Question

read this passage about a variable inherited trait in fruit flies.
fruit flies are insects that live in many parts of the world. fruit flies often need to fly to find resources and avoid predators.
a fruit fly’s wing width affects how well it flies at different temperatures. flies with smaller wing widths can fly better when it is hot. flies with larger wing widths can fly better when it is cold.
the average temperature in the fruit flies’ environment decreased. after this change, over a time period long enough for natural selection to occur, the average wing width increased in the fruit fly population.
use the theory of natural selection to construct a possible explanation for how the fruit fly population adapted to its changed environment.
having a smaller wing width was advantageous than having a larger wing width after the environment changed. so the alleles contributing to larger wing widths were passed on with frequency than the alleles contributing to smaller wing widths. as a result, flies with larger wing widths became common. over time, the population adapted such that the average wing width moved a size best suited for flying at colder temperatures.

Explanation:

1. First blank: The environment temperature decreased, so larger wing width is more advantageous (flies with larger wings fly better in cold). So smaller wing width is "less" advantageous.
2. Second blank: Alleles for larger wings are passed on more, so "higher" frequency.
3. Third blank: Larger wing width flies become more common, so "more" common.
4. Fourth blank: Average wing width moves to a size (larger) suited for cold, so "toward".

Answer:

1. less
2. higher
3. more
4. toward