htt/www.cucdecom.cn中国高校课件下载中心 metabolism; for example, in plants, respiration may proceed faster than photosynthesis, leading to death, however, the most frequent effect of high temperature on organism is dehydration. All terrestrial organism must conserve water but at high temperatures rates of water loss can be lethal There are large differences between the low temperature tolerances of differing species, associated with the processes of freezing, chilling and hardening Many are killed by temperatures below Ic due to the damaging effects of ice-crystal formation within cells 温度阈 高温可能导致酶失活或代谢组分不平衡,例如植物的呼吸作用快于光合作用而导致死亡。然 而高温对生物最普遍的影响是引起脱水。所有陆生生物必须保持水,但在高温下失水率能够 成为致死因子。 不同物种对低温的耐受性有很大的差异,这与结冰、寒冷和坚硬的过程有关。温度低于-1℃ 时很多物种被冻死,这是由于细胞内冰晶形成的损伤效应 生物对低温的适应 植物 形态结构:油脂、鳞片、短小、匍匐状,厚皮 生理适应:减少细胞内的水分,增加糖类、脂肪和色素 动物 形态:阿仑规律、贝格曼规律、毛、皮结构、脂肪层 生理:基础代谢和非颤抖性产热(褐色脂肪) 行为:迁徙、冬眠、冬睡、滞育、集群、活动位置 The effects of temperature on individuals may be moderated by evolved differences. Allens rule states that endothermic animals from cold climates tend to have shorter extremities(ears and legs) compared with animals from warmer climates, thus reducing their surface area: volume ratio. This ule has widespread applicability 阿伦法则 阿伦法则(Alen' s rule)陈述了来自冷气候中的内温动物与来自温暖气候的内温动物相比, 趋向于具有更短的末端(耳朵和四肢);因此降低了它们的表面积对体积的比率。 Bergmann's rule states that mammals tend to be larger in colder areas than warm climates, again to reduce their surface area: volume ratio 贝格曼规律 贝格曼规律( Bergmann' s rule)讲述了寒冷地区的哺乳动物比温暖地区的哺乳动物个体趋向 于更大,也减低了它们的表面积与体积的比率。 生物对高温的适应 植物 形态适应:叶片毛、鳞片、颜色、排列木栓层 生理适应:细胞含水量(糖/盐浓度、代谢强度)旺盛的蒸腾作用 动物 生理适应:适当放松恒温性 行为适应:栖居地点、活动时间 本章小结 光照和温度的时空变化规律 光质、光强、光周期对生物的影响 生物对光质、光强、光周期的适应
http://www.cucdc.com.cn 中国高校课件下载中心 metabolism; for example, in plants, respiration may proceed faster than photosynthesis, leading to death, however, the most frequent effect of high temperature on organism is dehydration. All terrestrial organism must conserve water but at high temperatures rates of water loss can be lethal. There are large differences between the low temperature tolerances of differing species, associated with the processes of freezing, chilling and hardening. Many are killed by temperatures below –1℃ due to the damaging effects of ice-crystal formation within cells. 温 度 阈 高温可能导致酶失活或代谢组分不平衡，例如植物的呼吸作用快于光合作用而导致死亡。然 而高温对生物最普遍的影响是引起脱水。所有陆生生物必须保持水，但在高温下失水率能够 成为致死因子。 不同物种对低温的耐受性有很大的差异，这与结冰、寒冷和坚硬的过程有关。温度低于-1℃ 时很多物种被冻死，这是由于细胞内冰晶形成的损伤效应 生物对低温的适应 植物 形态结构：油脂、鳞片、短小、匍匐状，厚皮 生理适应：减少细胞内的水分，增加糖类、脂肪和色素 动物 形态：阿仑规律、贝格曼规律、毛、皮结构、脂肪层 生理：基础代谢和非颤抖性产热(褐色脂肪)， 行为：迁徙、冬眠、冬睡、滞育、集群、活动位置 Allen’s rule The effects of temperature on individuals may be moderated by evolved differences. Allen’s rule states that endothermic animals from cold climates tend to have shorter extremities (ears and legs) compared with animals from warmer climates, thus reducing their surface area: volume ratio. This rule has widespread applicability. 