生物學導(dǎo)論biology13

1、 Adaptive radiation 適應(yīng)輻射 Behavioral isolation 行為隔離 Biochemical isolation 生化隔離 Convergent evolution 趨同進化 Divergent evolution 趨異進化 Ecological isolation 生態(tài)隔離 Gene flow 基因流 Gradualism 漸進說 Multiregional hypothesis 多地區(qū)進化假說 Out-of-Africa hypothesis 出自非洲假說 Mechanical isolation 機械隔離 Polyploidy 多倍體 Punctuated

2、 equilibrium 點斷平衡模式 Speciation 物種形成13.1 Species: A working definition13.2 How new species originate13.3 Maintaining genetic isolation13.4 The development of evolutionary thought13.5 Evolutionary patterns above the species level13.6 Rates of evolution13.7 the tentative nature of the evolutionary hist

3、ory of organisms13.8 Human evolution Species物種: a population of organisms whose members have the potential to interbreed naturally to produce fertile offspring but do not interbreed with other groups Key ideas: 1) A species is a population of organisms 2) The definition involves the ability of indiv

4、iduals within the group to produce fertile offspring Gene flow 基因流 is the movement of genes within a population because of migration or the movement of genes from one generation to the next by gene replication and reproductionA horseA donkeyA Mule Genetic similarity Those have a great deal of simila

5、rly are assumed to have resulted from populations that have exchanged genes through sexual reproduction in the recent past Two methods thought to be involved in generating new species: geographic isolation and polyploidy Geographic isolation means a portion of a species can become totally isolated f

6、rom the rest of the gene pool by some geographic changeDifferent species or same species? Geographic barriers 地理屏障: geographic features that keep the different portions of the species from exchanging genes, for example mountains, rivers, etc. Subspecies 亞種: genetic differences that accumulate may re

7、sult in regional populations, called subspecies Speciation 物種形成: process of generating new species, occurring only if gene flow between isolated populations does not occur even after barriers are removed Geographic isolation Action of selective agents that choose specific genetic combinations as bei

8、ng valuable Genetic differences becoming so great that reproduction between two groups is impossible Any process that could result in the reproductive isolation of a portion of a species could lead to the possibility of speciation. ExamplesDifference in reproductive timeVariations in genetically det

9、ermined behaviorsGenetically determined incompatibility of pollen Polyploidy generates instant speciation Polyploidy is a condition of having multiple sets of chromosomes rather than the normal haploid or diploid number Corn, potatoes, sugarcane, wheat, garden flowersA polyploid variety of this hibi

10、scus flower, differences in flower size and petal shape.Normal, diploidpolyploid The speciation process typically involves the development of reproductive isolating mechanisms or genetic isolating mechanisms. Habitat preference or ecological isolation Seasonal isolation Behavioral isolation Mechanic

11、al or morphological isolation：insects (lock and key)CroakingVisual displayA male prairie chicken 草原雞 attracts female prairie chickens In each generation, more giraffes would be born than the food supply could support In each generation, some giraffes would inherit longer necks and some would inherit

12、 shorter necks All giraffes would compete for the same food sources Giraffes with longer necks would obtain more food, have a higher survival rate, and produce more offspring As a result, succeeding generations would show an increase in the neck length of the giraffe speciesThe basic evolutionary pa

13、tterns are: Divergent evolution 趨異進化: individual speciation events cause successive branches in the evolution of a group of organisms Extinction 滅絕 Adaptive radiation 適應(yīng)輻射 Convergent evolution 趨同進化 occurs when organisms of widely different backgrounds develop similar characteristics上新馬次馬安琪馬草原古馬始行馬漸新

14、馬 有些生物雖然同出一源，但在進化過程中在不同的環(huán)境條件的作用下變得很不相同，這種現(xiàn)象稱為趨異進化（divergent evolution）。北極熊（Ursus maritimus）是從棕熊（Ursus arctos）發(fā)展而來。 A rapid increase in the number of kinds of closely related species is known as adaptive radiation 趨異進化的結(jié)果使一個物種適應(yīng)多種不同的環(huán)境而分化成多個在形態(tài)、生理和行為上各不相同的種，形成一個同源的輻射狀的進化系統(tǒng)，即是適應(yīng)輻射（adaptive radiation）。

15、 Two situations favor adaptive radiationTwo situations favor adaptive radiation 適應(yīng)輻射 An organism invades a previously unexploited environment. A type of organism evolves a new set of characteristics that enable it to displace organisms that previously filled roles in the environment.Specializations

16、of beaks for different kinds of foodWings as a method of movement and capture insects for foodBut they have completely different evolutionary origins 不同的生物，甚至在進化上相距甚遠的生物，如果生活在條件相同的環(huán)境中，在同樣選擇壓的作用下，有可能產(chǎn)生功能相同或十分相似的形態(tài)結(jié)構(gòu)，以適應(yīng)相同的條件。此種現(xiàn)象稱為趨同進化（convergent evolution）。鯨、海豚等和魚類的親緣關(guān)系很遠，前者是哺乳類，后者是魚類，但體形表現(xiàn)出明顯的相似。 G

17、radualism 漸進說 : gradual changes in the features of specific species in geology and natural history Punctuated equilibrium點斷平衡模式: evolution occurs in spurts of rapid change followed by long periods with little evolutionary changeDarwin, 1858Eldredge & Jay, 1972The concept of evolution can take us

18、 in several different directions Genetic changes do occur Species can change Different populations of the same species show genetic differences New species come into existence智人南方古猿非洲南猿直立人地棲猿阿法南猿尼安特人 Out-of-Africa hypothesis states that modern humans (Homo sapiens) originated in Africa as had severa