Century-old Hypothesis Research Articles

Genetic architecture facilitates then constrains adaptation in a host–parasite coevolutionary arms race

In coevolutionary arms races, interacting species impose selection on each other, generating reciprocal adaptations and counter adaptations. This process is typically enhanced by genetic recombination and heterozygosity, but these sources of evolutionary novelty may be secondarily lost when uniparental inheritance evolves to ensure the integrity of sex-linked adaptations. We demonstrate that host-specific egg mimicry in the African cuckoo finch Anomalospiza imberbis is maternally inherited, confirming the validity of an almost century-old hypothesis. We further show that maternal inheritance not only underpins the mimicry of different host species but also additional mimetic diversification that approximates the range of polymorphic egg “signatures” that have evolved within host species as an escalated defense against parasitism. Thus, maternal inheritance has enabled the evolution and maintenance of nested levels of mimetic specialization in a single parasitic species. However, maternal inheritance and the lack of sexual recombination likely disadvantage cuckoo finches by stifling further adaptation in the ongoing arms races with their individual hosts, which we show have retained biparental inheritance of egg phenotypes. The inability to generate novel genetic combinations likely prevents cuckoo finches from mimicking certain host phenotypes that are currently favored by selection (e.g., the olive-green colored eggs laid by some tawny-flanked prinia, Prinia subflava, females). This illustrates an important cost of coding coevolved adaptations on the nonrecombining sex chromosome, which may impede further coevolutionary change by effectively reversing the advantages of sexual reproduction in antagonistic coevolution proposed by the Red Queen hypothesis.

New Light on theHistoria Augusta

AbstractThis paper presents a new manuscript of part of theHistoria Augustafrom Erlangen, which vindicates a more than century-old hypothesis by E. Patzig: that the 1489 Venice edition of the work is textually valuable. On this basis, and building on the recent work of R. Modonutti, I present five new passages that are not printed in modern editions of theHA, six lacunose passages restored, and propose that the lost Murbach manuscript is the source. Armed with this new evidence, I re-examine the question of the great lacuna between theLives of Maximus and Balbinusand theLives of the Two Valerians, showing that it is a codicological — and not authorial — feature.

New perspective of fracture mechanics inspired by gap test with crack-parallel compression

The line crack models, including linear elastic fracture mechanics (LEFM), cohesive crack model (CCM), and extended finite element method (XFEM), rest on the century-old hypothesis of constancy of materials' fracture energy. However, the type of fracture test presented here, named the gap test, reveals that, in concrete and probably all quasibrittle materials, including coarse-grained ceramics, rocks, stiff foams, fiber composites, wood, and sea ice, the effective mode I fracture energy depends strongly on the crack-parallel normal stress, in-plane or out-of-plane. This stress can double the fracture energy or reduce it to zero. Why hasn't this been detected earlier? Because the crack-parallel stress in all standard fracture specimens is negligible, and is, anyway, unaccountable by line crack models. To simulate this phenomenon by finite elements (FE), the fracture process zone must have a finite width, and must be characterized by a realistic tensorial softening damage model whose vectorial constitutive law captures oriented mesoscale frictional slip, microcrack opening, and splitting with microbuckling. This is best accomplished by the FE crack band model which, when coupled with microplane model M7, fits the test results satisfactorily. The lattice discrete particle model also works. However, the scalar stress-displacement softening law of CCM and tensorial models with a single-parameter damage law are inadequate. The experiment is proposed as a standard. It represents a simple modification of the three-point-bend test in which both the bending and crack-parallel compression are statically determinate. Finally, a perspective of various far-reaching consequences and limitations of CCM, LEFM, and XFEM is discussed.

Predicting Division Planes of Three-Dimensional Cells by Soap-Film Minimization.

One key aspect of cell division in multicellular organisms is the orientation of the division plane. Proper division plane establishment contributes to normal plant body organization. To determine the importance of cell geometry in division plane orientation, we designed a three-dimensional probabilistic mathematical model to directly test the century-old hypothesis that cell divisions mimic soap-film minima. According to this hypothesis, daughter cells have equal volume and the division plane occurs where the surface area is at a minimum. We compared predicted division planes to a plant microtubule array that marks the division site, the preprophase band (PPB). PPB location typically matched one of the predicted divisions. Predicted divisions offset from the PPB occurred when a neighboring cell wall or PPB was directly adjacent to the predicted division site to avoid creating a potentially structurally unfavorable four-way junction. By comparing divisions of differently shaped plant cells (maize [Zea mays] epidermal cells and developing ligule cells and Arabidopsis thaliana guard cells) and animal cells (Caenorhabditis elegans embryonic cells) to divisions simulated in silico, we demonstrate the generality of this model to accurately predict in vivo division. This powerful model can be used to separate the contribution of geometry from mechanical stresses or developmental regulation in predicting division plane orientation.

Singling Out Chromosome Gains in Tumor Evolution

In this issue of Cancer Cell, Sheltzer etal. shed new light on Theodor Boveri's century-old hypothesis by demonstrating that aneuploidy characterized by single-chromosome gains acts to suppress tumorigenesis and that aneuploidy itself is a nidus for genomic instability.