阿伦法则 阿伦法则（Allen’s rule）陈述了来自冷气候中的内温动物与来自温暖气候的内温动物相比， 趋向于具有更短的末端（耳朵和四肢）；因此降低了它们的表面积对体积的比率。 Bergmann’s rule states that mammals tend to be larger in colder areas than warm climates, again to reduce their surface area: volume ratio.. 贝格曼规律 贝格曼规律（Bergmann’s rule）讲述了寒冷地区的哺乳动物比温暖地区的哺乳动物个体趋向 于更大，也减低了它们的表面积与体积的比率。 生物对高温的适应 植物 形态适应：叶片毛、鳞片、颜色、排列 木栓层 生理适应：细胞含水量(糖/盐浓度、代谢强度) 旺盛的蒸腾作用 动物 生理适应：适当放松恒温性 行为适应：栖居地点、活动时间 本 章 小 结 光照和温度的时空变化规律 光质、光强、光周期对生物的影响 生物对光质、光强、光周期的适应
htt/www.cucdecom.cn中国高校课件下载中心 温度的生态作用,极端温度对生物的影响 生物对极端低温、极端高温的影响 主要概念 春化、光饱和点、光补偿点、阴地植物、阳地植物、长日照植物、短日照植物、长日照 动物、短日照动物、温度三基点、有效积温、贝格曼规律、阿仑规律、休眠 思考题 1.光在时空上的配置对植物和动物产生哪些影响?它们又是如何适应这些变化的? 2.低温和高温对生物会产生哪些影响?为什么温度能够限制生物的分布 3.生物是如何适应极端温度条件的? 4.在引种驯化中应该注意光照和温度的哪些因素? 六、 Organism and Water (一)水因子的生态作用 1、水是生物生存的重要条件 2、水对动植物生长发育的影响 3、水对动植物数量和分布的影响 生物体的水分获得与损失途径 水分的丧失途径 植物一蒸发(蒸腾作用、扩散作用)失水,分泌失水。 动物一蒸发失水,排泄、分泌失水 水分获得途径 植物一一根部吸收,叶面吸收 动物一一食物,体表吸收,代谢水。 (二)生物对水因子的适应 1、植物对水因子的适应 陆生植物:湿生植物、中生植物、旱生植物(少浆液、多浆液植物) 水生植物:沉水植物、浮水植物、挺水植物 在形态、生理、结构上的不同适应 2、动物对水因子的适应 水生动物的渗透压调节 两栖类动物对环境湿度的适应 陆生动物对环境湿度的适应 Soil water For terrestrial plants the main source of water is the soil, which serves as a reservoir, water enters the reservoir as rain or melting snow and passes into the soil pores. The upper limit of the water-holding capacity of a soil is called the field capacity: This is the amount of water which can be held by soil pores against the force of gravity Plants cannot extract all the water held in the soil, as they cannot exert sufficient suction force to extract water from the narrower soil pores. The lower limit of water availability is thus determined by the physiology of the plant species and is known as the permanent wilting point- the soil water content at which plants wilt and are unable to recover 土壤水 对于陆地植物,水的主要来源是土壤,它起了蓄水池的作用。当下雨或雪融化时,水进入蓄 水池,并流进孔隙。土壤的水容量上限称为田间持水量( field cap-acity)。这是土壤孔隙抗 地心引力所储蓄的水量
http://www.cucdc.com.cn 中国高校课件下载中心 温度的生态作用，极端温度对生物的影响 生物对极端低温、极端高温的影响 主要概念 春化、光饱和点、光补偿点、阴地植物、阳地植物、长日照植物、短日照植物、长日照 动物、短日照动物、温度三基点、有效积温、贝格曼规律、阿仑规律、休眠 思考题 1. 光在时空上的配置对植物和动物产生哪些影响？它们又是如何适应这些变化的？ 2. 低温和高温对生物会产生哪些影响?为什么温度能够限制生物的分布? 3. 生物是如何适应极端温度条件的？ 4. 在引种驯化中应该注意光照和温度的哪些因素？ 六、Organism and Water （一）水因子的生态作用 1、水是生物生存的重要条件 2、水对动植物生长发育的影响 3、水对动植物数量和分布的影响 生物体的水分获得与损失途径 水分的丧失途径 植物－蒸发（蒸腾作用、扩散作用）失水，分泌失水。 动物－蒸发失水，排泄、分泌失水。 水分获得途径 植物－－根部吸收，叶面吸收。 动物－－食物，体表吸收，代谢水。 （二）生物对水因子的适应 1、植物对水因子的适应 陆生植物： 湿生植物、中生植物、旱生植物（少浆液、多浆液植物） 水生植物：沉水植物、浮水植物、挺水植物 在形态、生理、结构上的不同适应 2、动物对水因子的适应 水生动物的渗透压调节 两栖类动物对环境湿度的适应 陆生动物对环境湿度的适应 Soil water For terrestrial plants the main source of water is the soil, which serves as a reservoir., water enters the reservoir as rain or melting snow and passes into the soil pores. The upper limit of the water-holding capacity of a soil is called the field capacity. This is the amount of water which can be held by soil pores against the force of gravity. Plants cannot extract all the water held in the soil, as they cannot exert sufficient suction force to extract water from the narrower soil pores. The lower limit of water availability is thus determined by the physiology of the plant species and is known as the permanent wilting point – the soil water content at which plants wilt and are unable to recover. 土 壤 水 对于陆地植物，水的主要来源是土壤，它起了蓄水池的作用。当下雨或雪融化时，水进入蓄 水池，并流进孔隙。土壤的水容量上限称为田间持水量（field cap-acity）。这是土壤孔隙抗 地心引力所储蓄的水量
htt/www.cucdecom.cn中国高校课件下载中心 植物不能吸取土壤中储蓄的全部水,因为它们不能产生足够的吸力从更细的土壤孔隙中吸 水。因此可利用水的下限是由植物物种的生理特性所决定的,被称为永久萎蔫点( permanent wilting point)—土壤水( soil water)含量在这个点上,植物枯死,不能恢复。 The uptake of water by roots Roots can capture water from the soil in two ways: either water may move through the soil towards a root or the root may grow through the soil towards the water. As a root withdraws water from the soil capillary pores at its surface, it creates water depletion zones around it. If a root draws water from the soil very rapidly, the resource depletion zone(EDz) will receive water from the surrounding soil at a slow rate, restricting water availability, so plants may wilt even in soil containing abundant water. 根对水的吸收 根以两种方式从土壤中捕获水:要么水穿过土壤向根移动,要么根生长穿过土壤向水移动。 当根以它的表面从土壤毛细管孔隙吸水时,在根的周围产生了水耗竭区。如果根从土壤中吸 水很快,资源耗竭区(RDZ)将以一个低速率从周围土壤中接收水,从而限制了水的可利用 性,使植物即使在含水丰富的土壤中也可能枯萎 Aquatic plants and water Water is apparently available in aquatic environments. However, the osmotic regulation of internal fluids can be energetically expensive, especially in saline environments. The salinity of an aquatic environment and of terrestrial habitats bordering the sea has an important influence on plant distribution and abundance. Plants which grow in high salini electrolytes in their vacuoles, but the concentration in the cytoplasm and organelles is kept low 水生植物和水 在水环境中,水显然是随意可利用的。然而,内部体液的渗透压调节可能消耗能量,特别是 在盐水环境中。水环境的盐度与沿海陆地栖息地的盐度,对植物分布移度有重要的影响。生 长在高盐度中的植物,即盐生植物,它们的液泡中累积了电解质,但在细胞质和细胞器官中 保持着低浓度。 Water availability and plant productivity Precipitation is a key determinant of plant productivity in forests, whilst in arid regions there is an approximately linear increase in primary productivity with increasing precipitation. The amount of water that would be transpired from a site, assuming no soil water limitation and complete vegetation cover is the potential evapotranspiration rate. The difference between this index and th precipitation rate defines whether the environment is moist or arid 水的可利用性与植物生产力 降雨量是森林植物生产量的关键决定因子,而在干旱地区,初级生产量随降雨量的增加大致 呈一个线形增长。