2-生命的进化与适应.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,三、生命的进化,地球生命起源于30亿年前的太古代，历经3次大爆发、4次大灭绝，从低等、简单到高等、复杂，,30亿年原核生物，,20亿年的元古代真核生物，,6亿年的古生代寒武纪无脊椎动物，,5亿年的古生代奥陶纪脊椎动物、陆生植物，,1.8亿年的中生代侏罗纪原始哺乳类，,300万年的新生代更新世猿人，,多细胞生物后的演化：,两个特点：一是个体结构与机能的进化，一是新物种的形成，由水生向陆生发展构成生态系统。,结构的进化：,5.4亿年前:植物骨骼化，出现钙藻；,4.3亿年前:植物木质化维管系统形成，陆生维管植物诞生,被子植物起源；,3.4亿年前:动物躯体功能分化、保护支持系统出现，高级无脊椎动物诞生；呼吸系统形成、外骨骼特化，陆生节肢动物出现,3.9亿年前:中枢神经系统集中、内骨骼形成，鱼类起源，呼吸系统发展、两栖类起源；,3.4亿年前:生殖系统进化（羊膜卵），陆生爬行动物出现；,2.1亿年前:体温调节发展温血动物出现；生殖方式进化、哺乳动物起源；,1.9亿年前:鸟类进化,有性生殖：有性生殖在高等生物是一种普遍存在的繁殖方式，与其相关的第二性征的分化、求偶行为、社会等级体系、情感的交流等构成了当今生物多样性的重要内涵，但起源尚不清楚。,SECRET LOVERS?,Giardia,Bares All:Parasite genes reveal long sexual history,While it hasnt yet been caught in the act,a single-celled parasite has been ready for sex for billions of years.,A new research finding provides evidence that sexual reproduction started as soon as life forms that have nuclei and organelles within their cells branched off from their structurally simpler ancestors.,The parasite,Giardia intestinalis,is well known for causing a diarrheal disease that animals and people contract after drinking contaminated water.,Many researchers consider this species to be one of the most ancient living members of the eukaryote,or true nucleus,lineage.,However,unlike most eukaryotes,G.,intestinalis,and its relatives have been long considered to reproduce only asexuallyby division into two identical cells.,On the other hand,the findings suggest that meiosis was established early in eukaryotic evolution,making sexual reproduction a very central feature of being a eukaryote,Establishing that all eukaryotes are capable of meiosis could make the evolutionary transition from prokaryote to eukaryote even more difficult to sort out.,A lot had to happen when eukaryotes evolved.Why arent there any intermediate stages of this process alive today?Did all the intermediate forms go extinct,and why?Roger asks.,对生命的起源至今仍为两种认识：,神创论和自然产生论，后者认为生命如同其他物质有产生和发展的历程，进化论的提出提供了有力支持。,对生物进化的新认识：,前面我们对生命诞生过程的分析是从多种途径综合得到的结果，但当对同一生物的研究结果进行比较时就需要一个可以比较的平台才能得出正确的结论，否则就会出现争论。,自然选择：作用于表现型而非基因型，用生存力表示动物的适应性。,现代综合论：,20世纪遗传学的建立和发展使人们认识到有性繁殖过程中的基因交流和重组，对遗传和变异有着深刻的影响，自然选择的发生也要更加复杂。对进化的解释从选择个体转变到了种群，因为在一个大种群里基因的分布基因频率是稳定不变的，既没有新种产生的可能，只有在突变基因达到一定比例后才会不同于以前的物种，经过对达尔文主义修正后的理论称为现代综合论，,由于引进了基因交流和重组的概念，它很好的解释了小进化问题，如环境变化后基因频率将随之偏移，并出现相应的表型；基因的杂和状态使纯合致死的基因表留下来，并可能具有较高的适应力；,小种群基因频率的差异可以导致新种的诞生。现代综合论强调了基因突变的贡献，使生物适应环境的进程中由完全被动的选择转移到了自身具有进化的力量，选择达到的是一种基因平衡。,新挑战：,现代综合论很好的说明了小进化，但大进化的过程却表现的是跳跃式进程和进化停滞，而且与环境的变化不总一致，表明生物进化理论需要有新的发展。其一是，突变存在着方向性，而非随机性，且来自生物本身；其二，生物发育过程中调节机制的突变可以诱发生命结构的巨大变化；其三：生命进化的过程可以看作是一个复杂的动力学系统，从混沌向温态发展，分子生物学的发展也将对生物进化做出贡献。,对进化现象的新理解及研究途径：,对物种概念的解释中生殖隔离问题，从化石资料无法获得证据，而在分类学中物种是没有时间因素的，无法得出在一段时间内一个群体是否属于同一物种的结论，这就与生物进化的时向性产生了矛盾。为了解决问题，人们提出了新的方法：把生物的形态特征进行分类，将具有高级特征的物种首先归为一类，如蝙蝠和马与鸟，胎生哺乳比有翅高等。这样在进化研究中加入了时间的因素，物种的概念就失去了生殖隔离的内容。,生物进化谱系的建立：,根据进化物种的概念把历史上不同阶段出现的生物演进的亲缘关系构筑出一幅图画，又称进化树，但仍留有争议的地方，如对鸟类的起源，同时也表明单纯使用形态分类的局限。,大进化与小进化：,大进化研究物种或更高级分类单元的规模演变特性和规律，发现生物的进化有三种主要方式：,辐射进化（出现岐化，适应各自的生存环境）、趋同进化（不同物种间的结构机能相似）、平行进化（不同区域物种间特征的相似与平行发展，有袋类与真兽类）。