as insects became exposed to pyrethroids, toxicity of pyrethroids weakened over time. which means that Most insects had the allele for pyrethroid resistance, but it remained masked. The allele for said pyrethroid resistance, evidently increased throughout the population.
has this helped?
<span>Notice a couple of things
different between (A) and (B). It was NOT the first time a biologist
proposed that species changed through time (so it's not B). But it
finally *solidified* that idea by giving "change through time"
(evolution) a MECHANISM. It gave a plausible explanation for WHY
species change over time, in a testable way that made sense and had
evidence to support it.
So it finally dismissed the idea that species are constant.
It also emphasized that the simple presence of *variation* within a population was a key reason for evolution.
While we're at it ... (C) is wrong because it's not *individuals* that
acclimate (adapt) to their environment, but the population (the species)
as a whole.
And (D) is wrong because it had nothing to do with economics or the monarchy.</span>