假设一个地区没有土壤的水限制,并完全地被植物覆盖,水从这个地区的 蒸发量就是潜在蒸发蒸腾速度( potential evapotranspiration rate)。这个指标和降雨量之间的 差异决定了环境是潮湿的,还是干旱的。 Water balance in fish Maintaining water balance is problematic in an aquatic environment, which is countered by osmoregulatory mechanisms. Freshwater fish have to continually excrete excess water because the fish is hypertonic relative to its surroundings( the concentration of solutes in body fluids is higher than the solute concentration of the water), and they produce a large volume of very dilute urine Bony fishes living in seawater have the opposite problem, being hypotonic to their surroundings The kidneys of marine fish secrete very little urine, and instead function mainly as a means of
http://www.cucdc.com.cn 中国高校课件下载中心 植物不能吸取土壤中储蓄的全部水，因为它们不能产生足够的吸力从更细的土壤孔隙中吸 水。因此可利用水的下限是由植物物种的生理特性所决定的，被称为永久萎蔫点（permanent wilting point）——土壤水（soil water）含量在这个点上，植物枯死，不能恢复。 The uptake of water by roots Roots can capture water from the soil in two ways: either water may move through the soil towards a root or the root may grow through the soil towards the water. As a root withdraws water from the soil capillary pores at its surface, it creates water depletion zones around it. If a root draws water from the soil very rapidly, the resource depletion zone (EDZ) will receive water from the surrounding soil at a slow rate, restricting water availability, so plants may wilt even in soil containing abundant water. 根对水的吸收 根以两种方式从土壤中捕获水：要么水穿过土壤向根移动，要么根生长穿过土壤向水移动。 当根以它的表面从土壤毛细管孔隙吸水时，在根的周围产生了水耗竭区。如果根从土壤中吸 水很快，资源耗竭区（RDZ）将以一个低速率从周围土壤中接收水，从而限制了水的可利用 性，使植物即使在含水丰富的土壤中也可能枯萎。 Aquatic plants and water Water is apparently available in aquatic environments. However, the osmotic regulation of internal fluids can be energetically expensive, especially in saline environments. The salinity of an aquatic environment and of terrestrial habitats bordering the sea has an important influence on plant distribution and abundance. Plants which grow in high salinity, halophytes, accumulate electrolytes in their vacuoles, but the concentration in the cytoplasm and organelles is kept low. 水生植物和水 在水环境中，水显然是随意可利用的。然而，内部体液的渗透压调节可能消耗能量，特别是 在盐水环境中。水环境的盐度与沿海陆地栖息地的盐度，对植物分布移度有重要的影响。生 长在高盐度中的植物，即盐生植物，它们的液泡中累积了电解质，但在细胞质和细胞器官中 保持着低浓度。 