英语语法分析

Early research confirmed the role of intrasexual selection.

早期的研究证实了无性选择的作用。

In the first, male competition and intrasexual selection produce relatively short, simple songs used mainly in territorial behavior.

在第一种情况下，雄性竞争和性内选择产生相对简短的鸣声，主要用于地盘行为。