.

Conclusion

Reflecting on this exercise signifies comprehension of natural selection principles, where survival hinges on the adaptations that allow different "beak" types to thrive. This simulated model captures the essence of ecological interactions, emphasizing the value of biodiversity and adaptation.

References

  • Darwin, C. (1859). On the Origin of Species. London: John Murray.
  • Mayr, E. (1963). Animal Species and Evolution. Cambridge, MA: Belknap Press.
  • Futuyma, D. J. (2013). Evolution. Sunderland, MA: Sinauer Associates.
  • Gould, S. J. (2002). The Structure of Evolutionary Theory. Cambridge, MA: Harvard University Press.
  • Ridley, M. (2004). Evolution. Oxford: Blackwell Publishing.
  • Stauffer, J. (2012). Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought. New York: Yale University Press.
  • Carroll, S. B. (2005). From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design. Malden, MA: Blackwell Publishing.
  • Patterson, C. (1999). Evolution. New York: Oxford University Press.
  • Allmon, W. D. (2001). Evolution and the Fossil Record. Maryland: University of Maryland Press.
  • Szathmáry, E. (2015). The Major Transitions in Evolution. Oxford: Oxford University Press.

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