Water availability and plant productivity Precipitation is a key determinant of plant productivity in forests, whilst in arid regions there is an approximately linear increase in primary productivity with increasing precipitation. The amount of water that would be transpired from a site, assuming no soil water limitation and complete vegetation cover is the potential evapotranspiration rate. The difference between this index and the precipitation rate defines whether the environment is moist or arid. 水的可利用性与植物生产力 降雨量是森林植物生产量的关键决定因子，而在干旱地区，初级生产量随降雨量的增加大致 呈一个线形增长。假设一个地区没有土壤的水限制，并完全地被植物覆盖，水从这个地区的 蒸发量就是潜在蒸发蒸腾速度（potential evapotranspiration rate）。这个指标和降雨量之间的 差异决定了环境是潮湿的，还是干旱的。 Water balance in fish Maintaining water balance is problematic in an aquatic environment, which is countered by osmoregulatory mechanisms. Freshwater fish have to continually excrete excess water because the fish is hypertonic relative to its surroundings (the concentration of solutes in body fluids is higher than the solute concentration of the water), and they produce a large volume of very dilute urine. Bony fishes living in seawater have the opposite problem, being hypotonic to their surroundings. The kidneys of marine fish secrete very little urine, and instead function mainly as a means of
htt/www.cucdecom.cn中国高校课件下载中心 removal of divalent ions such as Ca2+ Mg2+and So42 鱼类的水平衡 在水环境中保持水平衡是有疑问的,它是通过渗透调节机制解决的。淡水鱼必须连续地排泄 过量的水,因为鱼与它的环境相比,它是高渗透性的(体液的溶质浓度比水的溶质浓度高), 它们产生大量的低浓度的尿 生活在海水中的硬骨鱼有相反的问题,它们要的功能是去除两价的离子,如像Ca2+、Mg2+ 和S 等渗( Isosmotic organism) 体内和体外的渗透压相等,水和盐以大致相等的速度在体内外之间扩散。仅排泄失水 通过食物、饮水、代谢水获得水,泌盐器官排出多余的盐分 高渗( hyperosmotic organism) 体内的渗透压高于体外,水由环境中向体内扩散,体内的盐分向外扩散。通过排泄作用 排出多余的水,盐分通过食物和组织摄入 低渗( hypoosmotic organism) 体内渗透压低于体外,水分向外扩散,盐分进入体内。通过食物、代谢水和饮水获得水, 多种多样的泌盐组织排出多余的盐分 淡水鱼类 生活的环境是一种特殊的低盐环境,淡水硬骨鱼类血液和体液的滲透压高于水的渗透压,进 入体内多余的水通过鱼的肾脏排除大量低浓度尿,通过食物和鳃主动吸收盐离子,保持水盐 代谢的平衡。 海洋硬骨鱼类 的血液和体液大大低于海水的渗透浓度,如鲱、鲑等。因此保持水分平衡的有效方法是大量 饮水:通过细胞膜上具有Na+泵和K+泵,主动排盐 Water balance in amphibians Amphibian kidneys function much like those of freshwater fishes. However, on land, where dehydration is the most important problem in terms of osmoregulation, frogs conserve body fluid by reabsorbing water across the epithelium of the urinary bladder 两栖类的水平衡 两栖类的肾功能很像淡水鱼的肾功能。然而在陆地上,脱水对渗透调节是最重要的问题,蛙 保存体液是通过膀胱上皮细胞的重吸收水。 Water conservation by terrestrial animals A major problem faced by terrestrial organisms is the loss of a continuous supply of water necessary to keep tissue surfaces moist. When air is inhaled, it passes along the respiratory tract into the lungs, where it is in contact with the moist respiratory tissues. If the moist air was exhaled, water would be lost The recovery of respiratory moisture by most terrestrial animals involves countercurrent exchange Exhaled air from the lungs encounters a countercurment-like gradient on the way out. This interaction between the departing air and the respiratory surfaces results in an efficient return of moisture to the tissues 陆生动物的水保持 陆生动物面对的主要问题是连续地失水,这是供应到组织表面维持潮湿所必需的水。当空气 被吸入时,它沿着呼吸道进入肺,和潮湿的呼吸组织相接触。如果潮湿的空气被呼出,水就 会丢失 大多数陆生动物呼吸湿度的维持包括了逆流交换( countercurrent exchange)从肺呼出的气体
