Darwin Studies Research Articles

Genetic architecture and evolution of the S locus supergene in Primula vulgaris.

Darwin's studies on heterostyly in Primula described two floral morphs, pin and thrum, with reciprocal anther and stigma heights that promote insect-mediated cross-pollination. This key innovation evolved independently in several angiosperm families. Subsequent studies on heterostyly in Primula contributed to the foundation of modern genetic theory and the neo-Darwinian synthesis. The established genetic model for Primula heterostyly involves a diallelic S locus comprising several genes, with rare recombination events that result in self-fertile homostyle flowers with anthers and stigma at the same height. Here we reveal the S locus supergene as a tightly linked cluster of thrum-specific genes that are absent in pins. We show that thrums are hemizygous not heterozygous for the S locus, which suggests that homostyles do not arise by recombination between S locus haplotypes as previously proposed. Duplication of a floral homeotic gene 51.7 million years (Myr) ago, followed by its neofunctionalization, created the current S locus assemblage which led to floral heteromorphy in Primula. Our findings provide new insights into the structure, function and evolution of this archetypal supergene.

“What a Painfully Interesting Subject”: Charles Darwin's Studies of Potato Late Blight

“What a Painfully Interesting Subject”: Charles Darwin's Studies of Potato Late Blight

The Effect of Multiple Intelligences Theory-Based Education on Academic Achievement: A Meta-Analytic Review

The questions of what intelligence is and how it is defined are issues that have occupied mankind for centuries (Selcuk, 2005). As studies on human intelligence had gained great momentum by the end of the 19th century, this led to the emergence of various theories on the issue (Denig, 2004). The first studies on intelligence can be said to be Darwin's studies on animal intelligence, and his nephew Galton's studies on human intelligence (Boring, 1950). At the beginning of the 20th century, Binet and Simon in particular made significant contributions to the understanding of human intelligence (Armstrong, 2000; Gardner, 1993a). Also, the studies of Spearman and Thurstone brought great innovations and expansions to the understanding of intelligence itself (Bumen, 2005). Traditionally, intelligence has been widely accepted by psychologists as a general intelligence, and it has been defined as a general capacity for conceptualization and problem solving that can be measured through IQ tests (Visser, Ashton, & Vernon, 2006). The concept of intelligence took its first step with Binet's implementation of IQ tests (Zazzo, 1993). Since then, many intelligence tests have appeared mostly measuring verbal memory, verbal reasoning, numerical reasoning, understanding of logical sequences, and ability to state how one would solve every-day problems (Gardner, 1999). However, the concepts of intelligence and IQ gained a different dimension with the publication of Howard Gardner's (1993a) inspirational book Frames of Mind: The Theory of Multiple Intelligences in 1983. Rather than defining intelligence in terms of mental test results or IQ scores, Gardner defined intelligence as a psychobiological information processing capacity to solve problems or fashion products that are valued in at least one community and culture (Kornhaber, Fierros, & Veenema, 2004). After years of study and observation on gifted and handicapped children, Gardner (1999) concluded that the mental potential of a human does not consist of a single intelligence but of multiple intelligences processed autonomously and localized in different parts of the brain. In his theory of multiple intelligences (MIT), Gardner (1993a) argues for a pluralistic view of the brain rather than a single part responsible for many functions. Also, according to MIT, the human brain has multiple sections, each functioning independently to modify our life. However, when we also attend to a complex task, these units engage their power and work in great harmony (Gardner, 1993 a).Meanwhile, after Gardner's (1993b) Frames of Mind: The Theory into Practice was published, the understanding that was brought to intelligence was transformed into applications. MIT emerged to become popular in the field of educational sciences after 1998, with various studies conducted on the issue (e.g., Bacbay, 2000; Bumen, 2001; Cockungonullu, 1998; Demirel et al., 1998; Talu, 1999; Tarman, 1999). Furthermore, aside from all the literature and results supporting this theory, some criticisms are also seen to have been made on the theory itself. One of the main points of these criticisms is whether the eight potentials, which are accepted as modalities of intelligence in the theory, form abilities or mental domains (White & Breen, 1998). It has also been stated that, while MIT is consistent with much empirical evidence, it has not been subjected to strong experimental tests (Denig, 2004). MIT is considered to be too broad to be useful for planning curriculum, as well as that it presents a static view of student competence (Klein, 1997). However, although there are some criticisms about MIT, very few theories in the scope of education have been said to create such a significant impact as MIT has done on teaching and learning (Saban, 2009; Shearer, 2004).Multiple Intelligences TheoryAs a neuropsychology and development specialist, Gardner started to analyze the cognitive capacity of individuals in the 1970s and 80s after analyzing the traditional concept of intelligence. …

