Chapter 18 Chapter 9 Charles Darwin-2

Until March 1837, when the famous ornithologist John Gould was studying the bird specimens collected by Darwin, he told him the respective structural characteristics of the little mockingbirds collected from the three small islands of the Grapagos Islands It was only later that Darwin recognized the process of geographic speciation.It was evident that it was some time later that Darwin learned that the finches he collected in the archipelago were also limited to certain small islands.Therefore, Darwin was "When I compared the birds collected from the separate islands of the Grapagos with each other, and with the Uga of the American continent, I was surprised to find that the species and varieties How vague and arbitrary the distinction is."Darwin also came to understand that many populations (as we now call them) are only intermediaries between species and varieties; Claimed immutability and clear boundaries.Darwin's concept of species was thus shaken to its foundations.

The spring of 1837 was the busiest time of Darwin's life, and it was not until the summer of that year that he was able to continue his transformation in the direction of evolution.He wrote in his diary: "(1837) July began to write the first Guangan 'Evolution of Species' (Transmutation of species) notes.The characteristics of the fossils of South America and of the species of the Grapagos Islands have been deeply affecting me since March of this year.These facts (especially the latter) struck all my thoughts. " The encounter with Gould in March 1837 became a turning point in Darwin's thinking.The bankruptcy of the concept of a fixed species caused a domino effect.Suddenly everything takes on a new luster.What he observed on the voyage of the Beagle, which once perplexed him, now seems to have an explanation: "I was struck by a series of events during the voyage of the Beagle: Large fossil animals with armor were found in the rock formations, like the armor of the extant euadillo; second, the way in which closely related animals replaced each other gradually from the South American continent to the south; third, on the Grapagos Islands. The South American characteristics of most fauna, especially the slight differences among the same species on each island; and the fact that none of the islands are very old in a geological sense. It is evident that these facts, and many others, can be explained by the putative species are gradually changing explanations; I have always been haunted by this question.”

("Autobiography": 118-119). The questions of evolution that Darwin was clearly most concerned with were those of species and, more broadly, of the origins of diversity: fossil versus extant fauna, tropical versus temperate fauna, island versus continental fauna. Darwin's method of studying evolution is completely different from Lamarck's. The evolution of diversity has always been in Darwin's mind. It would also be wrong to say that Darwin had since had a clear idea or vision of speciation. Both Kottler (1978) and Sulloway (1979) have pointed out that Darwin vacillated considerably throughout his life on the problem of speciation.In particular, there are indications that he might also have thought that speciation on islands was different from that on the mainland.Even like some modern biologists, Darwin seems to have difficulty understanding the continental barriers that would allow the isolation of primordial species, and believed that his "Principle of character divergence" could overcome this difficulty.

Two extreme interpretations of the development of Darwin's theory of evolution can be found in the literature, which are clearly erroneous.One is to say that Darwin developed all of his theories since once he turned evolutionary.Another extreme explanation is that Darwin changed his mind constantly and in his later years abandoned his previous views completely.Through research in recent years and from Darwin's notes and manuscripts, it was found that at first (1837 and 1838) Darwin did adopt successively and then quickly discarded a series of theories, but after that he more or less persisted in his nineteenth century. The general outlines of the theory advanced in the 1940s, although he sometimes changed his views on the relative importance of certain factors (such as geographical isolation and soft inheritance), he did not go back and make the exact opposite decision.Notwithstanding the foregoing contrary opinion, in fact his account of evolution in the sixth edition (1872) and Descent of Man (1871) and his essays in 1844 and the first edition (1859) Very similar, not much difference.

Darwin and Wallace first took a very different approach to the question of the origin of species than either of their predecessors.Instead of comparing taxa on a time scale (dimension), they compare extant taxa on a geographic scale, that is, groups and species that replace each other geographically.In fact the concept of geographic species was not a completely new idea when Darwin approached the problem in 1837.Buffon may have first noticed the fact that, when one enters from one country to another at a great distance, one finds that many of the species of the first country have quite similar species in the second.For example, when comparing the mammals of Europe and North America, the practical question arises as to whether the beavers, bison, red deer, lynx, and hares in these two continents belong to the same species or to different species. a species.The same question can be asked about birds, insects, and many plants.

