n,or on<br /> Que h Cute  usearchf Que csearch searchf Que t Cuties esearchh Trimmingsexystrippedmomanddaughter s Trimmingsexystrippedmomanddaughter , Cuties n Index  searchi Que ) Que m Trimmingsexystrippedmomanddaughter c Cuties oasearcha<img src="http://www.iqsdirectory.com/industry/images/bulk_material_handling.jpg"/>i Cute e Index   Cute h Index c<img src="http://img.alibaba.com/img/buyoffer/103622701/REFURBISHED_ANCHOR_HANDLING_VESSELS.jpg"/>  Index ro Cute   Cuties n<br />or on the host,but do not multiply,The main microparasites<br />are viruses,bacteria,fungi and protozoans,Helminth worms<br />and insects are important macroparasites,A large group of<br />insect macroparasites are parasitoids,which lay eggs in or on<br />the body of their insect host,and usually cause the death of<br />the host.<br />Key Notes<br />The diversity of<br />parasites<br />K1 THE NATURE OF PARASITISM<br />¼ÄÖ÷¶Ô¼²²¡µÄ<br />·´Ó¦<br />¼¹×µ¶¯Îﱻ΢¼ÄÉúÎï¸ÐȾºó²úÉúÇ¿ÁÒµÄÃâÒß·´Ó¦¡£Õâ<br />ÖÖ·´Ó¦Ö÷ÒªÓÐÁ½Öֳɷ֣º£¨ i£©Ï¸°ûÃâÒß·´Ó¦£¬Ìض¨Ï¸<br />°ûÖ±½Ó¹¥»÷²¡Ô­Ìåϸ°û£¬ºÍ£¨ ii£© B-ϸ°ûÃâÒß·´Ó¦£¬<br />ʹ¿¹ÌåÁ¿ÉÏÉý¡£³õ´Î±»²¡Ô­Ìå¸ÐȾºó£¬ÃâÒß¼ÇÒä¶Ôδ<br />À´Í¬ÑùµÄÇÖÏ®²úÉú¿ìËÙ·´Ó¦£¬µ¼ÖÂÃâÒß¡£ÎÞ¼¹×µ¶¯Îï<br />ºÍÖ²ÎïÒ²¿ÉÒÔÒÖÖƸÐȾ£¬µ«·½Ê½½Ï¼òµ¥£¬Í¨³£½ÏÉÙÌØ<br />»¯»úÖÆ¡£ÃâÒßÔì³ÉµÄDZÔÚ¼ÄÖ÷¼õÉÙ£¬Ê¹Î¢¼ÄÉúÎïµÄ·±<br />ÈÙ -ºÍ -ÆƲú¶Ô²ß¼ÓÇ¿£¨¼û K2£©<br />´«²¥·½Ê½ ¼ÄÉúÎï¿ÉÒÔºáÏò´«²¥£¨ÔÚÖÖȺ¸öÌåÖ®¼ä£©£¬»òÔÚÉÙÊý<br />Çé¿öÏ£¬×ÝÏò´«²¥£¨´ÓĸÌåµ½ºó´ú£©¡£ºáÏò´«²¥»òÖ±<br />½Ó»ò¼ä½Ó£¬ÓÉ´«²¡Ã½½é£¨ÈçÎÃ×Ó£©»òÖмä¼ÄÖ÷×öÖн顣<br />Parasite transmission can be either horizontal (among members<br />of a population) or,less commonly,vertical (passed from<br />mother to offspring),Horizontal transmission may either be<br />direct or indirect,mediated by a vector (e.g,a mosquito) or an<br />alternate host.