Challenges and opportunities for biogeography—What can we still learn from von Humboldt?

Alexander von Humboldt was arguably the most influential scientist of his day. Although his fame has since lessened relative to some of his contemporaries, we argue that his influence remains strong—mainly because his approach to science inspired others and was instrumental in furthering other scientific disciplines (such as evolution, through Darwin, and conservation science, through Muir)—and that he changed the way that large areas of science are done and communicated. Indeed, he has been called the father of a range of fields, including environmental science, earth system science, plant geography, ecology and conservation. His approach was characterized by making connections between non‐living and living nature (including humans), based on interdisciplinary thinking and informed by large amounts of data from systematic, accurate measurements in a geographical framework. Although his approach largely lacked an evolutionary perspective, he was fundamental to creating the circumstances for Darwin and Wallace to advance evolutionary science. He devoted considerable effort illustrating, communicating and popularizing science, centred on the excitement of pure science. In biogeography, his influence remains strong, including in relating climate to species distributions (e.g. biomes and latitudinal and elevational gradients) and in the use of remote sensing and species distribution modelling in macroecology. However, some key aspects of his approach have faded, particularly as science fragmented into specific disciplines and became more reductionist. We argue that asking questions in a more Humboldtian way is important for addressing current global challenges. This is well‐exemplified by researching links between geodiversity and biodiversity. Progress on this can be made by (a) systematic data collection to improve our knowledge of biodiversity and geodiversity around the world; (b) improving our understanding of the linkages between biodiversity and geodiversity; and (c) developing our understanding of the interactions of geological, biological, ecological, environmental and evolutionary processes in biogeography.     

Charles Darwin's debt to malthus and Edward Blyth

Conclusion It is not justifiable to accuse Darwin of conscious or unconscious plagiarism. This charge is contrary to the historical evidence and to the extensive information that we have about his character. When Darwin listed the writers on the origin of species by natural selection before himself, he did not mention Blyth, and this omission did not disturb the cordial relations between Darwin and Blyth. Blyth continued to supply Darwin with information which Darwin used in his later publications with due acknowledgment to Blyth. For example, in The Descent of Man, Darwin cited Blyth: Mr. Blyth, as he informs me, saw Indian crows feeding two or three of their companions which were blind.⁶³ Blyth felt no resentment. If he did, he would have so informed Darwin. Blyth did not regard himself as in any sense a predecessor of Darwin and he certainly did not resent Darwin as a plagiarizer of himself. Moreover, Darwin went to a great deal of trouble to find his own predecessors and to give them proper credit.⁶⁴ After Darwin had completed his work on natural selection, he wrote a letter to the Reverend Baden Powell in which he clearly showed recognition of the contribution of others to his own work:No educated person, not even the most ignorant, could suppose I mean to arrogate to myself the origination of the doctrine that species had not been independently created. The only novelty in my work is the attempt to explain how species became modified, and to a certain extent how the theory of descent explains certain large classes of facts; and in these respects I received no assistance from my predecessors.⁶⁵ *** DIRECT SUPPORT *** A8402011 00002     

Darwin Day in deep time: promoting evolutionary science through paleontology

Charles Darwin’s birthday, February 12th, is an international celebration coined Darwin Day. During the week of his birthday, universities, museums, and science-oriented organizations worldwide host events that celebrate Darwin’s scientific achievements in evolutionary biology. The University of Tennessee, Knoxville (UT) has one of the longest running celebrations in the nation, with 2016 marking the 19th year. For 2016, the theme for our weeklong series of events was paleontology, chosen to celebrate new research in the field and to highlight the specific misconceptions of evolution within the context of geologic time. We provide insight into the workings of one of our largest and most successful Darwin Day celebration to date, so that other institutions might also be able to host their own rewarding Darwin Day events in the future.     

The Darwin of pangenesis

The Darwin of pangenesis is very much another Darwin. Pangenesis is Darwin's comprehensive theory of generation, his theory about all sexual and asexual modes of reproduction and growth. He never explicitly integrated pangenesis with his theory of natural selection. He first formulated pangenesis in the 1840s and integrated it with the physiology, including the cytology, of that era. It was, therefore, not consilient with the newer cytology of the 1860s when he published it in 1868. By reflecting on the role of pangenesis in Darwin's life and work, we can learn to take a wider view of his most general theorising about animal and plant life.     