After Buffon, the famous zoologist Peter Simon Pallas (1741-1811) also found similar corresponding substitution types when comparing the fauna of Europe and Siberia.Further research shows that the more distant types are often connected by a series of hierarchical intermediary types.The principle of geographical variation was discovered by studies of this type, and it greatly contributed to the eradication of the essentialist conception of species.However, it was not until 1825 that Leopold von Buch drew the following logical conclusion from these observations: A group of individuals of a genus that travels across continents to distant regions, forming varieties (due to differences in geography, food, and soil) that cannot interbreed with other varieties due to segregation (geographical isolation), and thus recover to the original main type.Eventually these varieties became fixed and formed separate species.They may later come again to the range of other varieties modified in the same way, when the two can no longer interbreed, and henceforth behave as "two very different species" (Buch, 1825: 132-133) .

Von Buch insightfully highlights the key to geographic speciation: the spatial isolation of populations, when isolated populations gradually change and simultaneously acquire species-specific traits (most importantly isolation mechanisms) that allow these new species to return Will not mix (hybrid) with parent species when they are in their range.From the very beginning this was very similar to Darwin's theory of speciation, as can be seen from Darwin's notebooks and his early papers.Indeed, throughout Darwin's lifetime he believed that geographical isolation was an important part of speciation.This is confirmed by some passages in it:

"By preventing immigration and consequent competition (not to mention embarrassment), isolation will give time for the gradual improvement of any new variety; at some point this may be important in the formation of new species" (, 105 pages). Referring to species on islands, Darwin remarked: "A large part is endemic, that is to say, formed here and not elsewhere. Islands, therefore, seem at first sight to be useful for the formation of new species." An ideal place." Of course, new species thus formed on islands must have been descended from immigrating animals: "It is almost a general rule that species formed on islands are related to those on the nearest continent or on other neighboring islands" . (399 pages).Referring to the archipelago, Darwin said: "What is really surprising in the case of the Grapagos Islands, and to a lesser extent in similar cases, is the formation of new species on separate islands. did not spread quickly to other islands" (p. 401).

The origin of species—that is, the multiplication of species—was such a central issue in Darwin's theory of evolution that one would have thought it would have been devoted to its own chapter out of fourteen.However, this is not the case. The discussion of speciation occupies only a part of Chapter 4 ("Natural Selection", pp. 88-130), and this chapter is mainly concerned with the causes of evolutionary change and divergence.On reading this chapter one gets the impression that the analysis is insufficient.Although Darwin didn't use many words to address the issue in this chapter, he actually thought of geographic isolation and natural selection as alternative mechanisms of speciation.Strangely, this apparent confusion has not been properly analyzed by modern historians.It baffled many readers, including Moritz Wagner, and it is no wonder that this confusion continues to this day. Vorzimmer (1965) once said, "Natural selection, as Darwin himself stated, is the name he gave to the process of speciation", and what else could Vorzimmer say!Darwin's ambiguity is all the more surprising since speciation is the most characteristic phenomenon of "horizontal" evolution, whereas natural selection is the driving force of "vertical" evolution.His Species is apparently titled "Natural Selection" and later published his manuscript under this title (1975, edited by Stauffer), while the title of the abridged 1859 edition (abbreviated ) is, again implying that the two terms (i.e. natural selection and speciation) are equivalent.As far as Darwin is concerned, speciation is clearly primarily an aspect of natural selection, as can also be seen from some of his replies to Wagner.

