生态学_生态学.pptVIP

I2 种内竞争 要 点 密度制约 密度制约描述适合度与种群大小之间的关系。种群调节的一个关键因子是负的密度制约，当种群密度增加时，由于种内竞争，使适合度下降。 I2 INTRASPECIFIC COMPETITION Density dependence describes the relationship between fitness and population size. A key population regulatory factor is negative density dependence, where declining fitness occurs as population density increases within a species due to intraspecific competition. Key Notes Density dependence 扩 散 生物可通过扩散离开种群密度高的地区，来对高水平的种内竞争做出反应。即使在生活周期内大部分时间营固着生活的种类，也有一个可运动的扩散期。扩散通常由种群内较年轻的个体进行，而在许多哺乳动物中雄性比雌性扩散更多。 领 域 性 许多动物种（包括昆虫、鸟类和哺乳动物）的个体或群体为争夺空间而竞争。保持领域边界的个体间有积极的相互干扰行为。领域使其所有者受益，为对抗入侵者，保护领域所付出的代价，被增加的食物供应、提高的交配成功率和降低的被捕食的危险所带来的价值超过。 Organisms can respond to high levels of intraspecific competition by dispersing away from the area of high population.density. Even in species that are sessile for most of the lifecycle, there is a mobile dispersal stage. Dispersal is often undertaken by the younger members of a population, whilst in many mammal species males disperse more than females to Dispersal In many animal species (including insects, birds and mammals) individuals or groups compete for areas of space. There is active interference between individuals to maintain the territory boundaries. Territoriality gives a benefit to the territory-holder, such that the costs of defending the territory against intruders are outweighed by advantages such as in creased food supplies, increased mating success and reduced predation risk. Territoriality 自 疏 固着生长的生物，包括植物，不能通过运动逃避竞争，因此竞争中的失败者死去在同样年龄大小的植物群中，这种竞争结果使较少量的较大个体存活下来。这一过程叫做“自疏”。自疏导致密度与植物个体大小之间的关系，这在双对数作图时呈现典型的-3/2斜率。这种关系叫做Yoda-3/2自疏法则。 相关主题 生态位（B3） 竞争的性质（I1）密度和密度制约（H3） 资源分配（I3） Related topics The niche (B3) The mature of competition (I1) Density and density dependence (H3) Resource partitioning (I3) Sessile organisms, including plants, cannot escape competition by movement, and therefore the losers in the competi