“Some species of squirrels seem to anticipate when seed yields are unusually high, reproducing at increased rates as if (to take advantage) of the coming abundance of food”
(to take advantage) isn’t suppose to be taking atvantage?
No, not necessarily. “As if” introduces a clause (not a phrase), so parallelism is not obligatory.
The most common meaningful difference between infinitives (“to + base form”) and gerunds ("-ing" nouns) is that the former are often used to indicate purpose or intent, sort of like “in order to.” The sentence you provide matches that expectation, so infinitive is preferable to gerund.
(And for style the SAT generally prefers almost any alternative to gerunds when a choice is possible.)
thank u very much