<br />Modes of<br />transmission<br />In vertebrates,infection by microparasites results in a strong<br />immunological response,There are two components to this<br />response,(i) the cellular immune response,where specialized<br />cells directly attack pathogen cells,and (ii) the B-cell immune<br />response,which gives rise to antibodies,After the first infection<br />by a pathogen,immunological memory creates a raid response<br />to future attacks by the same organism,resulting in immunity,<br />Invertebrates and plants also may suppress infections,but by<br />less sophisticated,and usually less specific mechanisms,The<br />loss of potential hosts which immunity engenders accentuates<br />the boom-and-bust strategy of microparasites (see Topic K2),<br />Host response<br />to disease<br />¸´ÔÓµÄÉú»îÊ· Ðí¶à¼ÄÉúÎïÔÚÆäÉú»îÊ·Öв»µÃ²»×ª»»¶þ»òÈýÖÖ¼ÄÖ÷¡£<br />¶ÔÕâÖÖ¸´ÔÓµÄÉú»îÊ·ÓÐÈýÖÖ²»Í¬µÄ½âÊÍ£º£¨ i£©½»Ìæ¼Ä<br />ÉúÊDZ»¼ÄÉúÎï¸ÐȾµÄ´«²¡Ã½½é£¨²»ÊÊÓÃÓÚ²»¿ÉÄܳÉΪ<br />´«²¡Ã½½éµÄ²»¶¯¼ÄÖ÷£©£»£¨ ii£©³öÏÖ×îÊÊÉú¾³ÀûÓã¬ÔÚ<br />ÕâÖÖ»·¾³ÖУ¬²»Í¬¼ÄÖ÷ÖÖÊDz»Í¬¼¾½Ú»ò²»Í¬Éú»îÊ·½×<br />¶ÎµÄ×î¼Ñ×ÊÔ´£»£¨ iii£©ÕâÖÖģʽÆðÒòÓÚ½ø»¯Ô¼Êø£¬ÒòΪ<br />¼ÄÉúÎïÔÚÆäÉú»îÊ·µÄij½×¶ÎÖи߶ÈÊÊÓ¦Ò»ÖÖ¼ÄÖ÷£¬Ëù<br />ÒÔËüÃDz»ÄÜÀ뿪¸Ã¼ÄÖ÷£¬¼´Ê¹ÔÚÆäËûµØ·½ÄÜ»ñµÃ¸ü¸ß<br />µÄÀûÒæ¡£<br />Many parasites obligately switch between two or three host<br />species in the course of their life cycle,Three different<br />explanations have been advanced to explain such complex<br />life cycles,(i) alternate hosts are vectors which have been<br />attacked by the parasite (this cannot apply to immobile<br />hosts which cannot be vectors); (ii)optimal habitat use is<br />occurring,where different species are the optimal resource<br />in different seasons,or for different life cycle stage; (iii) the<br />pattern is due to evolutionary constraint,as parasites<br />become highly adapted to one host for part of their life<br />cycle,they are unable to leave it even though the rewards<br />are higher elsewhere,<br />Complex life<br />cycles<br />Ïà¹ØÖ÷Ìâ ³öÉúÂÊ¡¢ËÀÍöÂʺÍÖÖȺÔö³¤£¨ H2£© ¼ÄÉúµÄ¶¯Ì¬£¨ K2£©<br />²¶Ê³µÄÐÔÖÊ£¨ J1£©<br />Éç»áÐÔ¼ÄÉúÎï ¨DÉç»áÐÔ¼ÄÉúÎÓëÆä¼ÄÖ÷Ö®¼äÓÐÒ»ÖÖÍêÈ«²»Í¬µÄ¹Øϵ¡£<br />Éç»áÐÔ¼ÄÉúÎﲻͨ¹ýÉãʳ¼ÄÖ÷×éÖ¯»ñÒ棬¶øÊÇͨ¹ýÇ¿<br />ÆȼÄÖ÷ÌṩʳÎï»òÆäËûÀûÒæ¶ø»ñÀû¡£ÕâÖÖ¹Øϵ·¢ÏÖÔÚ<br />¶Å¾é£¬ËüÃǽ«µ°ÏÂÔÚ±ðÖÖÄñµÄ³²ÖУ¬ÈÃÕâÖÖÄñËÇÓýÆä<br />Ó×Äñ¡£ÕâÖÖ¹Øϵ»¹·¢ÏÖÔÚһЩÂìÒÏÖÖÀ࣬ËüÃÇÆÈʹÆä<br />ËûÖÖ¹¤ÒϸøËüÃǵÄÓ×ÌåʳƷ»òÆäËûÀûÒæ¡£<br />Related topics Natality,mortality and population The dynamics of parasitism (K2)<br />growth (H2) The mature of predation (J1)<br />A completely different form of relationship is found<br />between¡® social parasites¡® and their hosts,Social parasites<br />gain benefit from their animal hosts not by feeding on their<br />tissues but by coercing them to provide food or other<br />benefits,Such relationships are found in cuckoos which lay<br />their eggs in the nests of other bird species,which then<br />undertake the rearing of the young,and in some ant species<br />which coerce the workers of another species to provision<br />their brood.<br />Social parasites<br />K2 ¼ÄÉúµÄ¶¯Ì¬<br />Òª µã<br />¼ÄÉúÎï -<br />¼ÄÖ÷¶¯Ì¬<br />¼¹×µ¶¯Îï¼ÄÖ÷Ò»°ã¶Ô¼ÄÉú²úÉúÃâÒß¡£ÕâЩÃâÒß¼ÄÖ÷²»<br />ÄÜÔÙ±»¼ÄÉúÎïÀûÓã¬Òò¶øÒ׸ÐÖÖȺµÄ´óС¼õÉÙ¡£Õâʹ<br />¼²²¡µÄ´«È¾Á¦½µµÍ¡£È»¶ø£¬Ëæ×ÅеÄÒ׸мÄÖ÷¼ÓÈëÖÖ<br />Ⱥ£¨ÈçиöÌå³öÉú£©£¬¼²²¡µÄ´«È¾Á¦»áÔÙ´ÎÔö¼Ó¡£Òò<br />´Ë£¬´«È¾²¡ÓÐÑ­»·µÄÇ÷ÊÆ£¬ÔÚеÄÒ׸иöÌåÔö¼ÓʱÉÏ<br />Éý£¬ÔÚÃâÒßˮƽÉÏÉýʱϽµ¡£µ±Ò»ÖÖÖ²¡¼ÄÉúÎï·±Ö³<br />ÂÊϽµÊ±£¬´«È¾Á¦¶ÔÒ׸иöÌå¼ÓÈëµÄ·´Ó¦½ÏÂý£¬¶¯Ì¬<br />´ÓÁ½·åÖ®¼ä¶Ì¼ä¸ôµÄÃ÷ÏÔµÄͬ²½Ñ­»·±äΪͬ²½ÐÔ¼õÈõ£¬<br />¼ä¸ô¼Ó³¤£¬Ö±µ½×îºó¹Û²ì²»µ½Ñ­»·¡£<br />Vertebrate hosts commonly acquire immunity to parasites,<br />These immune hosts are no longer available to the parasites,<br />and the size of the susceptible population is reduced,This<br />results in a fall in the incidence of disease,However,as new<br />susceptible hosts enter the population (for example,by birth),<br />the disease will increase in incidence again,Thus,there is a<br />tendency of diseases to cycle,rising as the number of new<br />susceptibles increases and falling as the level of immunity rises,<br />As the influx of new susceptibles increases and falling as the<br />level of immunity rises,As the reproductive rate of a disease<br />falls,the response of disease incidence to the influx of<br />suscetibles is slower and the dynamics change from clear,<br />synchronous cycles with a short period between peaks to<br />reduced synchrony and longer periodicity until finally no cycles<br />are observable.