Question

13.00 points possible | due sunday 11/23/25 at 11:59 pm
0/1 point
which of the following would be an example of evolution by natural selection? (select all that apply)
a population of moths is 50% yellow/50% white. a species of bird moves into the area and can only see the yellow moths. after 10 years 95% of the moths are white.
an herbicide resistant weed appears in a corn field, after 10 generations, all of the weeds are herbicide resistant.
bears usually come out of hibernation in april. in an abnormally warm year, the bears all emerge in march.
a tree grows on average 0.3 meters a year. in a particularly rainy year, the tree grows 0.5 meters.
this question was created or adapted by your instructor.

Explanation:

• Option A: The bird (a selective pressure) preys on yellow moths. White moths have a survival advantage. Over time (10 years), the frequency of the white - moth trait increases (from 50% to 95%). This shows natural selection as the environment (presence of the bird) favors certain traits (white color) in the moth population.
• Option B: The herbicide is a selective pressure. The herbicide - resistant weed has a survival and reproductive advantage. Over 10 generations, the non - resistant weeds are eliminated (presumably by the herbicide), and the resistant trait becomes fixed (all weeds are resistant). This is an example of natural selection where a trait (herbicide resistance) is favored in the presence of a selective agent (herbicide).
• Option C: Bears emerging from hibernation earlier in a warm year is a phenotypic plasticity (a non - genetic, reversible change in response to environmental conditions). There is no change in the genetic makeup of the bear population over generations. It is just a response to a short - term environmental fluctuation (temperature in a particular year), not natural selection.
• Option D: A tree growing more in a rainy year is a phenotypic change due to environmental conditions (more water). It is not a genetic change that would be passed on to future generations in a way that shows differential survival and reproduction based on a heritable trait. It is an example of environmental influence on growth, not natural selection.

Answer:

A. A population of moths is 50% yellow/50% white. A species of bird moves into the area and can only see the yellow moths. After 10 years 95% of the moths are white.
B. An herbicide resistant weed appears in a corn field, after 10 generations, all of the weeds are herbicide resistant.