From Charles Darwin's botanical country-house studies to modern plant biology

As a student of theology at Cambridge University, Charles Darwin (1809–1882) attended the lectures of the botanist John S. Henslow (1796–1861). This instruction provided the basis for his life-long interest in plants as well as the species question. This was a major reason why in his book On the Origin of Species , which was published 150 years ago, Darwin explained his metaphorical phrase 'struggle for life' with respect to animals and plants. In this article, we review Darwin's botanical work with reference to the following topics: the struggle for existence in the vegetable kingdom with respect to the phytochrome-mediated shade avoidance response; the biology of flowers and Darwin's plant–insect co-evolution hypothesis; climbing plants and the discovery of action potentials; the power of movement in plants and Darwin's conflict with the German plant physiologist Julius Sachs; and light perception by growing grass coleoptiles with reference to the phototropins. Finally, we describe the establishment of the scientific discipline of Plant Biology that took place in the USA 80 years ago, and define this area of research with respect to Darwin's work on botany and the physiology of higher plants.     

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.     

Two new Mio-Pliocene Chadian hominids enlighten Charles Darwin's 1871 prediction

The idea of an evolutionary sequence for humans is quite recent. Over the last 150 years, we have discovered unexpected ancestors, numerous close relatives and our deep evolutionary roots in Africa. In the last decade, three Late Miocene hominids have been described, two about 6 Ma (Ardipithecus and Orrorin) in East Africa and the third dated to about 7 Ma (Sahelanthropus) in Central Africa. The specimens are too few to propose definite relationship to other species, but clearly these belong to a new evolutive grade distinct from Australopithecus and Homo. Moreover, all of them were probably habitual bipeds and lived in woodlands, thus falsifying the savannah hypothesis of human origins. In light of all this recent knowledge, Charles Darwin predicted correctly in 1871 that Africa is the birthplace of humans, chimpanzees and our close relatives.     

Sir Charles Edward Saunders, Dominion cerealist.

Charles Edward Saunders was born in London, Ontario, in 1867. His father, Sir William Saunders, was the first director of the Dominion Experimental Farms (1886-1911). Charles received his B.A. with honours in science from the University of Toronto in 1888 and his Ph.D. in chemistry from Johns Hopkins University in Baltimore, Maryland, in 1891. He attempted a career in music, his first love, from 1893 to 1902. With his father, Charles attended the 1902 International Conference on Plant Breeding and Hybridization in New York, where he learned of Mendel's theories of inheritance and their applicability to plant breeding. When he began work in 1903 in the Division of Cereal Breeding and Experimentation at the Central Experimental Farm in Ottawa, he used the knowledge he had gained at that conference. It was Charles's goal to achieve "fixity" in the varieties that had been bred and released using phenotypic mass selection, prior to his tenure as Cerealist. He selected four heads from the wheat variety Markham and in the winter of 1904 he performed a "chewing test" to select for gluten elasticity and colour. Seeds from two heads were chosen, and seeds from one went on to produce the variety Marquis after extensive yield trials on the Prairies. Marquis was 7 to 10 days earlier than Red Fife, the standard bread wheat of the Prairies. The earliness and tremendous yield of Marquis wheat resulted in the rapid and successful settlement of the Great Plains and countless billions of dollars in revenue to Canada. By 1923, 90% of the spring wheat in Canada and 70% in the USA was Marquis. Charles continued as Dominion Cerealist until his retirement in 1922. He was knighted in 1934, and died in 1937.     

Charles Darwin's correspondence with David Moore of Glasnevin on insectivorous plants and potatoes

Recently discovered correspondence between Charles Darwin and David Moore shows the latter's role in providing fresh material of importance to Darwin's studies on insectivorous plants. One letter relates to Moore's experimental work on potatoes. This research, probably concerned with resistance of selected varieties of potato to blight, is apparently not supported by Glasnevin Botanic Garden (Dublin) records or contemporary literature.     

Charles Darwin's theory of evolution: A review of our present understanding

The paper characterizes Darwin's theory, providing a synthesis of recent historical investigations in this area. Darwin's reading of Malthus led him to appreciate the importance of population pressures, and subsequently of natural selection, with the help of the wedge metaphor. But, in itself, natural selection did not furnish an adequate account of the origin of species, for which a principle of divergence was needed. Initially, Darwin attributed this to geographical isolation, but later, following his work on barnacles which underscored the significance of variation, and arising from his work on botanical arithmetic, he supposed that diversity allowed more places to be occupied in a given region. So isolation was not regarded as essential. Large regions with intense competition, and with ample variation spread by blending, would facilitate speciation. The notion of place was different from niche, and it is questioned whether Darwin's views on ecology were as modern as is commonly supposed. Two notions of struggle are found in Darwin's theory; and three notions of variation. Criticisms of his theory led him to emphasize the importance of variation over a range of forms. Hence the theory was populational rather than typological. The theory required a Lamarckian notion of inheritable changes initiated by the environment as a source of variation. Also, Darwin deployed a use/habit theory; and the notion of sexual selection. Selection normally acted at the level of the individual, though kin selection was possible. Group selection was hinted at for man. Darwin's thinking (and also the exposition of his theory) was generally guided by the domestic-organism analogy, which satisfied his methodological requirement of a vera causa principle.     

达尔文对遗传学的贡献

简要介绍了达尔文对遗传学所做出的重要贡献。主要包括3个方面:1)收集整理了大量的生物遗传变异的资料,并提出了若干重要的论点;2)创立了发育的遗传理论——泛生论,对后来的遗传理论(尤其是德弗里斯,高尔顿和魏思曼的遗传理论)产生了重要影响;3)提出了遗传物质分子载体的概念——芽球,可以看作是基因概念的雏形。     

Multilocus genotypes from Charles Darwin's finches: biodiversity lost since the voyage of the Beagle

Genetic analysis of museum specimens offers a direct window into a past that can predate the loss of extinct forms. We genotyped 18 Galápagos finches collected by Charles Darwin and companions during the voyage of the Beagle in 1835, and 22 specimens collected in 1901. Our goals were to determine if significant genetic diversity has been lost since the Beagle voyage and to determine the genetic source of specimens for which the collection locale was not recorded. Using ‘ancient’ DNA techniques, we quantified variation at 14 autosomal microsatellite loci. Assignment tests showed several museum specimens genetically matched recently field-sampled birds from their island of origin. Some were misclassified or were difficult to classify. Darwin''s exceptionally large ground finches (Geospiza magnirostris) from Floreana and San Cristóbal were genetically distinct from several other currently existing populations. Sharp-beaked ground finches (Geospiza difficilis) from Floreana and Isabela were also genetically distinct. These four populations are currently extinct, yet they were more genetically distinct from congeners than many other species of Darwin''s finches are from each other. We conclude that a significant amount of the finch biodiversity observed and collected by Darwin has been lost since the voyage of the Beagle.