<br />Key Notes<br />Parasite-host<br />dynamics<br />K2 THE DYNAMICS OF PARASITISM<br />¼ÄÖ÷ ¡ª¡ª<br />¼ÄÉúÎï½ø»¯<br />¼ÄÉúÎïÓëÆä¼ÄÖ÷¼ä½ôÃܵĹØÁª¾­³£µ¼Ö¶þÕßÔÚ½ø»¯ÉÏ<br />µÄÏ໥×÷Ó㬻òЭͬ½ø»¯¡£Ð­Í¬½ø»¯Ê¹¼ÄÖ÷µÄ·ÀÓù»ú<br />ÖÆÌá¸ß£¬¶ø¸ø¼ÄÉúÎï¿Ë·þÕâЩ·ÀÓùµÄͨ· ¡ª¡ªÕâ½Ð×ö<br />¡°¾ü±¸¾ºÈü¡±¡£µ«ÊÇ£¬¼ÄÖ÷Óë¼ÄÉúÎïÖ®¼äµÄЭͬ½ø»¯<br />²¢²»¶¼ÊÇÌá¸ßÐԵġ£ÀýÈ磬Эͬ½ø»¯»á½µµÍ¼ÄÉúÎïµÄ<br />¶¾ÐÔ¡£<br />The close association between parasites and their hosts often<br />results in evolutionary interactions,or coevolution,<br />Coevolution may give rise to defence mechanisms in the host<br />and routes to overcome these defences in the parasite ¨C so<br />called ?arms races¡®,Not all coevolution between host and<br />parasite is escalatory,however,For example,coevolution may<br />lead to the reduction in the virulence of a parasite.<br />Host- parasite<br />evolution<br />΢¼ÄÉúÎﴫȾ<br />²¡Ä£ÐÍ<br />΢¼ÄÉúÎïµÄ·±Ö³ÂÊ£¨ Rp£©¿É±íʾΪÓÉÒ»¸ö¸ÐȾ¼ÄÖ÷Ëù<br />´«È¾µÄиöÌåÊý,Rp =¦ÂSd¡£Èç¹û RpСÓÚ 1£¬Ôò²¡Ö¢´«<br />ȾÁ¦ÔÚ¼ÄÖ÷ÖÖȺÖÐϽµ£¬¶øÈç¹û Rp´óÓÚ 1£¬¼²²¡´«È¾ÉÏ<br />Éý¡£¸ÃÄ£ÐÍ¿ÉÔ¤²â£¨ i£©¼ÄÖ÷ËÀÍö¿ìËÙ·¢Éúʱ½µµÍ¶¾ÐÔ<br />µÄ½ø»¯£¬£¨ ii£©×ª»»¼ÄÖ÷ʹ¼ÄÉúµÄÊʺ϶È×î´ó£¬£¨ iii£©<br />¶Ô ijһ¼ÄÉúÎïÀ´ËµÓÐÒ»¼ÄÖ÷ÃܶÈãÐÖµ£¬µÍÓÚ¸ÃãÐÖµ¼Ä<br />ÉúÎï²»ÄÜ´æ»î£¬ºÍ£¨ iv£©Ò×´«È¾Ê±¼ä¶ÌµÄ¼²²¡²»ÄÜÔÚС<br />ÖÖȺÖгÖÐø¡£<br />The reproductive rate of a microparasite (Rp ) can be<br />expressed as the number of mew cases that will arise from<br />an infected host, Rp =¦ÂSd,If Rp is less than one,then the<br />disease incidence is falling in the host population,whilst if<br />Rp is greater than one,the level of disease is increasing,<br />This model can predict (i) the evolution of reduced<br />virulence when host deaths occur rapidly,(ii) altered host<br />behavior to maximize parasite fitness,(iii) that there is a<br />threshold density of hosts for a given parasite,below<br />which the parasite will not survive,and (iv) that diseases<br />with short periods of infectivity should not persist in small<br />populations.