The Gentleman and the Rogue: The Collaboration Between Charles Darwin and Carl Vogt

This paper investigates the relationship between the eminent 19th-century naturalists Charles Darwin and Carl Vogt. On two separate occasions, Vogt asked Darwin for permission to translate some of the latter’s books into German, and in both cases Darwin refused. It has generally been assumed that Darwin turned down Vogt as a translator because of the latter’s reputation as a radical libertine who was extremely outspoken in his defence of scientific materialism and atheism. However, this explanation does not fit the facts, since, on closer investigation, Darwin not only gave serious consideration to engaging Vogt as the German translator of two of his books, albeit ultimately rejecting him, but he also collaborated with Vogt on the French editions of his works. In this paper we argue that this was not because Darwin was unaware of Vogt’s personality and blunt writing style; rather, Darwin seems to have decided that the benefits he would gain from their association would clearly outweigh the risk of offending some of his readers: in working with Vogt, who was not only a knowledgeable scientist but also an avowed adherent of Darwinism, Darwin could be assured of the scientific quality of the translation and of an edition that would not distort his central concepts – both of which were by no means matters of course in 19th-century translations of scientific works.     

Charles Darwin's views of classification in theory and practice

It has long been argued that Charles Darwin was the founder of the school of "evolutionary taxonomy" of the Modern Synthesis and, accordingly, that he recognized genealogy and similarity as dual, synergistic criteria for classification. This view is based on three questionable interpretations: first, of isolated passages in the 13th chapter of the Origin of Species; second, of one phrase in a letter that Darwin wrote about the work of an author he had partly misunderstood; and third, of his taxonomic practice in the barnacle monographs, which only implicitly embody his philosophy of classification, if at all. These works, seen in fuller context and with the perspective of extensive correspondence, are consistent with the view that Darwin advocated only genealogy as the basis of classification, and that similarity was merely a tool for discovering evolutionary relationships. Darwin was neither a Mayrian taxonomist nor a cladist, and he did not approach systematic issues in the same terms that we do in the late 20th century.     

Darwin was right: inbreeding depression on male fertility in the Darwin family

Charles Darwin, who was married to his first cousin Emma Wedgwood, was the first experimentalist to demonstrate the adverse effects of inbreeding. He documented the deleterious consequences of self‐fertilization on progeny in numerous plant species, and this research led him to suspect that the health problems of his 10 children, who were very often ill, might have been a consequence of his marriage to his first cousin. Because Darwin's concerns regarding the consequences of cousin marriage on his children even nowadays are considered controversial, we analyzed the potential effects of inbreeding on fertility in 30 marriages of the Darwin–Wedgwood dynasty, including the marriages of Darwin's children, which correspond to the offspring of four cousin marriages and three marriages between unrelated individuals. Analysis of the number of children per woman through zero‐inflated regression models showed a significantly adverse effect of the husband inbreeding coefficient on family size. Furthermore, a statistically significant adverse effect of the husband inbreeding coefficient on reproductive period duration was also detected. To our knowledge, this is the first time that inbreeding depression on male fertility has been detected in humans. Because Darwin's sons had fewer children in comparison to non‐inbred men of the dynasty, our findings give empirical support to Darwin's concerns on the consequences of consanguineous marriage in his own progeny. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 474–483.     

Darwin's principles of divergence and natural selection: Why Fodor was almost right

Darwin maintained that the principles of natural selection and divergence were the “keystones” of his theory. He introduced the principle of divergence to explain a fundamental feature of living nature: that organisms cluster into hierarchical groups, so as to be classifiable in the Linnaean taxonomic categories of variety, species, genus, and so on. Darwin’s formulation of the principle of divergence, however, induces many perplexities. In his Autobiography, he claimed that he had neglected the problem of divergence in his Essay of 1844 and only solved it in a flash during a carriage ride in the 1850s; yet he does seem to have stated the problem in the Essay and provided the solution. This initial conundrum sets three questions I wish to pursue in this essay: (1) What is the relationship of the principle of divergence to that of natural selection? Is it independent of selection, derivative of selection, or a type of selection, perhaps comparable to sexual selection? (2) What is the advantage of divergence that the principle implies—that is, why is increased divergence beneficial in the struggle for life? And (3) What led Darwin to believe he had discovered the principle only in the 1850s? The resolution of these questions has implications for Darwin’s other principle, natural selection, and permits us to readjust the common judgment made about Jerry Fodor’s screed against that latter principle.     

What would have happened if Darwin had known Mendel (or Mendel's work)?

The question posed by the title is usually answered by saying that the "synthesis" between the theory of evolution by natural selection and classical genetics, which took place in 1930s-40s, would have taken place much earlier if Darwin had been aware of Mendel and his work. What is more, it nearly happened: it would have been enough if Darwin had cut the pages of the offprint of Mendel's work that was in his library and read them! Or, if Mendel had come across Darwin in London or paid him a visit at his house in the outskirts! (on occasion of Mendel's trip in 1862 to that city). The aim of the present paper is to provide elements for quite a different answer, based on further historical evidence, especially on Mendel's works, some of which mention Darwins's studies.     