FROM SECRET AGENTS TO INTERAGENCY

ABSTRACTSome scientists who study animals have emphasized the need to focus on the “point of view” of the animals they are studying. This methodological shift has led to animals being credited with much more agency than is warranted. However, as critics suggest, on the one hand, the “perspective” of another being rests mostly upon “sympathetic projection,” and may be difficult to apply to unfamiliar beings, such as bees or even flowers. On the other hand, the very notion of agency still conveys its classic understanding as intentional, rational, and premeditated, and is still embedded in humanist and Christian conceptions of human exceptionalism. This paper seeks, in the first part, to investigate the practical link between these two notions and the problems they raise. In the second part, following the work of two historians of science who have revisited Darwin's studies of orchids and their pollinators, it will observe a shift in the meaning of the concept of agency. Indeed, creatures may appear as “secret agents” as long as we adopt a conventional definition of agency based on subjective experience and autonomous intention. However, when reframed in the terms of “agencement” — an assemblage that produces “agentivity” — agency seems to be much more extensively shared in the living world. We will then explore some of the concrete situations in which these agencements are manifested, and through which creatures of different species become, one for another and one with another, companion‐agents.

History of Ecological Sciences, Part 37: Charles Darwin's Voyage on the Beagle

History of Ecological Sciences, Part 37: Charles Darwin's Voyage on the Beagle

Minute observations and theoretical framework of Darwin's studies on climbing plants

The role of movement in plants was unrecognised for a long time, due to the relative slowness of such movements by comparison with those of active animals such as insects and vertebrates, and to the difficulty with which they are distinguished from mere growth processes. Given this, the pioneer work of Darwin ( On the Movements and Habits of Climbing Plants 1865) is a milestone in botany. It is always cited as the beginning of any rigorous analysis of plant movement. Such a successful approach results at once from Darwin's broad knowledge of natural history, his use of numerous direct observations and simple experiments, but also from his own talent, which compensated for technical gaps in several instances. His use of metaphorical descriptions was a response to the lack of a firm theoretical background. It facilitated a preliminary classification of plant movement and a comparison of observations. Perhaps his most fruitful metaphors were those drawn from economic concepts, such as division of labour. Darwin's legacy in plant physiology is impressive, as even the most recent biophysical interpretations of climbing plants (e.g. tendril perversion) take place inside the framework he constructed.

The legacy of Darwin's studies of floral adaptation and plant mating

The legacy of Darwin's studies of floral adaptation and plant mating

A new look at variation in Darwin's species of acorn barnacles

Darwin's studies on barnacles, begun to satisfy his curiosity about specimens from the Beagle, but later extended to the large collections of other naturalists, lasted for 8 years and produced a set of definitive monographs. Darwin was particularly troubled over the taxonomy of two groups of acorn barnacles, Balanus tintinnabulum and B. amphitrite, which he ultimately classified as clusters of wellmarked varieties. Recent studies, based on established taxonomic methods or on statistical treatment of morphometric data, suggest these are clusters of full species and that the ‘intermediate’ forms are just phenotypic variants. Darwin was also troubled by the small chthamalid intertidal barnacles, which he eventually grouped as varieties of a world-wide species, Chthamalus stellatur. Gel electrophoresis and morphometrics now show this to be a heterogenous assemblage of distinct species, some very different, others closer together, all with restricted geographical range, but all showing extreme variability in the characters normally used for classification. Darwin's difficulties with the classification of the highly varying barnacles, and his anatomical studies on these peculiar animals, must have had considerable influence on the development of his theories about natural selection, more than is usually acknowledged by writers on evolution. These ‘lost years’ were in fact a period of intense zoological enquiry, and Darwin's change in attitude with regard to species and variation in nature underwent a big change, as can be seen from the letters and from the differences between the early drafts written before the barnacle work and the later Natural Selection and The Origin. Whether we regard the difficult groups of Balanus as clusters of species or clusters of varieties, they still draw attention to evolutionary processes as in Darwin's day.

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.