,小进化研究物种内性状的维持与变异规律，早期的方法是分析世代间个体的变化，推演其进化历史，但对于有性繁殖物种，需考察整个种群的特征，因为在一个稳定的种群内遗传结构是稳定的，即使个体差异明显也没有新种的诞生。这一新的思想同时也明确了进化研究的主题，如生殖竞争、群迁移、环境适应性等。,进化中的物种大爆发和集群绝灭：,利用进化谱系和化石资料发现阶段性的物种大辐射，如6.5亿年前的原叶植物大量出现，5.3亿年前的寒武纪大爆发，出现了现代所有的动物门类。同样，集群灭绝也是很显著的，其中五次的统计见表。,爆发和灭绝的更替现象：,每次大的绝灭之后会有一个大的辐射进化出现，留出一段空白的空间，如蓝细菌衰落后多细胞生物繁盛，三叶虫、腕足动物消失后鱼类出现，恐龙绝灭后哺乳动物大发生，这是一种生物发生的不连续性和更替发生的相关性，而且具有明显的进化层次的飞跃。,3,。,Reptilian Repast:Ancient mammals preyed on young dinosaurs,Only a few years ago,it was easy to pity the mammals that lived during the Age of Dinosaurs.Most paleontologists presumed that those tiny,shrewlike creatures,thrived only by remaining out of sight.Perhaps relegated to a nocturnal lifestyle,these creatures scurried about furtively and ate insects,worms,and other invertebrates.,Two nearly complete sets of fossilized animal remains from 130-million-year-old rocks in China are revealing fresh details about the size and dietary habits of ancient mammals.The newly described finds counter the common presumption that such creatures remained small and ecologically suppressed until dinosaurs became extinct about 65 million years ago.,The larger of the two finds,a 1-meter-long mammal dubbed,Repenomamus,giganticus,had a stout build and squat posture like that of modern-day badgers.The wear pattern on the creatures teeth hints that the mammal was a young adult when the lethal eruption occurred,says Meng.,The other set of remainsin some ways,the more astounding oneis a nearly complete specimen of,Repenomamus,robustus,a smaller cousin of,R.giganticus,.This opossum-size species was first described from fragmentary remains about 5 years ago.,Within the well-preserved rib cage of the new specimen,the researchers found a compact wad of broken bones and teeth.Some of those remains suggesting that the bones derive from prey that had been dismembered and swallowed in chunks.,Comparisons with known fossils suggest that those fragments belong to a hand-length hatchling of a,Psittacosaurus,a common plant-eating dinosaur that grew to a length of around 2 meters.,The dinosaur-as-prey scenario upsets long-held paleontological contention by suggesting that predatory mammals may have influenced dinosaur evolution.For example,some feathered dinosaur contemporaries of,Repenomamus,over time became smallerand thus presumably better equipped to fly or escape predation.At the same time,some mid-size dinosaurs were becoming larger in perhaps another evolutionary response to mammalian predation.,生物对环境的适应与环境对生物进化的影响：,在进化上适应含有个体生存力和繁殖力提高的两层含义，而且是针对某一特定环境的适应，当时间和空间改变后，原来的适应与不适应都会发生变化，引起物种的进化或淘汰。,地球生命的发展与环境和气候的变迁是紧密联系的，大气成分的变化与温度改变相关，冰川的形成使物种的分布变化和绝灭。但由于热带环境中物种多样性高，地方化程度高，因而损失也最大。当然物种的绝灭还与其他事件有关，如推测外星的撞击引起恐龙灭绝。,对外星生命的探索：由于在地球上没有获得生命起源的直接证据，同时从陨石撞击的现场获得了一些能够支持生命的物质，甚至蛋白质，科幻小说家们极具吸引力的著作也诱惑着人们去探索外星系存在生命的可能，著名的计划是火星探测。,四、人类的起源进化,动物界Animalia、脊索动物门Chordata、脊椎动物亚门Vertebrata,哺乳动物纲Mammalia,真兽亚纲Eutheria,灵长目Primates,类人猿亚目Anthropoidea,人科Homonidea,人属Homo,人种sapienes,目前的观点是：,440-360万年前人科化石-猿；,人属化石能人100200万年前，会制造工具，群居；,直立人100万年前，属于旧石器文化，原始的社会组织；,30万年前智人，,4万年前晚期智人，出现肤色不同的人种。