Before Darwin became an evolutionist, he supported Lyell's concept of a defined lifespan for each species (sudden onset, sudden death) although he found it difficult to understand the "introduction" of new species on continents.So when he discovered a second bird species of the three-toed ostrich in the Patagonian steppes of South America, he thought its origin must be due to "change not progressive": if a species occurs Change, that is due to success in one fell swoop. (Darwin, 1980, edited by Herbert). Not long after Darwin became an evolutionist, he not only explained the speciation process on islands, but he was also able to explain speciation on continents due to geographical barriers (such as oceans, rivers, mountains, deserts).In addition, he speculates that parts of the continent (such as South Africa) may well have undergone a phase of rapid subsidence during which they were temporarily transformed into archipelagos, thus providing the required isolation (107-108 ), until it then surfaced again.We now know from his notes how much he attached importance to the necessity of geographic isolation for speciation at that time.

Thus, when it was found that Darwin later wrote in "Natural Selection" (written 1856-1859) and (1858-1859) when he regressed, he was very surprised at the extent of his regress.At that time, he was very receptive to the sympatric speciation of many species on the mainland due to some ecological, habitual, seasonal or behavioral specialization.He applies this mechanism specifically to those species whose ranges overlap slightly or only touch each other (such distributions are now called neighborhoods).This situation is common, especially in the tropics, and is currently interpreted as the second contact zone of the original isolated species or the terminal species (zones of secondary contact).On the other hand, Darwin took it for granted that such distribution patterns are formed in situ (in situ). "I do not doubt that many species have been formed at different points of a perfectly continuous area, in which the physical conditions have gradually changed from one point to another in an almost entirely imperceptible manner" (Natural Selection 266).He also explained that he thought it possible that a certain variety formed at one end of the population chain, another at the other end, and finally an intermediate variety formed in the narrow region where the two main varieties meet. Since the two main varieties may occupy a larger area than the intermediate variety, in a strictly patterned manner, they will quickly outcompete the intermediate variety and make it extinct, thus creating a clear pattern between the two main varieties. The discontinuity (discontinuity) of speciation (process) will be completed.As he says (p. 111): "The smaller differences between varieties are subsumed into the larger differences between species" (see pp. 51-52, 114, 128). Darwin's basic failure was his failure to separate isolation into extrinsic geo-ecological barriers and intrinsic isolation mechanisms.A passage in his Variation (1868, II, 185) faithfully reflects this. "On the principle that man must keep his domestic varieties apart in the selection and improvement of them, it would be clearly advantageous to varieties in a state of nature if they could be kept unmixed (whether by sexual repulsion, or reciprocal sterility) , that is, it is beneficial to the beginning of planting."He completely ignores the fact that here he is dealing with two entirely different principles.Subspecies (races) of domesticated animals formed under strict spatial (microgeographical) isolation, and Darwin did not explain at all how genetic differences arise in nature and can cause sexual exclusion or reciprocal sterility. When two different varieties are housed together, members of the same variety prefer to mate with each other (isogamy, or isogamy).Darwin overlooked the same difficulty in listing such instances.He enumerates thirteen instances of this preferential mating which he thinks he has ever discovered (Natural Selection: 258).In fact, after careful analysis, there is not a single case to support this contention.After removing inappropriate instances (such as duplications outside the breeding season), each "variety" that segregated partly due to behavioral segregation