What is Gene Selection? Frequency? The process by which forms of - - PowerPoint PPT Presentation

What is Gene Frequency? What is Natural Selection?

Gene frequency is the frequency

• f occurrence or proportions of

different alleles of a particular gene in a given population. It is usually expressed as a proportion

• r a percentage, and describes

the amount of genetic diversity at the individual, population, or species level. (1) The process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.(1)

How can Natural Selection and Allele Frequencies effect one another?

• Natural Selection can increase or decrease an alleles frequency. If

the allele produces a phenotype which is advantages then their frequency will increase, however if it is not advantageous, the frequency will decrease.

• They both work together to accelerate evolution or against each
• ther to slow evolution.

Gene Frequency Methods

• Add all the beads in one cup and mixed
• Randomly pick two bead pairs to determine the phenotype and genotype and record the data
• Case1:

50 red beads, 50 white beads to create RR homozygous dominant, Rw heterozygous, ww homozygous recessive 33% deduction of ww homozygous recessive per generation for 6 generations

• Case 2:

50 red beads, 50 white beads to create RR homozygous dominant, Rw heterozygous, ww homozygous recessive 100% deduction of ww homozygous recessive per generation for 6 generation

• Case 3:

40 red, 40 white, 20 black beads to create RR homozygous dominant, Rw heterozygous, ww homozygous recessive, RB heterozygous mutation, Bw heterozygous mutation and BB homozygous mutation. 100% deduction of ww, 150% survival of RB, and 200% survival of BB homozygous for each generation for 6 generations

• Case 4:

40 red, 40 white, 20 black beads to create RR homozygous dominant, Rw heterozygous, ww homozygous recessive, RB heterozygous mutation, Bw heterozygous mutation and BB homozygous mutation. 100% deduction for ww, 100% deduction of BB, and 50% deduction of RB

Natural Selection Methods



1) Choose 40 same colored dots



2) 20 of those dots will go onto a colored cloth mat symbolizing an environment and the dots will symbolize species.



3) Predators: (only get 1 minute) Generation #1- one person, one hand Generation #2- one person, two hands Generation #3- two people, one hand Generation #4- two people, two hands * Environment is changed (new colored place mat) Generation #5- two people, two hand (lights going on and off) Generation #6- Natural Disaster(playing card)



4) Take count of dead for each generation and record data * If any colors/generation die out then a new color/generation will be added.



5) Each time we enter our results for each generation, we would add back the offspring for each back into the environment.

Gene Frequency Results

0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% Gen 1 Gen 2 Gen 3 Gen 4 Gen 5 Gen 6 Gen 7 Gen 8 Gen 9 Gen 10 Gen 11 Gen 12 Percent

• f

Popula on Genera on

Case 1:

• 33%

ww

RR-33%ww Rw-33% ww ww-33% ww

• 20.0%

0.0% 20.0% 40.0% 60.0% 80.0% 100.0% Gen 1 Gen 2 Gen 3 Gen 4 Gen 5 Gen 6 Gen 7 Gen 8 Gen 9 Gen 10 Gen 11 Gen 12 Percent

• f

Popula on Genera on

• Case

2:

• 100%

ww

RR-100% ww Rw- 100% ww ww-100% ww

Case#1 and Case#2 decrease in Rw and ww due to the negative selection of the ww genotype. Figure1 Figure 2

Gene Frequency Results

• 20%
• 10%

0% 10% 20% 30% 40% 50% 60% 70% 80% Gen 1 Gen 2 Gen 3 Gen 4 Gen 5 Gen 6 Gen 7 Gen 8 Gen 9 Gen 10 Gen 11 Gen 12 Percent

• f

Popula on Genera on

Case 3: Posi ve Muta on

RR Pos tve Muta on Rw Posi ve Muta on ww Pos ve Muta on RB Posi ve Muta on wB Posi ve Muta on BB Posi ve Muta on

• 60%
• 40%
• 20%

0% 20% 40% 60% 80% Gen 1 Gen 2 Gen 3 Gen 4 Gen 5 Gen 6 Gen 7 Gen 8 Gen 9 Gen 10 Gen 11 Gen 12 Percent

• f

Popula on Genera on

Case 4: Nega ve Muta on

RR Nega ve Muta on Rw Nega ve Muta on ww Nega ve Muta on RB Negai ve Muta on wB Negai ve Muta on BB Nega Muta on

Case #3: Increase in both Homozygous Dominant BB (200% survival) and Heterozygous dominant RB (150% survival) due to the positive mutation . Decrease in RR, Rw, ww, and wB due to neutral/negative survival. Case #4: RR, Rw, wB show little to no growth due to neutral survival. RB increased slightly due to 50% survival. BB and ww declined due to 0% survival.

Figure 3 Figure 4

Natural Selection Results

• Through generations 1-5 we were able to see natural selection at work as the phenotypes were

not well suited for the environment and were consistently killed off. Generation 6 we witnessed the bottle neck effect with the natural disaster. Figure 5 Figure 6

Natural Selection vs Allele Frequency

As long as the Phenotype is beneficial then the species will have a will have a positive compound annual growth rate %. Figure 7 Figure 8

Conclusion

 Natural selection acts more on the phenotype than on the

genotype.(2)

 Natural selection acts indirectly via how the genotype affects the

• phenotype. (2)

 Allele frequency can be changed by Natural Selection, gene flow,

and genetic drift, yet only Natural selection consistently improves the match between organisms and their environment. (2)

 Evolution is therefore achieved because of Natural Selection.

Citations

1)http://dictionary.reference.com/b rowse/gene+frequency 2)Reece, Jane B. "22 Descent with Modification: A Darwinian View of Life." Campbell Biology. 9.th ed. San Francisco: Pearson Benjamin Cummings, 2011. 460. Print. 3)https://solano.instructure.com/co urses “Hardy-Weinberg Law” lab instructions