,蒙古人、高加索人、黑人、澳洲人、美洲印第安人，,对于现代人的来源有两种观点：一种认为来源于非洲，一种认为先从非洲扩散出来独立进化。在人类起源研究中对缺乏体毛和性行为不同于其他动物的原因，不清。,人与动物的区别：许多动物具有使用工具的能力和复杂的思维，但只有人是文化的创造者和拥有者，创造文化的三要素：使用工具的双手、发达的大脑、社会性生活。,文化进化：,由于人类使用语言而不同于动物的特征，人兼有生物个体和文明社会成员的双重品格，受着生物法则和社会法则的制约，生物法则注重本能和个人利益的最大化，社会法则关注对个人利益的尊重和对社会整体利益的发扬，两者应该是一种相互依赖的关系。,生物与文化的协同进化：,随着文明程度的提高，人类的生物进化属性越来越受到社会因素的影响，,1）医疗保健的普及使社会成员的生存机会趋于平等，但对某些疾病患者的淘汰在提升，如心脏病、艾滋病；,2）文明病的多发使人类对环境的适应力下降，但对于潜在能力的开发具有促进作用。文化既抑制又促进人类新的进化动力机制，并给生物进化提出新的研究课题，如文明的发展要与地球的生物圈处在良性的发展循环中。,3）智力高低与后代数量没有直接联系，但个体生存对智力要求的压力在上升；,4）一夫一妻制是文明的表现，也有利于提高对后代的抚育，但限制了性选择的生物学优势；,丁克家庭：心理障碍？自由选择？,BPA fosters diabetes-promoting changes,Low doses alter insulin secretion-February 9th,2012,An ingredient in plastics and food-can linings coaxes cells from the pancreas to inappropriately secrete the hormone insulin,a finding that bolsters earlier links between type 2 diabetes and low-dose exposure to the chemical.,胰,pancreas,胰是人体的第二大腺，由外分泌部和内分泌部两部分组成。,外分泌部的腺细胞分泌胰液，经各级导管，流入胰腺管，胰腺管与胆总管共同开口于十二指肠。,内分泌部是指散在于外分泌部之间的细胞团-胰岛，它分泌的激素直接进入血液和淋巴，主要参与糖代谢的调节。,Bisphenol-A,or BPA,can mimic the effects of estrogen,a hormone that is involved in regulating insulin production in the body.Although controversy persists over BPAs potency as an estrogen mimic,the new study,published online February 8 in,PLoS ONE,finds that the pollutant is every bit as potent as the bodys natural estrogen in terms of triggering insulin release.,The new work shows that BPA stimulates insulin release through a hormone-activating protein called estrogen receptor beta,or ER-beta.,Tiny concentrations of either estrogen or BPA boost the release of insulin.When his group tested mice engineered to produce no ER-beta,the effect went away,demonstrating that the protein is integral to BPAs perturbation of insulin secretion.,“I dont think BPA alone will cause type 2 diabetes,”says Franck Mauvais-Jarvis of Northwestern Universitys Feinberg School of Medicine in Chicago.Dozens of environmental chemicals can mimic hormones,he says,“and I suspect its a cocktail of these nasties that predisposes individuals to developing metabolic disease,whether its type 2 diabetes or obesity.”,人类行为的奇特,Investing on a Whiff:Chemical spray shows power as trust booster,Some people smell fear in potential business partners.Others smell a rat.But individuals who smell a certain brain hormone become unusually trusting of others in financial transactions,according to a new report.,Men who inhale a nasal spray spiked with oxytocin,垂体后叶素,give more money to partners in a risky investment game than do men who sniff a spray containing no active ingredient,say economist Ernst Fehr of the University of Zurich and his colleagues.,Previous studies of nonhuman animals had suggested that oxytocin in the brain works as both a hormone and a neurotransmitter,fosters the trust needed for friendship,love,families,economic transactions,and political networks.,Oxytocin specifically affects an individuals