<br />A model of<br />microparasite<br />disease<br />¼ÄÉúÎïÖÖȺµÄ<br />ÒìÖÊÐÔ<br />һЩ¼²²¡ÊÇÎȶ¨µÄ£¬¶øÁíһЩ½ø»¯ÁËͨ¹ý±äÒì¡°ÌÓÀ롱<br />¼ÄÖ÷·ÀÓùµÄÊֶΡ£ÈËÀà¡°º¢Í¯Ê±ÆÚ¡±µÄ¼²²¡ ¡ª¡ªÂéÕî¡¢<br />ÈùÏÙÑס¢Ë®¶»µÈ´ó²¿·Ö¾ÖÏÞÓÚº¢×Ó£¬ÒòΪËüÃǵĿ¹Ô­<br />Îȶ¨¡£Óë´ËÏà¶Ô£¬¼ÄÉúÎïÈçÁ÷¸Ð²¡¶¾¡¢±Ç²¡¶¾£¨ÆÕͨ<br />¸Ððԭ£©ºÍɳÃÅÊϾú£¨ Salmonella£©¾ßÓпɾ­³£¼ÓÈëµÄ<br />ºÜ¶à±äÒìÐÍ¡£¼ÄÖ÷Òò´ËÒª¾­³£Óë±ä»¯µÄ¼ÄÉúÎï¾ü¶ÓµÄ<br />½ø¹¥¶ø½øÐÐÕ½¶·¡£<br />Whilst some diseases are stable,others have evolved<br />?escapes¡® from host defences by variation,The<br />?childhood¡® diseases of humans ¨C measles,mumps<br />chickenpox etc,are largely restricted to children<br />because they are antigenically stable,In contrast,<br />parasites such as influenza,rhinoviruses (the cause of<br />the common cold) and Salmonella have multitudes of<br />strains which are constantly being added to,Hosts<br />therefore have a constantly varying army of attacking<br />parasites to contend with.<br />Heterogeneity in<br />host populations<br />¼ÄÉú×÷ΪÓÐÐÔ<br />·±Ö³µÄÔ­Òò£º<br />,ºì»Êºó,<br />ÓÐÐÔ·±Ö³µÄ´ú¼Û¸ßÓÚÎÞÐÔ·±Ö³£¬ÒòΪÐÛÐÔ²»²úºó´ú£¬<br />ËùÒÔÖÖȺÔö³¤Âý¡£Òò´Ë£¬Ò»¶¨´æÔÚһЩ¿ÉƽºâÀûÒæ¡£<br />¾ÝÈÏΪÓÐÐÔ·±Ö³µÄÖ÷ÒªÀûÒæÊDzúÉúÒÅ´«±äÒ죬À´¶Ô¸¶<br />¼ÄÉúÎïÆÕ±é´æÔڵĺͱ仯×ŵĹ¥»÷¡£<br />Ïà¹ØÖ÷Ìâ ³öÉúÂÊ¡¢ËÀÍöÂʺÍÖÖȺÔö³¤£¨ H2£© ¼ÄÉúµÄÐÔÖÊ£¨ K1£©<br />²¶Ê³µÄÐÔÖÊ£¨ J1£© Éú̬ѧÖеÄÐÔ£¨ N2£©<br />¼ÄÖ÷ÖÖȺµÄÒì<br />ÖÊÐÔ<br />¼ÄÖ÷ÖÖȺÄÚ¸öÌåÔÚ±»¼ÄÉúÎï¸ÐȾµÄ·çÏÕÉϺÜÉÙÊǾùµÈ<br />µÄ¡£¸öÌåµÄÄêÁä¡¢ÐÐΪ¡¢½¡¿µ×´¿ö¡¢Óë±»¸ÐȾ¸öÌåµÄ<br />½Ó½ü³Ì¶ÈÒÔ¼°ÌرðÖØÒªµÄ¸öÌåµÄÒÅ´«ÐÔÒ×»¼²¡³Ì¶È£¬<br />¶¼»áÓ°Ïì½á¹û¡£<br />Related topics Natality,mortality and population The mature of parasitism (K1)<br />growth (H2) Sex in ecology (N2)<br />The mature of predation (J1)<br />Individuals within a host population are very rarely equally<br />at risk of being successfully attacked by a given parasite,<br />The age,behavior,state of health,proximity of the infected<br />individuals,and,of particular importance,the genetic<br />predisposition of an individual will all influence the<br />outcome.