he graphs below describe pelvic spine length in an isolated population of threespine sticklebacks at the start and end of a time period long enough for natural selection to occur. At the start of this time period, the threespine sticklebacks' environment changed.
Describe how the threespine stickleback population changed over this time period. Use the theory of natural selection to construct a possible explanation for this change.
The percentage of sticklebacks with long pelvic spines
in the population. This suggests that sticklebacks with short spines were
likely to survive and reproduce than sticklebacks with long spines. This may have occurred because there were significantly
large fish after the population's environment changed. So sticklebacks with long spines were
likely to be caught by predators than sticklebacks with short spines.
Answer (1)
Based on the descriptions, it seems like the population of threespine sticklebacks changed over time in response to the environment. Initially, there was a certain distribution of pelvic spine lengths, but by the end, the proportion of sticklebacks with long spines decreased.Using natural selection to explain this, it looks like the environment changed in a way that made having a long pelvic spine less advantageous. For example, the presence of larger fish or predators might have increased, and these predators were more likely to catch sticklebacks with long spines. Since sticklebacks with short spines were less likely to be caught and eaten, they had a better chance of surviving and reproducing. Over time, this led to a higher number of short-spined sticklebacks in the population.In simple words, the environment changed in a way that favored sticklebacks with short spines because they had a better chance of surviving the new conditions. This is a good example of natural selection, where the traits that help organisms survive and reproduce become more common in the population[tex].[/tex]
