Biologist:
Some speculate that the unusually high frequency of small goats found in island populations is a response to evolutionary pressure to increase the number of goats so as to ensure a diverse gene pool. However, only the reproductive success of a trait influences its frequency in a population. So, the only kind of evolutionary pressure that can reduce the average size of the members of a goat population is that resulting from small goats achieving greater reproductive success than their larger cousins.
to increase the number of goats 修饰哪一个？
so as to ensure a diverse gene pool是不是to increase的目的状语。
that是什么意思，替代pressure？
achieving是做small goats的定语，还是result from的动名词宾语？？ | 