http://www.cucdc.com.cn 中国高校课件下载中心 removal of divalent ions such as Ca2+,Mg2+and SO42-. 鱼类的水平衡 在水环境中保持水平衡是有疑问的，它是通过渗透调节机制解决的。淡水鱼必须连续地排泄 过量的水，因为鱼与它的环境相比，它是高渗透性的（体液的溶质浓度比水的溶质浓度高）， 它们产生大量的低浓度的尿。 生活在海水中的硬骨鱼有相反的问题，它们要的功能是去除两价的离子，如像 Ca 2+、Mg 2+ 和 SO42- 等渗（isosmotic organism） 体内和体外的渗透压相等，水和盐以大致相等的速度在体内外之间扩散。仅排泄失水， 通过食物、饮水、代谢水获得水，泌盐器官排出多余的盐分。 高渗（hyperosmotic organism） 体内的渗透压高于体外，水由环境中向体内扩散，体内的盐分向外扩散。通过排泄作用 排出多余的水，盐分通过食物和组织摄入。 低渗（hypoosmotic organism） 体内渗透压低于体外，水分向外扩散，盐分进入体内。通过食物、代谢水和饮水获得水， 多种多样的泌盐组织排出多余的盐分。 淡水鱼类 生活的环境是一种特殊的低盐环境，淡水硬骨鱼类血液和体液的渗透压高于水的渗透压，进 入体内多余的水通过鱼的肾脏排除大量低浓度尿，通过食物和鳃主动吸收盐离子，保持水盐 代谢的平衡。 海洋硬骨鱼类 的血液和体液大大低于海水的渗透浓度，如鲱、鲑等。因此保持水分平衡的有效方法是大量 饮水；通过细胞膜上具有 Na+泵和 K+泵，主动排盐。 Water balance in amphibians Amphibian kidneys function much like those of freshwater fishes.However, on land,where dehydration is the most important problem in terms of osmoregulation, frogs conserve body fluid by reabsorbing water across the epithelium of the urinary bladder. 两栖类的水平衡 两栖类的肾功能很像淡水鱼的肾功能。然而在陆地上，脱水对渗透调节是最重要的问题，蛙 保存体液是通过膀胱上皮细胞的重吸收水。 Water conservation by terrestrial animals A major problem faced by terrestrial organisms is the loss of a continuous supply of water necessary to keep tissue surfaces moist.When air is inhaled,it passes along the respiratory tract into the lungs,where it is in contact with the moist respiratory tissues.If the moist air was exhaled, water would be lost. The recovery of respiratory moisture by most terrestrial animals involves countercurrent exchange. Exhaled air from the lungs encounters a countercurrent-like gradient on the way out. This interaction between the departing air and the respiratory surfaces results in an efficient return of moisture to the tissues. 陆生动物的水保持 陆生动物面对的主要问题是连续地失水，这是供应到组织表面维持潮湿所必需的水。当空气 被吸入时，它沿着呼吸道进入肺，和潮湿的呼吸组织相接触。如果潮湿的空气被呼出，水就 会丢失。 大多数陆生动物呼吸湿度的维持包括了逆流交换（countercurrent exchange）从肺呼出的气体
htt/www.cucdecom.cn中国高校课件下载中心 在呼出的通道上有一个像逆流的梯度。呼出的气体和呼吸表面的相互作用,导致水分有效地 返回组织。 Water conservation by mammalian kidneys The water-conserving ability of the mammalian kidney represents a key terrestrial adaptation Water recovery from the urine before it leaves the kidney takes place in the loop of Henle Mammals adapted to the desert (such as kangaroo rats) that excrete highly concentrated hypertonic urine, have exceptionally long loops of Henle. In contrast, beavers, which spend much of their time in fresh water, have nephrons with veryshort loops, resulting in dilute urine. The kidneys of reptiles are less sophisticated and produce urine that is, at best, isotonic to body fluid This means that the solute concentration of urine is equal to the solute concentration of the body fluids 哺乳动物肾脏的水保持 哺乳动物肾脏的水保存能力表现出关键的陆生适应性。