<br />Heterogeneity in<br />host populations<br />The costs of sexual reproduction are high compared to<br />asexual reproduction,as males produce no offspring,so<br />population growth is slow,Therefore,there must be some<br />balancing benefit,It has been suggested that the main<br />benefit of sex is to produce genetic variation to overcome<br />the ubiquitous and dynamic attack of parasites.<br />Parasites as a<br />reason for sex ¨C<br />the<br />¡®Red Queen¡¯<br />L1 »¥Àû¹²Éú<br />Òª µã<br />»¥Àû¹²ÉúºÍ<br />¹²ÉúÏÖÏó<br />»¥Àû¹²ÉúÊDz»Í¬ÖÖÁ½¸öÌå¼äÒ»ÖÖÕýµÄ»¥»Ý¹Øϵ£¬¿ÉÔö<br />¼ÓË«·½µÄÊʺ϶ȡ£»¥Àû¹²Éú¿ÉÒÔÊǹ²ÉúÐԵģ¬ÉúÎïÌå<br />ÒÔÒ»ÖÖ½ôÃܵÄÎïÀí¹ØϵÉú»îÔÚÒ»Æð¡£<br />רÐÔ»¥Àû¹²Éú ÓÐЩ»¥Àû¹²ÉúÕߣ¬ÈçµØÒ£¬ÊÇÓÀ¾ÃÐԳɶÔ×éºÏ£¬ÆäÖÐ<br />Ò»·½»òË«·½²»ÄܶÀÁ¢Éú»î¡£´ó¶àÊý¹²ÉúÕßÊÇרÐÔ¹²Éú£¬<br />»¹ÓÐһЩ·Ç¹²ÉúÐԵĻ¥Àû¹²ÉúÒ²ÊÇרÐԵģ¬ÈçÄ¢¹½ -¸û<br />×÷ÒÏÖ®¼äµÄ»¥Àû¹²Éú¡£<br />Mutualism is a positive reciprocal relationship between<br />two individuals of different species which results in<br />increased fitness for both parties,Mutualism may be<br />symbiotic,in which the organisms live together in close<br />physical association.<br />Key Notes<br />Mutualism and<br />symbiosis<br />L1 MUTUALISM<br />Some mutualisms,such as lichens,are permanent<br />pairings in which one or both partners cannot lead an<br />independent life,Most symbioses are obligate,as are<br />some nonsymbiotic mutualisms,such as those formed by<br />fungus-farming ants.<br />Obligate<br />mutualism<br />¼æÐÔ»¥Àû¹²Éú »¥Àû¹²ÉúµÄ¶àÊýÊÇ·ÇרÐԺͻú»áÐԵġ£ÕâЩ»¥Àû¹²Éú<br />¿ÉÄÜÊÇÉ¢¿ªµÄ£¬°üº¬Óв»Í¬µÄÎïÖÖ»ìºÏ£¬ÈçÐí¶à´«·Û<br />ÕßÓëÆä´«·ÛÖ²ÎïÖ®¼äµÄ»¥Àû¹²Éú¡£<br />´« ·Û<br />ÒìÐÍÔÓ½»Ö²ÎïÐèÒª½«Æ仨·ÛתÒƵ½Í¬ÖÖÖ²ÎïµÄÖùÍ·ÉÏ£¬<br />²¢½ÓÊÜͬÖÖÖ²ÎïµÄ»¨·Û¡£Ò»Ð©Ö²ÎïÖÖÀà¿¿·çÀ´´«²¥»¨<br />·Û£¬Èç¹ûÖ²ÎïÉú³¤ÔÚ¹ã´óµÄÖ²ÎïÖÖÀ൥һµÄµØ·½Èç²Ý<br />µØºÍËÉÁÖ£¬ÕâÖÖ´«²¥·½Ê½»áºÜÓÐЧ¡£µ«ÊÇ´ó¶àÊý¿ª»¨<br />µÄË«×ÓÒ¶Ö²ÎÒÀ¿¿À¥³æ¡¢Äñ¡¢òùòð»òСÐͲ¸È鶯Îï<br />À´´«²¥»¨·Û£¬×÷Ϊ½»»»£¬ÕâЩ¶¯Îï»òÒÔ»¨ÃÛ»òÒÔ»¨·Û<br />±¾ÉíΪʳ¡£<br />The majority of mutualisms are nonobligatory and<br />opportunistic,They may be diffuse,involving a varying<br />mixture of species,as occurs between many pollinators<br />and their plants.