ASSIGNMENT 1- Underst, anding Natural Selection

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  1. Describe your starting population (phenotypes):
1 N= 300 light green medium Slight curve
2 N= 300 light green medium Curved
3 N= 300 light green medium Medium Curve

N= The number of individuals making up the population; usually 300 each. You may need to wait for these numbers until after the 500,000 years has passed (the numbers will show up in the comparison of before , and after).

Did you select beak sizes for diversity OR to better equip the birds for the foods available in the southwest isl, and environment?

Yes, I selected the beak sizes to better determine the varieties of food available at the southwest environment. The beaks are chosen as an adaptive mechanism to different types of food which exist in the southwest environment. The birds which will contain traits which enhance their fitness are more likely to survive, and reproduce hence their continued existence. Those birds with traits which do not enhance fitness are more likely to fail to adapt to their new environment hence are more likely to become extinct. The projected simulation represents 500000 years, and this is the period in which any form of mutation is evident for observation using the naked eye.



A mountain range separates the southwest environment from the rest of the isl, and. This type of isolation can lead to SYMPATRIC or ALLOPATRIC (<circle one) speciation.

This is an example of allopatric speciation, and the reason behind such an answer is due to the presence of a physical barrier, and in this case the physical barrier is the presence of a mountain range that bars the mixing of genes between the two divides.

  1. Run these three initial bird populations through simulated selection for 500,000 years. Summarize major events, and approximately when they occur:

All my birds’ selections contain light green color hence all the three types will be well fitted with the light green foliage. However, the adapted to pick with availability of food the second bird selection curved beak will find it hard to fit in the environment due to absence of predators. There are only seeds, and edible insects for food, light green foliage with no predator

After 50000 years, there is a decline in number in bird 1, 2, and 3 as follows: 298, 297, and 168 respectively. However, the major change after 50000 years is the inheritance of a random mutation for a longer beak in bird 1. However, the mutation did not have any effect on fitness of the birds.

At 100000 years, in bird 1, a smaller number of offspring develops mutations with their beak becoming less curved, and this made the offspring to be more fit than the parent. They survived, and produced a phenotype that was more fitted. However, some unmated birds survived. Their numbers also increased unlike in bird 2, and 3 where the numbers were declining.

At 150000 years, bird 3 becomes extinct while bird 2 remains unaffected significantly in terms of numbers. In bird 1, a small number of offspring developed mutants but the mutation did not offer them fitness advantage. Over time, the phenotype disappears.

At 200000 years, a small number adopted mutants in bird 1. However, the phenotype is still less fit. Their body size is larger

At 250000, in bird 2, a small number of offspring inherits mutants. The mutation is not related to fitness but it makes them better mates. In bird 1, no changes take place apart from their increase in number.

At 300000 years, bird 2 offspring inherits mutants which make them more fit. They survive, and reproduce hence increasing their number. Bird 1 also increases in number but no mutations in offspring are recorded.

At 350000 years, a small number of offspring inherit a random mutation, and their beaks become shorter. The mutation did not increase fitness. In bird 1, there number continues to rise to 823

At 400000 years, a small number of offspring of bird 1 obtains random mutations. Their plumage becomes dark green. However, the mutation leaves the numbers constant but makes them susceptible to diseases.

At 45000 years, a small number of offspring attained mutation in bird 2, and the mutation made them more susceptible to diseases. The offspring died.



  1. Describe the populations after 500,000 years:
1 N= 1089  dark green plumage The size become bigger than the original size The beak becomes long
2 N= 685 Light Green Larger in Size The beak becomes less curved , and thick
3 N= 0 Light Green Smaller in Size No changes noted. The beak remains medium curved.

For this environment, which phenotypic characteristics are beneficial?

The type of beak is beneficial in this environment, and color of plumage which offers protection from other predators

What factor(s)/event(s) appear to have had the largest impact on generating change in your bird populations during the 500,000 years?

Gene mutation contributed a lot to the elimination of certain birds. This is as a result of genes the development of genes which were susceptible to diseases.

The shape and size of beak also contributed to easy selection of available food which led to the decrease of the birds or increase in number depending on the adaptability of their beaks to the available food.

  1. A hurricane has blown some of your birds over the mountains: Using evolution-terminology, what sort of event(s) result from the displacement of these birds to new areas of the isl, and?

Environment plays a role in the survival of species. A barrier prevented the birds from interacting to the other side of the environment, and this caused a type of speciation known as allopatric speciation. The break of this barrier by the hurricanes made it necessary for the birds to undergo mutations, and differentiation in order to adapt to the new environment.


Describe the new environments (including the one you designed): Summarize the foods available by listing the major food or if all foods available write “diverse”

Features Southeast Northwest Northeast
FOOD Plenty of Seeds Plenty of seeds Some food/ seeds
PREDATORS None Plenty Plenty
FOLIAGE Light Green Purple Green

In designing the Northeast environment did you choose features (food/foliage/low predators) to increase bird survival? Explain:

Yes, foliage provides camouflage against predators, and availability of food is important as nutrition plays a role in the natural selection of species. Plenty food means less competition for the scarce commodity hence less likely for the birds to become extinct



PREDICTION: Which group of birds (1, 2, or 3) is better adapted for each environment?


  Southeast Northwest Northeast
BIRD GROUP> Bird 2 Bird 1 Bird 3


  1. You ran the initial (all green) birds in one environment for 500,000 years…then you ran the post- hurricane birds for another 500,000 years. Usually, the ending bird populations show greater diversity. Was this the case for your simulation? YES NO
What explains your results?

Yes, the population with higher levels of diversity was bird one, and there was a continuous increase in their number.



Was your prediction (above) correct?

Yes. My prediction was correct

Which of the environments has the greatest, final, number of birds? (circle one>) SOUTHEAST NORTHWEST NORTHEAST what do you think is the reason for bird success in this environment?

North East has the greatest number of birds due to a higher availability of food, and light green foliage which act as a hideout for the birds.



  1. In terms of natural selection, how important is the environment?

Environment plays an important role in natural selection. First, it offers determines the kind of food available in it for natural selection to take place. Secondly, it plays an important role in harboring of species hence the climatic condition of such a place an important role in natural selection. Thirdly, disease prevalence is different depending on geographical location, , and this determines those that are resistant to diseases to attain natural selection.





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