农药,寄生虫和饥饿的尾酒使蜜蜂下降并消失
相关概念视频
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
Positive Frequency-Dependent Selection
In positive...
Altruistic behaviors are “unselfish” behaviors—those that help another individual at the expense of the individual carrying out the behavior. Despite the negative consequences for the altruistic animal, these behaviors are thought to have evolved for several reasons.
Reasons for Altruistic Behaviors
First, most altruistic behavior occurs between individuals that are related. Altruism is particularly pronounced in animals that live in colonies with one reproductively capable...

