Question

How Does Evolutionary Change Occur? "I soon perceived that selection was the keystone of man's success in making useful races of animals and plants. But how selection could be applied to organisms living in a state of nature remained for some time a mystery to me." - Charles Darwin Introduction Fundamentally, evolution is the idea that the form and behaviors of a species are not fixed - that they can change over time. Before Darwin was even born, some scientists had questioned the immutability of species (the idea that species could not and did not change over time). The eventual success of Darwin's explanation rested, in part, on the mechanism by which he suggested that evolution could occur. In this activity, you will explore this mechanism, which Darwin referred to as “natural selection." Natural selection is basically a process that results in differential reproductive success between individuals who differ in some trait or traits. (Differential reproductive success means that some individuals leave more offspring than others.) For natural selection to occur, the following must be true: 1. Individuals vary (individuals are not identical). 2. Some variations are heritable (offspring resemble their parents - the variation is genetically based). 3. More offspring can be produced than the environment can support (for example, if there is resource limitation) 4. Some variations must make an individual better-suited to their environment. If number 3 is true, then not all offspring will survive to reproduce. If some variations are better- suited to a particular environment than other variations (number 4), then individuals with those beneficial variations will be more likely to survive and reproduce. The result is that the beneficial variations become more common in the population and the species changes over time. To make this clearer, think about the following example. Imagine a species of small, tropical fish. Most individuals of this species have brightly colored scales, others are drab and blend in with the bottom of the streams in which they live. Brightly colored fish have brightly colored offspring and dull colored fish have dull colored offspring. Because of a flood, a big fish that eats the species of small tropical fish has moved into the streams where the small tropical fish lives. In the stream, there are a limited number of hiding places for the small fish to escape from Crisp (1).pdf Det

Answer 1

ANSWER TO THE PASSAGE :

1. It is evident that the bright colored fish is easily susceptible to be preyed upon mainly because of its appearance and it does not have the ability to get camouflaged with the bottom surface.
2. On the other hand, it can be seen that the dull colored fish is well adapted to survive the predation and hence it can be seen the genes which are responsible for the bright coloration will disappear over time or the frequency of the gene will get drastically reduced whereas on the other hand the gene (allele) associated with the dull color will increase in its frequency and in some instance can get fixed depending upon the selection pressure in the form of predation.

ANSWER PART 1 :-

In this case, as the background it black, those beans which tends to merge will with this background tend to hide well remaining undetected from the predators.

ANSWER PART 2 :-

In this case, there is a multi-colored background which supports the hiding place for multiple colored beans rather than a single colored or dark bean as in case of the black background.

ANSWER 1 :-

1. In the above mentioned part 1, it can be seen that the color of the seed was under selection with black being the one able to camouflage well and increase its frequency as compared to the other seeds.
2. It can be stated that the predation or consuming of these beans was acting as a selection pressure only choosing those traits in the beans helping the beans survive the predation.

ANSWER 2 :-

1. In the above experiment, it can be seen that, before the start of round two, there is production of offsprings as can be seen in the form of doubling of the original seed content. This indicates that at the end, the species which survive will reproduce more offsprings and this continues through all the rounds enhancing the chances of survival. This indicates that more offsprings can be produced in response to selection than the capacity of the environment to hold that much amount.
2. It can be seen that there are around five different traits of seeds that are considered and this indicates that the individuals vary and it can also be seen that these varied characters are being transferred to the next generation or next round of simulation.
3. The last point to be included is some of the varied traits enhance the survival of the beans as compared to the other traits and in this case, it is the back colored trait that supports survival.

ANSWER 3 :-

Gene is basically a sequence of DNA which encodes for a particular character by means of bringing about the appearance of the character or a particular body phenomena by means of producing a particular proteins such as a protein which can synthesize the coat color of the seeds.

If the gene undergo minor changes in the form of mutations, this would result in the changes which are transcribed into the phenotype and hence it can be said that the variations are in the form of genetic changes.