<br />Facultative<br />mutualism<br />An out crossing plant needs to transfer its pollen to the<br />stigma of a conspecific plant,and receive pollen from a<br />conspecific,Some plant species rely on the wind to<br />achieve this,which can work acceptably well if plants<br />grow in large homogeneous stands of few species,as<br />occurs in grasslands and pine forests,However,in most<br />species of flowering dicotyledonous plants,insects,birds<br />bats or small mammals are employed to transfer pollen<br />from plant to plant,usually in exchange for either nectar or<br />pollen itself as a foodsource.<br />Pollination<br />ÖÖ×ÓÀ©É¢ ´óÐÍÖÖ×ÓÎÞ·¨ÓÐЧµÄ±»·ç´«²¼£¬³ý·Ç¿¿Ë®´«²¼£¨ÈçÒ¬<br />Ê÷µÄÖÖ×Ó£©£¬»òÒÀ¿¿¶¯ÎïÀ´É¢²¼¡£Äö³Ý¶¯Îï¡¢òùòð¡¢<br />ÄñºÍÂìÒ϶¼ÊÇÖØÒªµÄÖÖ×ÓÀ©É¢Õß¡£<br />·ÀÓùÐÔ»¥Àû<br />¹²Éú<br />һЩ»¥Àû¹²ÉúΪÆäÖÐÒ»·½Ìṩ¶Ô²¶Ê³Õß»òÕß¾ºÕùÕßµÄ<br />·ÀÓù¡£ÕâÖÖ·ÀÓùÐÔ»¥Àû¹²ÉúµÄÀý×Ó¼ûÓÚһЩ²ÝºÍ²úÉú<br />Ö²Îï¼îµÄÕæ¾úÖ®¼ä£¬ÒÔ¼°Ðí¶àÖÖÖ²ÎïºÍÂìÒÏÖ®¼ä¡£<br />Large seeds cannot be effectively wind-dispersed,and<br />unless dispersal by water (as occurs in the coconut palm)<br />occurs,such plants are dependent on animals for<br />dispersal,Rodents,bats,birds and ants are all important<br />seed dispersers.<br />Seed dispersal<br />A number of animal species rely to some extent on<br />mutualisms with mutualists which reside within their<br />bodies,Ruminants (deer and cattle) possess a multi-<br />chambered stomach in which bacterial and protozoan<br />fermentation take place,In some termites,which feed on<br />wood,the necessary breakdown enzymes are provided by<br />bacterial mutualists,Intracellular bacterial symbionts<br />which transform amino acids occur in a number of insect<br />groups,including aphids and cockroaches.