natural selection worksheet
directions: read each scenario and answer the questions about natural selection. identify what traits are selected for and against, the selective pressure, and how each of darwins 4 principles of natural selection appear in each situation.
scenario 1: worm activity
there are 2 types of worms: worms that eat at night (nocturnal) and worms that eat during the day (diurnal). birds eat during the day and mostly eat the diurnal worms. the nocturnal worms are hidden in their burrows. each spring, worms have about 500 babies, but only 100 survive to reproduce.

a. what trait is selected against? ____________________ for? ____________________
b. what is the selective pressure? ____________________________________________
c. darwins 4 points:
- populations have variations: ____________________________________________
- more offspring are produced than survive: _______________________________
- those that survive have favorable traits: _______________________________
- a population will change over time: _______________________________
image of a cartoon worm

Question

natural selection worksheet
directions: read each scenario and answer the questions about natural selection. identify what traits are selected for and against, the selective pressure, and how each of darwins 4 principles of natural selection appear in each situation.
scenario 1: worm activity
there are 2 types of worms: worms that eat at night (nocturnal) and worms that eat during the day (diurnal). birds eat during the day and mostly eat the diurnal worms. the nocturnal worms are hidden in their burrows. each spring, worms have about 500 babies, but only 100 survive to reproduce.

a. what trait is selected against? ____________________  for? ____________________
b. what is the selective pressure? ____________________________________________
c. darwins 4 points:
- populations have variations: ____________________________________________
- more offspring are produced than survive: _______________________________
- those that survive have favorable traits: _______________________________
- a population will change over time: _______________________________
image of a cartoon worm

Accepted Answer

### Part a
# Brief Explanations:
- Selected Against: The diurnal trait (eating during the day) is selected against because birds eat during the day and mostly eat diurnal worms, so this trait makes them more likely to be preyed upon.
- Selected For: The nocturnal trait (eating at night) is selected for because these worms are hidden in burrows during the day when birds are feeding, so they are less likely to be eaten and more likely to survive.
# Answer:
Selected AGAINST: diurnal (eating during the day)
Selected FOR: nocturnal (eating at night)

### Part b
# Brief Explanations:
Selective pressure is the factor that influences survival and reproduction. Here, the presence of birds that eat during the day and prey on diurnal worms is the selective pressure, as it affects which worm traits are favorable for survival.
# Answer:
The selective pressure is predation by birds (birds eating during the day and preying on diurnal worms).

### Part c - Darwin's 4 Points
#### 1. Populations have variations:
# Brief Explanations:
In the worm population, there is variation in activity time - some worms are diurnal (active during the day) and some are nocturnal (active at night). This shows the variation within the population.
# Answer:
There are two types of worms: diurnal (eat during the day) and nocturnal (eat at night) - this is the variation in the population.

#### 2. More offspring are produced than survive:
# Brief Explanations:
The scenario states that each spring, worms have about 500 babies, but only 100 survive to reproduce. This directly illustrates that the number of offspring produced (500) is greater than the number that survive (100).
# Answer:
Worms have about 500 babies each spring, but only 100 survive to reproduce - more offspring are produced than survive.

#### 3. Those that survive have favorable traits:
# Brief Explanations:
Nocturnal worms are hidden in burrows during the day when birds (predators) are active, so they are less likely to be eaten. Thus, the nocturnal trait (favorable trait) allows them to survive, while diurnal worms are more likely to be eaten by birds and less likely to survive.
# Answer:
Nocturnal worms (with the trait of eating at night) are hidden in burrows during the day, so they are less likely to be eaten by birds and survive. Diurnal worms are more likely to be eaten, so the surviving worms (nocturnal) have the favorable trait of being active at night.

#### 4. A population will change over time:
# Brief Explanations:
Over time, since nocturnal worms are more likely to survive and reproduce (as they are less preyed upon), the proportion of nocturnal worms in the population will increase. This means the population's trait (activity time) will change, with more nocturnal worms over successive generations.
# Answer:
Over time, the proportion of nocturnal worms in the population will increase because they are more likely to survive and reproduce, so the population will change to have more nocturnal worms.

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QUESTION IMAGE

Question

Explanation:

Part a

Answer:

Part b