clearly came from a previous stage of spatial segregation in which genetic isolation.Darwin didn't understand this point, because he didn't understand the role of ecological (nutritional) obstacles at that time, including the ecological obstacles caused by ice cap propulsion in the new epoch. It is true that Darwin's thinking underwent a drastic change between 1844 and 1856 when he began writing Natural Selection.When I tried to explore the reasons for Darwin's later reduced role in isolation (Mayr, 1959b) before discovering his Notes on Evolution, my analysis was partial and incomplete. At the time I attributed Darwin's skepticism to four factors: (1) His use of the term "variety" was ambiguous, both for individual variants and for subspecies (populations).He used the word "variety" 24 times in , 8 times referring to variants, 6 times referring to geographical populations, and 10 times being vague (both variants and populations may be understood); (2) His concept of morphological species (as opposed to his previous concept of biological species); (3) He often confuses the multiplication process of species with Phyletic evolution; (4) He attempted to find a Single-factor explanations (see natural selection oddly as an alternative to segregation rather than an adjunct). In addition to agreeing with the importance of these factors, Sulloway (1979) pointed out that there were four other events that had an impact on Darwin's thinking between 1844 and 1859: (1) Darwin's taxonomic research on barnacles, from which he discovered the shape (2) Darwin's strategic considerations in order to make his conclusions more palatable to his colleagues, which included treating (initial) species as competitors rather than reproductive isolates; (3) Darwin transferred his ideas (thoughts) from birds and mammals to invertebrates (including uniparental ones) and plants; (4) Darwin paid more attention and attention to the principle of divergence, which he believed to be Reasons for the diversity of higher taxonomic levels. These factors all contributed to Darwin's tendency to find some kind of "difference" in species (rather than being reproductively isolated) and to figure out that isolation is not required in order to be "different".So true geographic segregation would be unnecessary. Yet "a certain degree of Separation must be ... advantageous. This separation arises from a single selected individual and his offspring, once forming even slightly different varieties, tend to inhabit different places, in slightly There are different seasons of reproduction, and from the same variety selection isotypes" (Natural Selection; 257; 103).The model framework of his thought can be seen from the following passage: "If a variety flourishes and outnumbers its parent species, it may be classified as a species and the original parent species as a variety, or It may have replaced and exterminated the parent species, or both, both listed as separate species” (: 52).Some of Darwin's remarks suggesting sympatric speciation appear to be paraphrases (Paraphrases) of similar remarks in contemporary botanical literature (eg, Herbert, 1837).The influence of botanists on Darwin is not surprising, since Darwin probably had more contact with botanists than he did with zoologists in the 1840s and 1850s. Clearly, Darwin was indecisive or ambiguous about the actual role of isolation in speciation.In this regard, he is not alone. Owen commented: "Darwin said that isolation is an important part of the process of natural selection, but how can a thing be selected if it is isolated?" Of course, Darwin did not actually say this, but he did in nature Geographic speciation is discussed in the chapter on selection.Another reviewer, Hopkins, proposes a sympatric speciation by isomorphic mating: "If it can be shown that the more complete and robust individuals in each species mate with individuals like them for propagation, It must then be admitted that natural selection must exist as a cause of action." What has always puzzled Darwin's commentators is the question of interfertility between members of a species, including members of intraspecific varieties. How to become sterile.On this point, even Huxley and Darwin's other friends have been puzzled.Darwin responded to these criticisms by continually emphasizing the gradual