There are 2 types of worms: worms that eat at night (nocturnal) and worms that eat during the day (diurnal). The birds eat during the day and seem to be eating ONLY the diumal worms. The nocturnal worms are in their burrows during this time. Each spring when the worms reproduce, they have about 500 babies but only 100 of these 500 ever became ald enough to reproduce.
a. What worm has natural selection solocted AGAINST?
Darwin’s 5 points: Identify the 5 points in the scenario above.
Fopulation has variations. Some variations are
favorable.
More offspring are produced than survive.
Those that survive have favorable traits.
A population will change over time.
2) There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones with medium coats. It is fall, soon to be winter. The temperatures are dropping rapidly and the bears must be kept warm. or they will freeze to death. Many of the bears have had-2 cuba each but due to the extreme temperatures, many mothers only have one cub left.
a. What bear will natural selection select AGAINSTY
Darwin’s 5 points: Identify the & points in the scenario above.
Fopulation has variations.
Some variations are favorable.
More offspring are produced than survive
Those that survive have favorable traits.
A population will change over time.
3)
In ostriches, there are 2 types: ones that run fast and those that run slowly. The fast birds can reach up to 40 miles an hour. Jackals love to eat ostrich, and they can reach speeds of up to 38-40 miles per hour. A flock of ostrich will lay 10 eggs (each mother only lays 1), but many rodents break into the eggs and eat the fetus before they hatch.
a. What ostrich will natural selection select AGAINST?
The Correct Answer and Explanation is :
1) Worms:
a. Natural selection is selecting against the diurnal worms. These are the worms that are active during the day, when birds are also active and feeding. Since the birds consume only the diurnal worms, these worms face higher predation and thus have a lower chance of survival and reproduction compared to the nocturnal worms, which are safe in their burrows during the day.
Darwin’s 5 Points in the Scenario:
- Population has variations: The worm population varies in terms of diurnal and nocturnal activity patterns.
- Some variations are favorable: Being nocturnal is a favorable trait as it avoids predation by birds.
- More offspring are produced than survive: Each worm produces about 500 offspring, but only 100 survive to adulthood.
- Those that survive have favorable traits: Nocturnal worms, which avoid predation by being active at night, are more likely to survive.
- A population will change over time: Over time, the proportion of nocturnal worms may increase as they have a higher survival and reproductive success.
2) Polar Bears:
a. Natural selection is selecting against polar bears with thin coats. As temperatures drop, bears with thicker coats have a thermal advantage, enabling them to keep warm and survive harsh conditions, thereby maintaining their health and increasing their chances of reproductive success. In contrast, bears with thin coats are less insulated, more likely to suffer from the cold, and therefore more likely to succumb before reproducing.
Darwin’s 5 Points in the Scenario:
- Population has variations: Variations exist in coat thickness among polar bears.
- Some variations are favorable: A thick coat is a favorable variation in cold environments.
- More offspring are produced than survive: Each bear may have multiple cubs, but due to severe cold, many do not survive.
- Those that survive have favorable traits: Bears with thicker coats are more likely to survive and reproduce.
- A population will change over time: Over time, the gene pool will likely shift towards bears with thicker coats.
3) Ostriches:
a. Natural selection is selecting against slow-running ostriches. These ostriches cannot escape predators as effectively as the faster ones. Given that jackals can reach speeds close to the maximum speed of the fastest ostriches, the slower individuals are more likely to be caught and killed by jackals, reducing their chances of survival and reproduction.
300-word Explanation:
In the natural world, the concept of “survival of the fittest” often directly relates to an organism’s ability to avoid predation, secure resources, and reproduce. In the scenario with the ostriches, we observe a direct application of this principle. Ostriches, which are known for their remarkable speed, can run up to 40 miles per hour. This speed is crucial in evading predators like jackals, which can also run up to similar speeds.
The survival chances of any given ostrich depend significantly on its speed. Those that run fast enough to elude jackals are more likely to survive, while slower ones become easier targets. Since predators typically catch the slowest and weakest individuals, the genes for slower speeds are less likely to be passed on to the next generation. Conversely, faster ostriches not only survive more often but also have the opportunity to reproduce, passing their genes for higher speed to their offspring.
Over time, this selective pressure results in a population where the average speed may gradually increase, a process known as directional selection. Directional selection favors traits at one end of the trait spectrum — in this case, higher speed. This evolutionary pressure shapes the gene pool, promoting traits that enhance survival and reproductive success under the prevailing environmental conditions.
Moreover, this scenario illustrates the brutal reality of natural selection, where environmental pressures—predation in this case—directly influence which individuals survive to reproduce. This dynamic is a powerful force driving the evolution of species, reinforcing traits that are best suited to the current environment, thus shaping the biological characteristics of future generations.