willingness to accept social risks arising through interpersonal interactions,he and his colleagues conclude in the June 2,Nature,.,The scientists studied oxytocins influence on male college students playing an investment game.One man in each pair was randomly assigned to play the role of an investor and the other to play the role of a trustee.,Among the investors who had inhaled oxytocin,about half gave all their tokens to trustees,and most of the rest contributed a majority of their tokens.In contrast,only one-fifth of investors who had inhaled a placebo spray forked over all their tokens,and another one-third parted with a majority of their tokens.,The oxytocin influence is a remarkable finding,says neuroscientist Antonio Damasio of the University of Iowa College of Medicine in Iowa City in an editorial published with the new report.,Worries may arise that crowds of people will be sprayed with oxytocin at political rallies or other events to induce trust in speakers,Damasio notes,地球悄现超级新人类,据俄罗斯真理报12月8日报道，据俄罗斯社会,科学,院的科学家们称，地球上现在似乎存在一种新的人种“深蓝孩童”。他们自称有超能力，可以看到灵异现象，能预测到将要发生的事情；他们的共同特征是智力很高、直觉性强，非常敏感等；从人体能量摄影的,图片,中发现，代表精神力的蓝色，在他们身上特别明显，因此被称为“深蓝孩童”,鲍里斯：“深蓝孩童”的典型,在俄罗斯伏尔加格勒地区，1997年诞生一个不同寻常的小男孩。他几乎从来不哭，也从未生过病；八个月大的时候，他就能说出整句话，没有任何语法和发音错误；父母给他的玩具，他也能利用几何学原理正确地组装起来。,当鲍里斯两岁的时候，他开始用蓝色和紫罗兰色涂抹一些东西。还不到三岁，他就可以告诉父母一些关于宇宙的知识。,今年夏天的时候，俄罗斯社会科学院地磁和无线电研究所的科学家们拍到了他身上的光环。弗拉迪斯拉夫卢戈夫金教授说：“他有着深蓝色的能量光谱，这代表他是一个快乐而拥有高智商的人。,但是，也有很多人持不同意见，这种情况可能是因为现代孩子们的基因发生突变，引起孩童们的精神和智力特殊反应。“这可能是我们身体自身散发出的一种波状辐射，也可能是我们地球磁场产生的作用，每个人都可以成为深蓝孩童”。,人类起源的新证据,Evolutions Child:Fossil puts youthful twist on Lucys kind,As fossil hunters crossed a dusty slope of Ethiopias Dikika region on Dec.10,2000,one noticed a childs face bones poking out of the ground.Now,after years of painstaking work to remove the ancient individuals skull and some of the other bones from sandstone,researchers have announced that this discovery represents the oldest and most complete fossil child in our evolutionary family.,YOUNG BUT OLD.The Dikika childs flat nose and projecting face look chimplike,but the Ethiopian fossil comes from a 3.3-million-year-old human ancestor that belongs to the same species as the famous Lucy skeleton.,The shape of the Dikika girls thighs and shins indicate that she walked upright,even at age 3,the researchers hold.However,several apelike lower-body traits support the view that,A.afarensis,sometimes climbed in trees,For instance,as in other,A.afarensis,specimens and chimps,the new specimens finger bones are long and curved.Computerized tomography images of the inner ear show semicircular canals,crucial for maintaining balance,like those of chimps.,This skeleton is really important because its so complete,comments anthropologist Tim D.White of the University of California,Berkeley.But its a black box until its been fully cleaned and properly analyzed.,Lucys feet were made for walking,The bones of a human foot curve upward to form arches,including a toe bone that corresponds in crucial ways to a 