transformation of varieties into species, but never presented convincing examples of the gradual process of geographical speciation. Although Darwin never completely abandoned the concept of geographic speciation, he put less emphasis on the issue in the sixth edition (1872) than in the first edition.His gradual decline in the importance of geographical species is also reflected in his correspondence with Wagner, Weismann, and SemPer.Darwin increasingly saw speciation as an adaptive process, an aspect of the principle of divergence that completely removed any relationship necessary to achieve reproductive isolation.As Ghiselin (1969) rightly points out: "There is no reliable evidence that when he wrote he had species in mind as reproductively isolated populations".Darwin's own field observations repeatedly pointed to him that Sea Islands were ideal places for the origin of new species, yet Darwin no longer considered how important spatial isolation was to the genetic composition of isolation mechanisms.It was this question that eventually led to a lengthy debate between him and Moritz Wasner (see Chapter 11). Darwin's main ideas about speciation and evolution were conceived in a few short years (1837-1839), although he continued to refine these ideas. In 1844 he was ready to write a long treatise of 230 pages in manuscript, including some of the points that were later published in .Darwin himself was well aware of the importance of the manuscript and told his wife to publish it if he died.However, he only dared to show his "subversive" document to one person, and that person was the botanist Joseph D. Hooker.It took another 15 years for Darwin to finally publish his masterpiece, a delay that would no doubt have continued had it not been for the events to be discussed below.Considering that the whole world was against evolution at the time, Darwin saw no need to rush to publish his views.However, he miscalculated the situation.The widespread circulation of Chambers' Remains showed him that interest in evolution was much higher than he had imagined, and also pointed out to him that there might be others who had independently come to similar conclusions.There was indeed such a person, and he was Wallace (Alfred Russel Wallace, 1823-1913). The accidental coincidence of another naturalist (meaning Wallace) offering an explanation of evolution very similar to Darwin's is something that has been astonishing since 1858.These two men are very different in many ways.Darwin was a very wealthy gentleman with many years of college education and a private research scholar who could devote his full time to research; Wallace was the son of a poor man with a lower middle-class social background (this was a very important factor in Victorian England), had no higher education, never had a lot of money, was always looking for a job to make ends meet, and spent long periods of time in the dangerous occupation of collecting birds and insects in the tropics where diseases were endemic .But they were identical in some crucial respects: they were both Englishmen, both had read Lyell and Malthus, both were naturalists, and both had undertaken naturalist expeditions in the tropical archipelago.Other aspects of Wallace will be explained later when he introduces how he independently discovered the principle (theory) of natural selection, but how he prompted Darwin to publish in advance must be introduced here. Wallace left school (junior high school) at the age of 13 to work as an assistant to his older brother (surveyor) and spent the next 7 years trekking in swamps and mountains.While engaged in surveying work, Zhonghua Laitu became a passionate natural history enthusiast. At first he collected only plants, but since befriending the dedicated entomologist Henry Walter Bates, he has added butterflies and beetles to his collection.He even loves reading more than Darwin, and the most important force that motivates him comes from books.Darwin's "Research Diary" and Humbert's "Self-Report" aroused the enthusiasm of these two young naturalists, and together they set off from England to the Amazon Basin in South America in April 1848. Their purpose was very clear, "to collect facts to settle the problem of the origin of species, as Wallace put it in a letter. It is a question we have often discussed