尿离开肾脏之前,水在亨利氏袢中被 回收 适应于荒漠的哺乳动物,如更格卢鼠,排泄高浓度的高渗尿,它们有极长的亨利氏袢。相反, 河狸大部分时间是在淡水中渡过的,它们的肾单位具有很短的袢,产生低浓度的尿。爬行动 物的肾脏结构较简单,产生的尿最多也就是与体液等渗。这意味着,尿的溶质浓度与体液的 溶质浓度是相等的。 形态结构适应 昆虫具有几丁质的体壁,防止水分的过量蒸发;两栖类动物体表分泌粘液以保持湿润: 哺乳动物有皮质腺和毛,防止体内水分过多蒸发 行为的适应 沙漠动物昼伏夜出:沙漠地区夏季昼夜地表温度相差很大,因此地面和地下的相对湿度 和蒸发力相差很大 迁徙:在水分和食物不足时,迁移到别处 POPULATIONS AND POPULATION STRUCTURE Population ns of the same species which occupies a given area. The boundaries between populations can be arbitrary. 种群 种群是一定区域内同种生物个体的集合。种群间的边界可以是任意的 自然种群的基本特征 空间特征:种群具有一定的分布区域 数量特征:每单位面积(或空间)上的个体数量(即密度)及变动 遗传特征:种群具有一定的基因组成 个体可能呈随机、均匀和聚集分布格局(方差严平均数比) 均匀分布:S2/m=0-原因:种群内个体间的竞争。 随机分布:S2/m=1-原因:资源分布均匀,种群内个体间没有彼此吸引或排斥 聚集分布:S2/m>1-原因:资源分布不均匀:种子植物以母株为扩散中心;动物的社会行为 使其结群 方差/平均数比率 S2=2(fx)2-C2fx)2n]/n-1) m=∑fx/n 样方中某种个体数
http://www.cucdc.com.cn 中国高校课件下载中心 在呼出的通道上有一个像逆流的梯度。呼出的气体和呼吸表面的相互作用，导致水分有效地 返回组织。 Water conservation by mammalian kidneys The water-conserving ability of the mammalian kidney represents a key terrestrial adaptation. Water recovery from the urine before it leaves the kidney takes place in the loop of Henle. Mammals adapted to the desert (such as kangaroo rats) that excrete highly concentrated hypertonic urine, have exceptionally long loops of Henle. In contrast, beavers, which spend much of their time in fresh water, have nephrons with very’short loops, resulting in dilute urine. The kidneys of reptiles are less sophisticated and produce urine that is, at best, isotonic to body fluids. This means that the solute concentration of urine is equal to the solute concentration of the body fluids. 哺乳动物肾脏的水保持 哺乳动物肾脏的水保存能力表现出关键的陆生适应性。尿离开肾脏之前，水在亨利氏袢中被 回收。 适应于荒漠的哺乳动物，如更格卢鼠，排泄高浓度的高渗尿，它们有极长的亨利氏袢。相反， 河狸大部分时间是在淡水中渡过的，它们的肾单位具有很短的袢，产生低浓度的尿。爬行动 物的肾脏结构较简单，产生的尿最多也就是与体液等渗。这意味着，尿的溶质浓度与体液的 溶质浓度是相等的。 形态结构适应 昆虫具有几丁质的体壁，防止水分的过量蒸发；两栖类动物体表分泌粘液以保持湿润； 哺乳动物有皮质腺和毛，防止体内水分过多蒸发。 行为的适应 沙漠动物昼伏夜出：沙漠地区夏季昼夜地表温度相差很大，因此地面和地下的相对湿度 和蒸发力相差很大 迁徙：在水分和食物不足时，迁移到别处。 POPULATIONS AND POPULATION STRUCTURE Population A population is a group of organisms of the same species which occupies a given area. The boundaries between populations can be arbitrary. 种 群 种群是一定区域内同种生物个体的集合。种群间的边界可以是任意的。 自然种群的基本特征 空间特征：种群具有一定的分布区域 数量特征：每单位面积(或空间)上的个体数量(即密度)及变动 遗传特征：种群具有一定的基因组成 个体可能呈随机、均匀和聚集分布格局 (方差/平均数比) 均匀分布：S2/m=0--原因：种群内个体间的竞争。 随机分布：S2/m=1--原因：资源分布均匀，种群内个体间没有彼此吸引或排斥。 聚集分布：S2/m>1--原因：资源分布不均匀；种子植物以母株为扩散中心；动物的社会行为 使其结群。 方差/平均数比率：S2/m S2=[Σ(fx)2-(Σfx)2/n]/(n-1) m=Σfx/n x—样方中某种个体数