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sveta [45]
3 years ago
10

Describe the concept of natural selection, using the Galapagos finches as an example. Imagine you were trying to explain the con

cept to someone who did not know what it is.
Biology
1 answer:
Trava [24]3 years ago
4 0

Answer and Explanation:

Natural selection is the result of the phenotype-environment interaction which determines gene destiny in space and time, selecting beneficial alleles and increasing their frequency in the population. It is a consequence of the individual differential capability to reproduce and leave offspring. There must be also a genetic base called heritability. Natural selection involves interactions between individuals, the physical environment, and the biological environment.  

Natural selection results in adaptation, an increase of the aptitude phenotype.  In many cases, adaptations, resulting from natural selection, can be correlated to environmental factors or selective pressures applied by other organisms.

The selective agent is the environmental characteristic that determines the differential survival of the phenotypic classes.  

Some intraspecific phenotype variations follow a geographical distribution and can be correlated to changes in environmental conditions, such as temperature or humidity.  

Adaptive evolution refers to changes in the organism that lead to the evolution of the species and that are adaptive to certain conditions of the environment. Birds adapt to diverse ecological niches showing specialized beak forms to improve functions such as feeding, mating, defending, competing, and etcetera. These factors play an important role in beak shaping. Natural selection produces adaptive evolution.

During 1977 Daphne Major island went through an important drought, and many plant species produced few or no seeds during and after the event. The medium ground finch population, which is seed-feeder species, was hardly affected by this phenomenon. As seeds´ production dropped and the sizes of the extisting seeds were considerably smaller, the finch population declined drastically from about 1400 individuals to a few hundred in a period of two years, approximately. The fact is that the island weather controls plant species development, and thus, seeds availability as food for the birds. Years later after the drought, the finches population managed to recover but showing differences in the size of their beaks. Before the drought finches had a stubby beak and many years after recovering the average size of the beaks was larger than the beak size of the original population.  This difference in phenotype was due to the fact that during the drought, small seeds were very scarce, but large seeds with thick husks were still available. Small birds with small beaks starved because they were not able to open the husk and eat the interior of the seed. But those birds with bigger and stronger beaks were able to do so, and hence, managed to survive. The bird population adapted to the new environmental conditions and resource availability. Natural selection acted on the beak size, changing it.  

There are different kinds of natural selection, but in the present example, directional selection is operating.  

<u>Directional selection</u> increases the proportion of individuals with an extreme phenotypic trait, in this case, large beaks. This selection presents more frequently in those cases in which interactions between living organisms and the environment modify in the same direction.

Furthermore, beak size is not only related to feeding strategies, but also to reproduction. Female finches only mate with males that have the same beak size.

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What distinguishes disruptive and directional selection pressures when both select for extreme genetic traits?
Stella [2.4K]

Answer:

Yes both are different. In directional selection one of the extreme traits is favored, whereas in disruptive selection both the extreme traits are favored.

Explanation:

Directional: If selection acts to eliminate one extreme form and supports the other extreme then the peak shifts in the direction which is selected by the nature.

Disruptive: If the selection does not favor the mean character value, rather favors both the peripheral character values then this kind of selection is called disruptive selection.

5 0
3 years ago
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Can a virus metabolism
Alina [70]
Defects in transcription factors underlie some forms of cancer.
7 0
3 years ago
What conclusions can we draw from the lab about photosynthesis and cellular
GuDViN [60]

Answer:

Carbon dioxide and oxygen are recycled through photosynthesis and cellular

respiration forever unless something interrupts.

Explanation:

Photosynthesis and cellular respiration are two distinct and opposite metabolical processes undergone by living cells. They are opposite processes because one utilizes the products of the other as reactants.

Photosynthesis is a unique process to autotrophic organisms like plants. It is the process whereby plants synthesize their food in form of organic molecules (glucose) by combining Carbondioxide (CO2) and water (H2O) in the presence of sunlight.

The overall equation of photosynthesis is as follows:

6CO2 + 6H2O ------> C6H12O6+ 6O2

On the other hand, cellular respiration is the process whereby living cells obtain energy (ATP) by breaking down food molecules (glucose) using oxygen to produce carbondioxide (CO2) and water as products. The overall equation is:

C6H12O6 + 602 -----> 6CO2 + 6H2O

Based on the lab experiments, it can be concluded that Carbon dioxide and oxygen are recycled through photosynthesis and cellular

respiration because photosynthesis recycles/reuses the products of cellular respiration, which are C02 and H2O while cellular respiration recycles/reuses the products of photosynthesis, which are C6H12O6 and O2. This process occurs naturally in the environment and will continue to do so unless something interupts.

Option B is incorrect because light energy from the sun powers photosynthesis while option C is incorrect because photosynthesis transforms light energy to chemical energy while cellular respiration transforms chemical energy to thermal energy.

7 0
3 years ago
5 Which statement belongs in the region marked X? rudy made this Venn diagram comparing interphase and cytokinesis. O is the lon
Romashka [77]

Question:

Trudy made this Venn diagram comparing interphase and cytokinesis.

Which statement belongs in the region marked X? (image attached)

Answer options:

  • Is the longest stage
  • DNA is copied
  • The number of nuclei doubles
  • The number of cells doubles

Answer:

  • The number of cells doubles

Explanation:

Cytokinesis describes the splitting of the cytoplasm after mitosis. During interphase, the DNA is replicated. During mitosis, the DNA condenses into chromosomes, and the chromosomes are aligned and separated to opposite ends of the cell. During cytokinesis, the cell separates into two daughter cells.

6 0
3 years ago
Which of the following statements is true?
mr Goodwill [35]

Answer:

Spongy bone is well adapted to accept stress in many directions, which makes it good for shock absorption

Explanation:

Spongy bone tissue is less compact and always present towards the interior of the bone and is covered by compact bone. Spongy bone tissue has lamellae that are arranged in an irregular pattern. The thin irregular columns of lamellae are called trabeculae.

The trabeculae of spongy bone tissues are precisely arranged along the line of stress. This feature of spongy bones allows them to resist the stress applied from many directions and to transfer the force making them a good shock absorber. The final arrangement of trabeculae is achieved only after the person learns the locomotory movements completely.

4 0
3 years ago
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