or corresponded with since we read Chambers's "Remains" in the autumn of 1845" (Bates , 1863).The powerful tributaries of the Amazon divide the whole valley into many islands with forests, so that innumerable groups of species are distributed in neighborhoods as in archipelagos.When Wallace recalled this past more than 50 years later, he said: "Ever since I read "Remains" before I went to the Amazon basin, I have often been constantly thinking about the great secret of the specific steps by which each new species arises and how it adapts to its environment. I am convinced (every time) species) are the direct result of the transformation of pre-existing species through the normal process of generation, as claimed in "The Remains." Since Wallace was not an orthodox Christian, he compared Lyell and Agassi It is easier to accept the view of species evolution. How the facts of species distribution in the Amazon Trail helped Wallace refine his ideas we will never know. Four years later, when Wallace and Bates broke up and returned to England, the ship he was on caught fire and sank on the way (August 6, 1852), and all the specimens he collected and most of the diaries, notes and observations were also lost. fall.But he was also able, by recollection, to point out (1853) the distribution of each of a great many closely related species of apes, butterflies, and flightless birds, around the Amazon and its tributaries.Wallace was not discouraged by this unexpected event that almost completely lost the fruits of his four years of hard work in South America. He quickly planned a new expedition and carefully selected the Malay Archipelago as the most suitable species for research. region of origin (McKinney, 1972).He set off from England in early March 1854, and within a year (February 1855) he wrote a book entitled "Laws Controlling the Introduction of New Species". (On the Law Which Has Regulated the Introduction of New Species) This famous paper.In a letter he wrote to Bates (who no doubt discussed evolution with each other both in the Amazon and before): "For those who have not given much thought to the subject I feel that my The article on the succession of species (succession) will not really understand like you. Of course this article just puts forward the theory and does not develop the theory". What Wallace really wanted to do was to solve Lyell's "introduction" problem.We now know from his unpublished notes (McKinney, 1972) that as early as 1854 he had rejected Lyell's view that species varied only within definite limits and that the living world was a slow and And constantly changing.Although Wallace accepted Lamarck's theory of vertical evolution by denying that species were fixed, this did not solve the problem of rotation of extinct species.The introduction of new species is still an unsolved mystery, and unraveling this mystery is the task Wallace set to himself.This, as he clearly stated in his 1855 paper, was due to geography, that is to say, his examination of the distribution of species in the Amazon basin and the Malay archipelago provided him with the answer: "The most closely related species occur in the same area or closely adjoining regions...therefore the natural sequence of species according to their affinities is also geographical." This observation led him to the following law: that each species arose in relation to the pre-existing , closely related species are consistent in space and time.In speaking of "in the same area or in the immediate adjoining area" At that time, Wallace did not clearly specify the exact geographical location of the original species, but Wagner was more explicit on this point.However, if the sentence that a parent species differentiates into two or more offspring species is read backwards, the concepts of common ancestor and phylogenetic tree are automatically and naturally introduced.In short, Wallace boldly outlined a theory of evolution based on practical experience, that is, the distribution pattern of closely related species. Darwin and Wallace thus took an entirely new approach to evolution (albeit based on Lyell's), namely geographic evolutionism, which did not attempt to identify the origins of major groups of organisms or their differences in time. (Longitudinal) To solve the problem of the origin of biodiversity, compare