Darwin on Aristotle

Charles Darwin's famous 1882 letter, in response to a gift by his friend, William Ogle of Ogle's recent translation of Aristotle's Parts of Animals, in which Darwin remarks that his “two gods,” Linnaeus and Cuvier, were “mere school-boys to old Aristotle,” has been thought to be only an extravagantly worded gesture of politeness. However, a close examination of this and other Darwin letters, and of references to Aristotle in Darwin's earlier work, shows that the famous letter was written several weeks after a first, polite letter of thanks, and was carefully formulated and literally meant. Indeed, it reflected an authentic, and substantial, increase in Darwin's already high respect for Aristotle, as a result of a careful reading both of Ogle's Introduction and of more or less the portion of Ogle's translation which Darwin says he has read. Aristotle's promotion to the pantheon, as an examination of the basis for Darwin's admiration of Linnaeus and Cuvier suggests, was most likely the result specifically of Darwin's late discovery that the man he already knew as “one of the greatest ... observers that ever lived” (1879) was also the ancient equivalent both of the great modern systematist and of the great modern advocate of comparative functional explanation. It may also have reflected some real insight on Darwin's part into the teleological aspect of Aristotle's thought, indeed more insight than Ogle himself had achieved, as a portion of their correspondence reveals. This revised version was published online in July 2006 with corrections to the Cover Date.     

The origin of Darwin’s “abominable mystery”

The phrase “Darwin’s abominable mystery” is frequently used with reference to a range of outstanding questions about the evolution of the plant group today known as the angiosperms. Here, I seek to more fully understand what prompted Darwin to coin the phrase in 1879, and the meaning he attached to it, by surveying the systematics, paleobotanical records, and phylogenetic hypotheses of his time. In the light of this historical research, I argue that Darwin was referring to the origin only of a subset of what are today called angiosperms: a (now obsolete) group equivalent to the “dicotyledons” of the Hooker and Bentham system. To Darwin and his contemporaries, the dicotyledons’ fossil record began abruptly and with great diversity in the Cretaceous, whereas the gymnosperms and monocotyledons were thought to have fossil records dating back to the Carboniferous or beyond. Based on their morphology, the dicotyledons were widely seen by botanists in Darwin’s time (unlike today) as more similar to the gymnosperms than to the monocotyledons. Thus, morphology seemed to point to gymnosperm progenitors of dicotyledons, but this hypothesis made the monocotyledons, given their (at the time) apparently longer fossil record, difficult to place. Darwin had friendly disagreements about the mystery of the dicotyledons’ abrupt appearance in the fossil record with others who thought that their evolution must have been more rapid than his own gradualism would allow. But the mystery may have been made “abominable” to him because it was seen by some contemporary paleobotanists, most notably William Carruthers, the Keeper of Botany at the British Museum, as evidence for divine intervention in the history of life. Subsequent developments in plant systematics and paleobotany after 1879 meant that Darwin’s letter was widely understood to be referring to the abrupt appearance of all angiosperms when it was published in 1903, a meaning that has been attached to it ever since.     

Towards a postmodern synthesis of evolutionary biology

In 2009, we are celebrating the 200th anniversary of Charles Darwin and the 150th jubilee of his masterpiece, the Origin of Species. Darwin constructed the first coherent and compelling narrative of biological evolution and thus founded evolutionary biology—and modern biology in general, remembering the famous dictum of Dobzhansky. It is, however, counter-productive, and ultimately, a disservice to Darwin’s legacy, to define modern evolutionary biology as neo-Darwinism. The current picture of evolution, informed by results of comparative genomics and systems biology, is by far more complex than that presented in the Origin of Species, so that Darwinian principles, including natural selection, are incorporated into the evolving new synthesis as important but certainly not all-embracing tenets. This expansion of evolutionary biology does not denigrate Darwin in the least but rather emphasizes the fertility of his ideas.     

Engaging with Lyell: Alfred Russel Wallace’s Sarawak Law and Ternate papers as reactions to Charles Lyell’s Principles of Geology