<br />Symbiotic<br />mutualists within<br />animal tissues and<br />cells<br />¶¯Îï×éÖ¯»òϸ<br />°ûÄڵĹ²ÉúÐÔ<br />»¥Àû¹²Éú<br />һЩ¶¯ÎïÖÖÀàÔÚijÖ̶ֳÈÉÏÒÀÀµÓÚͬÉú»îÔÚÆäÌåÄÚµÄ<br />¹²ÉúÌå¼äµÄ»¥Àû¹²Éú¡£·´Û»¶¯Î¹ºÍÅ££©ÓµÓжàÊÒ<br />裬ÔÚÆäÖз¢Éúϸ¾úºÍÔ­Éú¶¯ÎïµÄ·¢½Í×÷Óá£ÔÚһЩ<br />ÒÔľΪʳµÄ°×ÒÏÖУ¬±ØÐèµÄ·Ö½âøÓÉϸ¾ú¹²ÉúÌåÌṩ¡£<br />ÔÚһЩÀ¥³æÖÖÀ࣬°üÀ¨ÑÁ³æºÍó¯ò룬´æÔÚת»»°±»ùËá<br />µÄϸ°ûÄÚϸ¾ú¹²ÉúÌå¡£<br />Some mutualisms provide one partner with a<br />defense against predators or competitors,Examples<br />of such defensive mutualisms are found between<br />some grasses and alkaloid-producing fungi,and<br />between many plant species and ants.<br />Defensive<br />mutualisms<br />»¥Àû¹²ÉúºÍ<br />½ø»¯<br />»¥Àû¹²Éú¿ÉÄÜÆðÔ´ÓÚ¼ÄÉúÎï -¼ÄÖ÷ºÍ²¶Ê³Õß -ÁÔÎïÖ®¼äµÄ<br />¹Øϵ£¬»òÆðÔ´ÓÚûÓÐЭ×÷»òÏ໥ÀûÒæµÄ½ôÃܹ²ÆÜÎïÖÖ<br />Ö®¼ä¡£È»ºóË«·½µÄ½ø»¯±ä»¯£¨Ð­Í¬½ø»¯£©µ¼ÖÂË«·½´Ó<br />ÕâÖÖ¹ØϵÖлñÒ棬ËäȻҲ¿ÉÄܹ²Éú¡°¶ñ»¯¡±£¬³ÉΪʹ<br />Ò»·½ÊÜÒæ¡¢ÁíÒ»·½ÊÜ·ÇƽºâµÄ°þÏ÷µÄ¼ÄÉú¹Øϵ¡£»¥Àû<br />¹²ÉúµÄÏ໥×÷ÓÃÔÚ¶àϸ°û¶¯Îï½ø»¯¹ý³ÌµÄһЩ¹Ø¼ü½×<br />¶ÎÖÐÆð×ÅÖÐÐÄ×÷Ó᣸ߵÈÉúÎïµÄÐí¶àϸ°ûÆ÷¹Ù£¬°üÀ¨<br />ÏßÁ£ÌåºÍÒ¶ÂÌÌ壬±»ÈÏΪÀ´×Ô¹²ÉúÐÔϸ°û¡£<br />Ïà¹ØÖ÷Ìâ ¾ºÕùµÄÐÔÖÊ£¨ I1£© ¼ÄÉúµÄÐÔÖÊ£¨ J1£©<br />Related topics The nature of competition (I1) The mature of parasitism (K1)<br />Mutualism and<br />evolution<br />Mutualism may have arisen form parasite-host and<br />relationships,or between closely coexisting species<br />with no cooperation or mutual benefit,Evolutionary<br />changes in both partners (coevolution) have then<br />resulted in both partners benefiting from the<br />relationship,although it is possible for mutualisms to<br />?deteriorate¡® into unbalanced exploitation of one<br />partner to the benefit of the other ¨C parasitism,<br />Mutualistic interactions have been central to number<br />of important steps in the evolution of multicellular<br />organisms,Many of the cell organelles of higher<br />organisms,including mitochondria and chloroplasts<br />are believed to be derived from symbiotic bacteria.<br />M1 Éú»îÊ·<br />Òª µã<br />Éú»îÊ·±äÒì ÉúÎïµÄÉú»îÊ·ÊÇÖ¸Æ