the taxa in the same period, but compare the species taxa in the same period in the geographical dimension, that is, compare the populations and species that replace each other geographically way to solve it. How did the above paper published by Wallace in 1855 influence Darwin's thinking and actions?This problem will be introduced below. For 20 years after 1837 Darwin never mentioned evolution.At this time, he was concerned with the issue of species. In a letter to a friend, he stated that he would write a book about "the species" ("the species book").Can species change?Can one species transform into another?These are some specific questions that Darwin posed.In order to make a convincing answer, Darwin believed that a large amount of evidence must be collected.Didn't Lamarck and Chambers also ask the question of evolution without conversion? Considering that Darwin turned into an evolutionist in 1837 and conceived and outlined his theory of natural selection in September 1838, one would expect that he would publish this most important theory in biology as soon as possible.Yet he delayed it for twenty years and published it only by accident.Why did he delay for so long?There are many reasons for this. First, Darwin had to first complete his geological research, which had already been carried out and was part of the Beagle's expedition report.But when Darwin finished his undertaking in 1846, he turned to barnacles (cirripedes) and spent eight years without writing a "book of species".This inevitably raises many questions.First, was Darwin ready to write the "Book of Species" in 1846?The answer is obviously no, as he has repeatedly stated in his letters, and it can also be seen from his continuous collection of materials.Even some of his basic ideas were not mature, for example, his "principle of divergence" was only formed in the 1950s. The second question is, why did Darwin spend too much time studying barnacles instead of concentrating on collecting the missing materials in the "center of species"?After studying the situation at the time, I cannot help but suspect that Darwin was really afraid to express his views.The intellectual climate in England at the time was completely unfavorable to the acceptance of Darwin's theory. Chambers's "Remains", published in 1844, despite its deistic views, was gritted by all critics and wanted to burn the body to ashes.The famous British scientists at that time, including Darwin's good friends Leyle, Hooker and Huxley at that time, almost completely opposed the idea of ​​evolution.This is not, however, because evolution itself is so difficult to justify, but because of the purely materialistic explanation of natural selection. Gruber (1974) amply demonstrates how well Darwin realized that his theory would unleash a violent storm of damnation, indeed, as we shall see, in After publication, except Wallace, Hooker, and a few naturalists, almost no one in England accepted the explanation of natural selection. The third question is, why did Darwin spend so much time studying cirripedes, which do not seem to be so important?The answer to this question may have three meanings.First, Darwin apparently did not expect to take eight years when he began to work on the particular genus (barnacles) he had collected from Chile.However, since he had no other specific plans at this time, and found it convenient to study the relatives and distant relatives of animal kinship through barnacles, he planned to write a monograph on the whole barnacles based on the research results.In addition, Darwin considered that establishing his reputation as a systematician through this research would increase the weight of his opinion.He was later awarded the Royal Society's Copley Prize for this research, showing that he was right.Finally, he also realized that the study of barnacles contributed to his understanding of variation, comparative morphology, the concept of species and found that the geological record was incomplete.There is no doubt that Darwin's study of barnacles greatly enhanced his abilities and experience, as Ghiselin (1969) said: "This whole research work is nothing less than a rigorous and general review of the comprehensive theory of evolutionary biology. And the decisive test.” But Guo did not say why it took Darwin as long as 8 