Biology Honors: Natural Selection

What is a well known four word phrase for natural selection?

"Survival of the fittest"

What are some misconceptions of natural selection?

1. A population doesn't acquire new traits; these traits already existed in the population. But due to natural selection, these traits become the average. 2. Natural selection occurs over a long period of time, longer than the lifetime of an organism.

How is it possible for the white Evodots to make most, if not all of the population in the last generation? Provide 3 different scenarios.

1. When you click "run", if the background turns white instead of black, then the white dots won't be visible to the predator. 2. If the white dots are smaller, then it will be harder for the predator to click (eat) them. 3. If the white dots are faster, then it will be harder for the predator to click them.

If we started with only 2-pronged bean eaters, what percent of the population will be 2-pronged bean eaters? What would the graph look like?

100% Graph: y-axis -percentage of population that is 2-pronged x-axis -Generations Line - straight line at y = 100%

Using the fitness graph (figure 1) in the Fitness Curves: Variation & Fitness worksheet, if the initial average beak length of a population was less than 19mm then the population will evolve towards...

12mm average beak length

Using the fitness graph (figure 1) in the Fitness Curves: Variation & Fitness, if the initial average beak length of a population was more than 19mm then the population will evolve towards...

26mm average beak length

P = 0.05 means...

5% chance of being random

P = 0.9 means...

90% chance of being random

What is natural selection?

A process by which the traits of a population change due to inherited differences in the ability of individuals to survive and reproduce. Another definition from Google: Natural selection is the process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment. Over time, species will become more adapted to their environment.

What is artificial selection?

Artificial selection is selective breeding, where two parents with desirable traits are bred together to reproduce a baby with the traits.

Differential survival and reproduction leads to ____________

Change in the population

Reproduction + limited resources = __________

Competition

What are 2 examples of artificial selection?

Corns and carrots (see pictures of first corns and carrots before selective breeding)

Competition + genetic variation = __________

Differential survival and reproduction

If a fitness curve graph has 2 peaks, what type of selection will happen over time?

Disruptive

In the bean eaters lab, we only observed 5 generations. If we conducted the lab for a longer period of time, what would happen to the population of the 2-pronged bean eaters and 4-pronged bean eaters?

Due to natural selection and the competition the 2-pronged bean eaters will probably die out. The 4-pronged bean eaters will experience exponential growth UNTIL overpopulation occurs and the feeding area is too crowded. If the feeding area is too crowded, then competition will increase, causing some 4-pronged bean eaters to also die.

What is sexual selection?

In a species, the female (usually) chooses a mating partner based on: Size Strength Coloration Ability to provide Etc.

What are 2 examples of stabilizing selection?

Lizard population: The percentage of average length tailed lizard increased and the percentage of the extremes are even less. Babies: The percentage of babies with average weight increased and the percentage of the extremes are even less.

In the Evodots lab, when "heritable" was unchecked, was there a big change in the percentage of the various color of dots between the first generation and the last? Why or why not?

No. Since traits aren't hereditary, the black dots do survive and reproduce, but are more likely to reproduce different color dots. So in the last generation, the percentage of various color dots were random.

What are 2 examples of directional selection?

Peppered moth population: The percentage of melanic peppered moths increased and became the new average. Rock pocket mouse population: The percentage of dark rock pocket mouse increased and became the new average.

What are 2 examples of disruptive selection?

Swallowtail butterfly population: The average swallowtail butterfly's wing pattern became an extreme and two new average wing patterns were created. Rabbit color: The average rabbit fur color became an extreme and two new average fur colors were created.

How would the bird population evolve in Maui? (Use figure 2 graph in the Fitness Curves: Variation & Fitness worksheet)

The best beak lengths for the birds are 8mm, 20mm, and 28mm. If the initial average beak length of the population was: <14mm then it would evolve toward 8mm >14mm but <24mm then it would evolve toward 20mm >20mm the average beak length would evolve toward 28mm. In short, 3 new species or bird groups will be created.

If the P value is more than 0.05 then...

The difference between the two groups is a result of random chance.

If the P value is less than 0.05 then...

The difference between the two groups is significant and may not be a result of random chance.

What is adaptation?

The fitness of a population increases over time due to changes in the proportions of various traits. The proportion of various traits change over time as a result of competition.

What is P value?

The probability that the difference between the two groups is a result of random chance.

Why is it better to have a larger sample size?

With a larger sample size, the possible errors in the sample will not likely affect the data or conclusion of the experiment. In short, a larger sample size will produce more accurate results.

Is evolution related to natural selection?

Yes, definitely. Natural selection is the driving force of evolution. Without this process, populations won't be able to adapt and evolution won't occur.

In the Evodots lab, when "heritable" was checked, was there a big change in the percentage of the various color of dots between the first generation and the last? Why or why not?

Yes. Due to natural selection, the black dots made up 100% of the population in the last generation.

If traits are not hereditary, then the traits of the parent and the baby are __________.

different

In disruptive selection, populations will evolve toward the nearest...

peak of fitness (on the fitness curve graph)

Disruptive selection can create new _______.

species

If traits are hereditary, then the traits of the parent and the baby are ________.

the same