Define the term “variations” in the context of natural selection
Variations refer to differences in traits or characteristics among individuals within a population. These variations can be passed down from one generation to the next through genetic inheritance. In the context of natural selection, variations are important because they provide the raw material for evolution to occur. Individuals with beneficial variations that increase their chances of survival and reproduction are more likely to pass on these traits to future generations, leading to changes in the overall population over time. By selecting for individuals with advantageous variations, natural selection drives the process of evolution.
Consider the following scenario: In a muddy lake environment, some fish have brown scales. Most fish, however, have silver scales. Predators have a harder time seeing the fish with brown scales. What term best describes the brown scales?
The term that best describes the brown scales in this scenario is "adaptation." The brown scales provide a beneficial advantage to the fish living in the muddy lake environment by making them less visible to predators. This trait increases their chances of survival and reproduction, as they are more likely to evade predation compared to fish with silver scales. This adaptation enhances the fitness of the fish with brown scales in their specific environment, illustrating the concept of natural selection in action.
How did the Industrial Revolution impact the population of peppered moths in Britain?
The Industrial Revolution had a significant impact on the population of peppered moths in Britain. Prior to the Industrial Revolution, the peppered moth population consisted predominantly of light-colored, or "peppered," moths, which were well-camouflaged against lichen-covered tree trunks. However, with the onset of industrialization in the 19th century, factories began emitting large amounts of pollution, primarily in the form of soot and other dark particles.
As a result, the tree trunks in industrialized areas became significantly darker due to pollution, making the light-colored moths more visible to predators. In this altered environment, the dark-colored, or "melanic," variant of the peppered moth had a higher survival rate as they were better camouflaged against the darkened tree trunks.
Over time, the population of peppered moths in industrialized regions shifted towards a higher proportion of melanic moths, as they had a selective advantage in the polluted environment. This shift in the moth population is a classic example of natural selection in action, demonstrating how environmental changes can drive evolutionary changes in species.
Why is the cheetah gene pool small today?
The cheetah gene pool is small today primarily due to a genetic bottleneck that occurred in the past. A genetic bottleneck is when a population undergoes a sharp reduction in numbers, leading to a loss of genetic diversity.
Historically, cheetahs faced multiple threats such as habitat loss, hunting, and competition with other predators, which drastically reduced their population size. As a result, only a small number of cheetahs survived and reproduced, leading to a genetic bottleneck.
With a small gene pool, cheetahs have reduced genetic diversity, which can make them more vulnerable to genetic disorders, diseases, and other environmental challenges. Inbreeding depression, where individuals with similar genetic backgrounds mate and pass down harmful recessive traits, is also a concern in populations with limited genetic diversity.
Conservation efforts are being made to address the genetic issues facing cheetahs, such as captive breeding programs and translocation of individuals to increase genetic variability and ensure the long-term survival of the species.
There are two varieties in a population of squirrels: short tails and long tails. Long-tailed squirrels are better at jumping and balancing in trees. Scientists observe that over the span of 100 years, the proportion of the population with long tails increases from 10% to 60%. Why are the short-tailed squirrel population decreasing?
The short-tailed squirrel population is decreasing due to natural selection favoring the long-tailed squirrels in their environment. In this scenario, long-tailed squirrels have a selective advantage over short-tailed squirrels because their long tails provide them with better jumping and balancing abilities in trees. As a result, long-tailed squirrels are more successful at obtaining resources such as food, evading predators, and mating, leading to higher survival and reproductive rates compared to short-tailed squirrels.
Over time, as long-tailed squirrels outcompete short-tailed squirrels and pass on their advantageous trait to their offspring, the proportion of long-tailed squirrels in the population increases. Meanwhile, the lower fitness of short-tailed squirrels results in a decrease in their numbers as they are less able to thrive in their environment.
This process of natural selection drives the change in the relative frequencies of the two squirrel varieties in the population, with the long-tailed variety becoming more prevalent over time due to their better-adapted traits.