Consider the following scenario:
A drought hits the habitat of a semi-aquatic bird population. All ponds dry up, and fish populations decline. There are two groups of birds in the population that differ in leg length and diet. Long-legged birds eat fish, while short-legged birds eat insects. The drought has little effect on insect populations.
What is the main selective pressure in this scenario?
Insect population
Leg length
Fish population
Drought
The main selective pressure in this scenario is the drought. The drought has caused the ponds to dry up, leading to a decline in fish populations which affects the long-legged birds that rely on fish as their main food source. The short-legged birds, however, are not as affected by the drought as their main food source, insects, remains largely unaffected. Therefore, the drought is the main selective pressure as it directly impacts the availability of food (fish) for the long-legged birds.
Which statement is accurate about variation?
Organisms with variation in advantage, or more likely to survive
In all cases, variations of fact, how likely is it that an organist and reproduces
In all cases variations, become more common in a population
Organisms with variations are less likely to pass these variations to the offspring
The accurate statement about variation is: organisms with variation are more likely to survive. Variation in a population provides individuals with different traits, some of which may be advantageous in a changing environment. These advantageous traits increase the chances of survival and reproduction, leading to the passing on of these variations to future generations.
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.
Which term best describes the Browns scales.
Predominant phenotype
advantageous traits
Inactivated gene
New mutation
The term that best describes the brown scales in this scenario is advantageous traits. The brown scales provide an advantage to the fish by making them harder for predators to see in the muddy lake environment. As a result, the fish with brown scales are better protected and more likely to survive and reproduce compared to the fish with silver scales. This advantageous trait allows the fish with brown scales to pass on their genes and increase their representation in the population.
How did the Industrial Revolution impact the population of peppered moths in Britain?
The industrial revolution caused the proportions of each color morph in the population to become equal.
The light-colored moths became more common
The Industrial Revolution caused the proportion of each color morph in the population to become unequal
The dark colored moths became more common
The Industrial Revolution caused the proportion of each color morph in the population of peppered moths in Britain to become unequal. Prior to the Industrial Revolution, light-colored moths were more common and better camouflaged against light-colored trees. However, with the increase in pollution and soot from industrial activities, the trees became darker due to soot deposition. This change in the environment resulted in darker trees, making the dark-colored moths better camouflaged. As a result, dark-colored moths became more common in the population as they had a higher survival rate, while the proportion of light-colored moths decreased.
Why is the cheetah gene pool small today?
Inbreeding in zoos
Poor adaptability
Multiple bottleneck events
Lack of advantageous traits
The cheetah gene pool is small today primarily due to multiple bottleneck events. Throughout their evolutionary history, cheetah populations have experienced significant reductions in population size, leading to a loss of genetic diversity. These bottleneck events can result from factors such as habitat loss, hunting, and disease outbreaks. As a consequence, the surviving cheetahs have a limited gene pool, which makes them more susceptible to genetic disorders and reduces their ability to adapt to changing environments. Inbreeding in zoos also contributes to the small gene pool of cheetahs, as mating between closely related individuals further decreases genetic diversity. Poor adaptability and lack of advantageous traits may be secondary factors influenced by the reduced genetic diversity but are not the primary reasons for the small cheetah gene pool.
What change is observed in a distribution for a trait affected by directional selection?
It shifts to the left.
It shifts either to the right or to the left
It shifts to the right and to the left
It shifts to the right