htt/www.cucdecom.cn中国高校课件下载中心 成为该生物限制因子 限制因子定律( Law of limiting factor) 生态因子处于低于生物正常生长所需的最小量和高于生物正常生长所需的最大量时,都对 生物具有限制性影响( Blackman,1905 该定律的应用价值-掌握研究生物与环境复杂关系的钥匙 Environmental variation Most organisms have to cope with a continually changing external environment over a range of timescales. Some environmental factors may change over seconds or minutes(e.g sunlight intensity when there is patchy cloud) whilst others may change daily or seasonally or over a much change daily or seasonally or over a much longer period(e.g. glaciation cycles) 环境变异 大多数有机体都必须应付在一定时间尺度范围内不断变化着的外界环境。某些环境因子的变 化以秒或分计(如当有云块时的阳光强度),另一些因子的变化以日或季计,甚至更长更长 的时期(如冰河周期)。 Organisms can cope with variation in their external environment(though different species may differ markedly ) The upper and lower extremes of species limits of tolerance. Usually, growth will not occur at these extremes but in a narrower range of conditions, and fitness will be greatest only for a yet narrower optimal range 耐受性 有机体能够应付其外部环境的变化(虽然不同物质表现很不相同)。种的成员能够生存的环 境条件上限和下限是种的耐受限度。在此极端条件下通常不出现生长,但在条件更狭窄的范 围内能生长,而适合度最大只能出现在更窄的最适范围内 生物对不同生态因子的耐受范围不同,不同年龄、季节、栖息地等同种生物对生态因子的耐 受性不同 对很多生态因子耐受范围都很宽的生物,其分布区一般很广 个体发育的不同阶段,对生态因子的耐受限度不同 不同的生物种,对同一生态因子的耐受性不同 某一生态因子处于非最适状态下时,生物对其他生态因子的耐受限度也下降 Homeostasis The maintenance of a relatively constant internal environment by an organism in a variable external environment is called homeostasis, All organisms adopt a degree of homeostatic control but, as true, large organisms are more decoupled from their external environment than small ones 稳态 有机体在可变动的外部环境中维持一个相对恒定的内部环境,称为稳态( homeostasis) 切有机体都采取一定程度的稳态控制,但是一般地说,大型有机体比小型的更易从其外部环 境中退耦( decouple)。 Negative feedback Most biological homeostatic mechanisms act in a broadly similar way: if the current internal level of a factor(e.g. temperature or osmolarity) is too high, the mechanism will reduce it; if the level is too low the mechanism will increase it. This process, by which the response is opposite to the signal, is known as negative feedback 负反馈 大多数生物的稳态机制以大致一样的方式起作用:如果一个因子的内部水平(如温度或渗透http://www.cucdc.com.cn 中国高校课件下载中心 成为该生物限制因子 限制因子定律 (Law of limiting factor) -生态因子处于低于生物正常生长所需的最小量和高于生物正常生长所需的最大量时，都对 生物具有限制性影响 (Blackman，1905) 该定律的应用价值---掌握研究生物与环境复杂关系的钥匙 Environmental variation Most organisms have to cope with a continually changing external environment over a range of timescales. Some environmental factors may change over seconds or minutes (e.g. sunlight intensity when .there is patchy cloud) whilst others may change daily or seasonally or over a much change daily or seasonally or over a much longer period (e.g. glaciation cycles). 环境变异 大多数有机体都必须应付在一定时间尺度范围内不断变化着的外界环境。某些环境因子的变 化以秒或分计（如当有云块时的阳光强度），另一些因子的变化以日或季计，甚至更长更长 的时期（如冰河周期）。 tolerance Organisms can cope with variation in their external environment (though different species may differ markedly). The upper and lower extremes of species limits of tolerance. Usually, growth will not occur at these extremes but in a narrower range of conditions, and fitness will be greatest only for a yet narrower optimal range. 耐受性 有机体能够应付其外部环境的变化（虽然不同物质表现很不相同）。种的成员能够生存的环 境条件上限和下限是种的耐受限度。在此极端条件下通常不出现生长，但在条件更狭窄的范 围内能生长，而适合度最大只能出现在更窄的最适范围内。 生物对不同生态因子的耐受范围不同，不同年龄、季节、栖息地等同种生物对生态因子的耐 受性不同 -对很多生态因子耐受范围都很宽的生物，其分布区一般很广 -个体发育的不同阶段，对生态因子的耐受限度不同 -不同的生物种，对同一生态因子的耐受性不同 -某一生态因子处于非最适状态下时，生物对其他生态因子的耐受限度也下降 Homeostasis The maintenance of a relatively constant internal environment by an organism in a variable external environment is called homeostasis, All organisms adopt a degree of homeostatic control, but, as true, large organisms are more decoupled from their external environment than small ones. 稳态 有机体在可变动的外部环境中维持一个相对恒定的内部环境，称为稳态（homeostasis）。一 切有机体都采取一定程度的稳态控制，但是一般地说，大型有机体比小型的更易从其外部环 境中退耦（decouple）。 Negative feedback Most biological homeostatic mechanisms act in a broadly similar way: if the current internal level of a factor(e.g.temperature or osmolarity) is too high, the mechanism will reduce it; if the level is too low the mechanism will increase it. This process, by which the response is opposite to the signal, is known as negative feedback. 负反馈 大多数生物的稳态机制以大致一样的方式起作用：如果一个因子的内部水平（如温度或渗透