3.2-million-year-old Australopithecus afarensis toe fossil.,Researchers say that this shared toe trait indicates that early hominids walked much as people do today.,A tiny 3.2-million-year-old fossil found in East Africa gives Lucys kind an unprecedented toehold on humanlike walking.,the scientists report in the Feb.11,Science,.,Scientists have argued for more than 30 years about whether Lucy and her kin mainly strode across the landscape or split time between walking and tree climbing.,News of arched feet in these hominids comes on the heels of a report that a recently discovered,A.afarensis,skeleton,dubbed Big Man,displays long legs,a relatively narrow chest and an inwardly curving back,signs of a nearly humanlike gait.,我们为何在此？我们从何而来？,霍金今天上午的演讲全文,：,五、生命的适应,特殊点：繁殖力高、门齿发达（无齿根、终生生长）。,草原犬鼠,Prairie dog,复杂而有趣的化学通讯,Bird flu less deadly,but more widespread,than official numbers suggest,The deadly H5N1 avian influenza virus may not be quite so lethal after all,an analysis of more than 12,000 blood samples suggests.,Since 2003,the World Health Organization has recorded 573 cases of humans infected with bird virus.Of those,58.6 percent have died,leading to great concern that the virus could cause a devastating pandemic if it adapts to spread easily among humans.,But many more people may have contracted the virus and fought it off with few or no symptoms,suggest Peter Palese,Taia Wang and Michael Parides of Mount Sinai School of Medicine in New York City.The team analyzed other researchers data on a total of 12,677 people from seven countries where the virus has been seen and who may have been exposed to the virus.,In general,about 1 to 2 percent of the people carried antibodies against the H5N1 virus,indicating that they had been infected at some point.,A higher infection rate than expected isnt good news.The more people infected,he says,the more chances the virus has to adapt itself so that it can be passed from person to person.,the researchers report online February 23 in,Science,.,钱永建与荧光蛋白,钱永健利用绿色荧光蛋白开发出各种荧光染料，广泛应用于生物和医学实验。使用这些荧光材料作出的最具代表性实验莫过于2007年的“脑虹”。,其他两位获奖者是：,下村修和马丁查尔菲,瑞典皇家科学院在公报中专门提到“脑虹”实验，公报说：“在一次引人入胜的实验中，研究人员成功运用如万花筒般的多种颜色标记老鼠大脑中不同神经细胞。”,除了应用于科学研究，绿色荧光蛋白还应用于艺术领域。应美国芝加哥艺术家爱德华多卡奇要求，研究人员于2000年制造出了一只能发出绿色荧光的兔子。,电玩与脑功能,Playing the computer game boosted brains gray matter。,Playing the classic shape-fitting computer game,which celebrates its 25th anniversary this year,for just three months may boost the size and efficiency of parts of the brain。,Brain scans revealed that certain regions of gray matter an information-processing mix of brain cells and capillaries grew thicker in 15 adolescent girls。,Among the regions showing gray matter increases were portions of the frontal and temporal lobes of the brain thought to be important for planning complex movements and integrating information from the senses.,New look suggests brains anatomy determines its function,-June 30th,2008,Earlier research pinpointed an area of the brain called the,default network,a group of br