years for this research.On this point, people can only speculate that Darwin was stuck on a tiger, unable to stop.Of course, he would not have thought that this was the best way for him to gain experience at the beginning of this research. Looking back, it is certain that he has indeed benefited a lot from studying barnacles. Although Darwin published nothing on species in the 21 years between March 1837 (when he began to recognize speciation) and August 1858 (published in the Annals of the Linnean Society, see below), from his notes and Correspondence reveals that he has been haunted by the issue of species.Darwin knew well that the origin of species was the key to the question of evolution, yet he was still hesitant about the meaning of species and the process of speciation. By 1854 Darwin had largely finished his work on barnacles and devoted himself entirely to compiling his notes on the species.One would have expected that the publication of Wallace's paper "The Introduction of New Species" (1855) would have prompted Darwin to act, but this was not the case.Darwin did not respond to this pioneering paper until two years later, and again after Wallace wrote to him.He wrote back to Wallace on May 1, 1857: "It is clear to me that we think very much alike and to some extent come to similar conclusions... I agree almost entirely with your paper. Every word. . . . I am preparing my book for publication, but the title is too large . . . I don't think it will be published for two years" (L.L.D., 95-96). But there was one person who was greatly shocked after seeing Wallace's paper, and this person was Lyell.As recently as a lecture in 1851, he severely criticized any tolerance and concessions to the idea of ​​evolution.但是从1853年12月到1854年3月他为了研究火山活动访问了北非西北部的马德拉群岛和加那利群岛。他在这些地方亲身感受到Von Buch，达尔文以及其它一些博物学家以前所描述的景像，即每个海岛的动物物种分布的严格局限性。他在日记中写道：“马德拉群岛和格拉帕戈斯群岛很相似，每个岛屿和海礁都住有不同的物种”（Wilson，1970）。当他回到英国研究整理他所收集到的标本时于1855年12月26日读到华莱士的论文，华莱士助学说显然深深地触动了他。他立即着手就物种问题从所阅读的资料中摘录笔记并记下疑问。最后决定到达尔文的乡村居处进行访问并了解达尔文的研究工作情况。达尔文知道自己的观点是和莱伊尔的格格不入，因此便没有和他讨论物种起源问题（达尔文和胡克尔倒是常讨论这个问题）。 1856年4年16日达尔文就他的观点给莱伊尔写了一封长信。莱伊尔虽然似乎还并不全然理解，但他极力劝说达尔文尽早地将他的观点发表以免其它人捷足先登。由于使他迟疑的主要原因已经消除，达尔文便于一个月之后，在1856年5月开始撰写他的伟大的“物种的书”。 两年以后，1858年6月，达尔文完成了全书十五章初稿，正在这时突然发生了一件出乎达尔文意料的事。他收到了华莱士的一封信，并附有题为“变种与原种永远分离的趋势”（On theTendency of Varietie to Depart Indefintely from theOriginalType）一文的手稿。华莱士在信中写道如果达尔文认为这篇文章有足够的创见和价值，请他将之转给莱伊尔，据推测，是请莱伊尔推荐发表（华莱士的原信已遗失）。达尔文于6月18日将华莱土的手稿寄给莱伊尔并附有一信，信中说：“你说过的话已经出乎意料地成为现实，我本应当棋先一着的…我从来没有见到过比这更惊人的巧合；即使华莱士手头有我在1842年所写的手稿提要，他也不可能写出更好的摘要…所以我的一切优先权，无论它值多少，都彻底消失了。” 至于莱伊尔和胡克尔是怎样将华莱士的论文连同达尔文1844年论文的摘要和达尔文于1857年9月5日给Asa Gray的信一起于1858年7月1日提交伦敦的林奈学会的事已经成为众所周知的着名故事。附有上述文件的林奈学会年报于1858年8月20日出版。值得注意的是达尔文和华莱士在上述材料中都没有论证进化。他们谈到的主要是进化机制。达尔文是以对变种的形成的长篇讨论开始，华莱士则以生存竞争引起的自然平衡的讨论打头。 就华莱士的情况而言是很自然并合乎逻辑的，因为华莱士1858年的论文显然是他的1855年文章的延续，在后一篇（1855）文章中他坚定地站了出来拥护进化。 的出版 华莱士和达尔文提出通过自然选择的革命性进化学说的文章联合发表后竟然没有什么反应，这不能不使人感到诧异。林奈学会会长在1858年的会务报告中曾指出：“今年…确实没有什么使这门科学发生革命性变化的惊人发现。”然而鸟类学家AlfredNewton却是例外，他在30年后声称在这几篇文章中找到了一份解决成年累月困扰着他的问题的十分完善而又简明的答案（Newton，1888），他还劝说另一位鸟类学家H． B． Tristram（1859）运用自然选择来说明云雀（百灵鸟）的基地适应（substrate adaptation）。 由于一本大书的出版时间很长，莱伊尔和Hooker敦促达尔文写一篇简短的摘要在杂志上发表。达尔文于1858年7月到1859年3月写的这篇“摘要”长达490页，这就是一般称为的名着。虽然达尔文一直坚持认为这只是一份摘要，但在出版公司发行人John Murray的要求下他最后同意将“摘要”的字样从书名中删掉。这书于1859年12月24日出版，共125O册，很快就被批发商订购一空。随后的三版（于1860－1866先后出版）没有作重大修订，第五版（1869）稍有变动，最后一版（第六版，1872）增加了一章。在这一段时间中，达尔文正忙于其它工作，特别是他的植物学和行为学方面的研究，因而他自己也估计由干工作太忙不会再有增订版。他随后的着作，尤其是《人类及动物的表情》（The Expression of the Emotions inMan and Animals，1872）和《植物界的杂交和自花受粉》（The Effects of Cross and Self－Fertilization in the PlantKingdom，1876）是如此的出色和具有开拓性，因而有人曾经正确指出，即使他没有提出进化学说，这些着作连同他的珊瑚礁学说以及关于藤壶的专着也足以使达尔文名扬天下。有人曾扬言达尔文是因为被他的进化论的对手击败后才以这些研究作为掩护逃进避风港的，这纯粹是一派胡言。 常常有人提到下面的现象太不正常，即从来没有一位着名的动物学家（不论是生理学家、胚胎学家，还是细胞学家）对进化学说作出任何贡献，而且至少就19世纪来说，他们几乎全都歪曲了整个进化问题。有人还说，像达尔文和华莱士这样的两个“普通的业余爱好者”反倒解决了大问题！ 这种特殊现象可以有不同的答案，然而最简单的答案无疑是，生理学家、胚胎学家和绝大多数实验生物学家所研究的是功能性问题，只是很间接地才接触到进化。而博物学家则成天地面对着进化问题，毫无疑问这是他们最感兴趣也是最关心的；他们不断地关心这类问题也就毫无疑问地使他们比实验生物学家处于更有利的地位来提出恰当的问题并寻求答案。最后，达尔文和华莱士已不再是业余爱好者，而是受过高深训练的职业博物学家。 这就可以解释就进化问题而言为什么Bernard，Helmholtz和Hertwig这样一些着名的实验生物学家统统都失败了。但是却无法回答为什么Owen，von Baer，Ehrenberg，Leuckart，或19世纪其它的一些着名的系统学家，比较解剖学家都是鼠目寸光看不清问题的实质。他们之所以失败可能响很多原因。就Owen和阿伽西来说，毫无疑固是因为他们顽固地执着于另外的解释和概念体系；对像J．Muller，Leuckart等这样一些着名的德国动物学家而言则可能是对信口开河的“自然哲学派”的逆反心态。这些动物学家之所以缺乏思辩推论则和形态学理论以及个体发生的信息量有关。他们对比较大的问题不感兴趣。更重要的是，他们都不是真正的自然种群论者。