Alfred Russel Wallace (1823–1913) and Charles Darwin (1809–1882) are honored as the founders of modern evolutionary biology. Accordingly, much attention has focused on their relationship, from their independent development of the principle of natural selection to the receipt by Darwin of Wallace’s essay from Ternate in the spring of 1858, and the subsequent reading of the Wallace and Darwin papers at the Linnean Society on 1 July 1858. In the events of 1858 Wallace and Darwin are typically seen as central players, with Darwin’s friends Charles Lyell (1797–1875) and Joseph Dalton Hooker (1817–1911) playing supporting roles. This narrative has resulted in an under-appreciation of a more central role for Charles Lyell as both Wallace’s inspiration and foil. The extensive anti-transmutation arguments in Lyell’s landmark Principles of Geology were taken as the definitive statement on the subject. Wallace, in his quest to solve the mystery of species origins, engaged with Lyell’s arguments in his private field notebooks in a way that is concordant with his engagement with Lyell in the 1855 and 1858 papers. I show that Lyell was the object of Wallace’s Sarawak Law and Ternate papers through a consideration of the circumstances that led Wallace to send his Ternate paper to Darwin, together with an analysis of the material that Wallace drew upon from the Principles. In this view Darwin was, ironically, intended for a supporting role in mediating Wallace’s attempted dialog with Lyell.     

Unearthening Old Data: Darwin was Indeed Correct About Earthworm Behavior

Charles Darwin is well known for his studies on the expression of emotions in animals and humans and as founding father of the concept of sexual selection. Yet it is commonly believed that the various arguments Darwin developed about behavior were usually illustrated only by anecdotes and observations recounted by explorers, naturalists, or zookeepers, and lacking any experimental approach. Here we show that this is not true. In his last book, The Formation of Vegetable Mould Through the Action of Worms (1881), Darwin mentions a series of meticulous experiments he ran to test his hypotheses about why earthworms plug their burrows and comes to the conclusion that earthworms seem to act in an intelligent way. His study can still function as a prime example of how to design an experiment for testing hypotheses. Only one part was missing in Darwin’s research: statistical analyses. We retrieved his data and analyzed them statistically. Based on these results, we cannot reject his conclusion as the statistical analyses confirmed Darwin was right. This shows that Charles Darwin already used a hypothetico-deductive approach, and he can thus be seen as the first true behavioral ecologist—a representative of a discipline that has been recognized for only about a hundred years.     

Darwin,Wallace, and Huxley,and Vestiges of the Natural History of Creation

Conclusion Publication of the Vestiges and the rather primitive theory of evolution it expounded thus played a significant role in the careers of Darwin and Wallace. In addition, in spite of his poor opinion of the Vestiges, it presented Huxley with a convenient topic for critical discussion and the opportunity to focus more attention on the subject of evolution. The dynamic interactions among these leading figures of nineteenth-century natural science helped spur the development of more sophisticated models of evolution.Darwin had a proper appreciation of Chambers's contribution to evolutionary thought, although he fully recognized the shortcomings of this work. He understood the importance of allowing fresh ideas about organic change to be ventilated. However, he was primarily concerned with his own theory and viewed all developments in evolutionary biology from this perspective. If he did not give full consideration to Chambers and his book early on, it was due mainly to his feeling that the concepts in the Vestiges were very different from his own; he was therefore reluctant to embrace them as the forerunners of his own theory. As a scholar, he was also troubled by the scientific errors in the book. However, the record demonstrates that he attempted to make amends for any oversight on his part. His generous letter to Chambers's daughter, and his gracious treatment of Chambers during the brief time the latter lived in London, are ample proof of that.The attacks of Huxley, Sedgwick, and other prominent natural historians and geologists at the time, the problems inherent in Chambers's evolutionary theory, and the publication of the Origin, are the major reasons why the Vestiges became a neglected work. Nevertheless, Chambers's contribution will always stand out because, together with those of other late eighteenth- and early nineteenth-century predecessors of Darwin, it laid the foundations of modern evolutionary thought and, more importantly, helped prepare the scientific community for the more fully developed ideas of Darwin and Wallace.     

Speaking volumes

Many have pondered the potential impact of Mendel's work if Darwin had come across it in his lifetime. Darwin found difficulty with a blending inheritance and natural selection but a new letter suggests he was grappling with a more modern view. Nigel Williams reports.     

Why anisogamy drives ancestral sex roles

There is a clear tendency in nature for males to compete more strongly for fertilizations than females, yet the ultimate reasons for this are still unclear. Many researchers—dating back to Darwin and Bateman—have argued that the difference is ultimately driven by the fact that males (by definition) produce smaller and more numerous gametes than females. However, this view has recently been challenged, and a formal validation of the link between anisogamy and sex roles has been lacking. Here, we develop mathematical models that validate the intuition of Darwin and Bateman, showing that there is a very simple and general reason why unequal gamete numbers result in unequal investment in sexually competitive traits. This asymmetry does not require multiple mating by either sex, and covers traits such as mate searching, where the male bias has been difficult to explain. Furthermore, our models show males and females are predicted to diverge more strongly when the fertilization probability of each female gamete is high. Sex roles thus ultimately trace back to anisogamy and the resulting consequences for the fertilization process.