Holocene subsidence at the transition between strike-slip and subduction on the Pacific-Australian plate boundary, Marlborough Sounds, New Zealand

This paper provides the first solid evidence in support of a century-old hypothesis that the mountainous Marlborough Sounds region in central New Zealand is subsiding. More recent hypotheses suggest that this may be a result of southward migration of a slab of subducted Pacific Plate causing flexural downwarping of the overlying crust in the vicinity of the transition between subduction and strike-slip on the Pacific-Australian plate boundary. The proxy evidence for gradual Holocene subsidence comes from micropaleontological study of seven intertidal sediment cores from the inner Marlborough Sounds (at Havelock, Mahau Sound and Shakespeare Bay). Quantitative estimates (using Modern Analogue Technique) of former tidal elevations based on fossil foraminiferal faunas provide evidence of tectonic (not compaction-related) subsidence in all cores. Estimates of subsidence rates for individual cores vary within the range 0.2–2.4 m ka −1. The wide variation within subsidence rate estimates are related to a combination of the accuracy limits of radiocarbon dates, elevation estimates, and particularly our poor knowledge of the New Zealand Holocene sea-level curve. The most consistent subsidence rate at all three sites for the mid-late Holocene (last 6–7 ka) is ∼0.7–0.8 m ka −1. This rate is consistent with the average subsidence rate in the adjacent 4-km thick Wanganui sedimentary basin for the last 5 myr. Subsidence is inferred to have migrated southwards from the Wanganui Basin to impinge on the inner Marlborough Sounds in just the last 100–200 ka.

Cell Fusion as a Hidden Force in Tumor Progression

Cell fusion plays an essential role in fertilization, formation of placenta, bone and muscle tissues, immune response, tissue repair, and regeneration. Increasing recognition of cell fusion in somatic cell dynamics has revitalized the century-old hypothesis that cell fusion may contribute to the initiation and progression of cancer. In this review, we discuss findings from experimental and clinical studies that suggest a potentially multifaceted involvement of cell fusion in different stages of tumor progression, including aneuploidy and tumor initiation, origin of cancer stem cells, multidrug resistance, and the acquisition and diversification of metastatic abilities.

Shakespeare's Edward III : A Consolation for English Recusants

Shakespeare's EdwardIII: A Consolation for English Recusants J. P. CONLAN With the publication of three new editions in the past five years, The Raign ofKing Edward the Third has reemerged as a prominent candidate for inclusion in the Shakespeare canon.1 Nonetheless, the play still continues to be received with suspicion. Critics recognize it is written in a genre, the chronicle history, that Shakespeare dominated in his day and admit the play has the same variety of imagery, a similar texture ofvocabulary, and verbal parallels to Shakespeare's other dramas.2 Notwithstanding, few scholars are willing to embrace the play wholeheartedly as Shakespeare's own. The problem, they claim, is the play lacks dramatic unity. As they see it, the play appears to be divided into two poorly integrated halves. The first two acts focus on the king's campaign to seduce the Countess of Salisbury; then, the theater of operations shifts abruptly to France and the Hundred Years' War to detail the English conquests at Sluys, Crecy, Calais, and Poitiers. This largely unexplained bifurcation within the play between love and war, shame and honor, England and France, has cast the play and its playwright into disrepute for centuries, and it is upon this legacy ofcensure that skepticism about Shakespeare's authorship of the play has its most secure foundation.3 Among those who see Shakespeare's hand in the play, this perceived lack ofdramatic unity has generated a wide range ofspecial pleading. To explain this singular fact, A. F. Hopkinson has told us that Shakespeare's "sublimegeniusspurnedatarbitraryrulesandrestraints,"4thatthetwoplots in themselves must be considered as separate plays, and as the dramatic unity in each is perfect, the play as a whole is therefore in Shakespeare's manner.5 Kenneth Muir has told us that Shakespeare collaborated with 177 178Comparative Drama anotherplaywright, asyet undiscovered.6Melchiori and others havetold us that Shakespeare contributed the king and countess scenes to a play alreadywritten.7 J. J. M. Tobin has told us that EdwardIIIstages an education of princes, its two episodes tied together by a concern for selfmastery .8And Eric Sams, to support his contention that past complaints about EdwardTITs lack ofdramatic unity are overstated, has argued that "each [subplot] is adroitly aligned as a separate aspect ofone single unifyingtopic , namelythe rights and wrongs ofvows and promises,"9 in the process conflating unity oftheme with unity of plot. Such descriptions of"Shakespeare's"craftsmanship,however,leavethisplayabroken thing. In neglecting the rationale that necessitates the sequence of action, the play's defenders inadvertently confirm the century-old hypothesis that "[t]hough there may indeed exist a sort of interior connexion between the episode and the principal plot, yet it appears more than doubtful whether the linkjoining the two parts was easily, ifat all, discoverable by the play-going public ofthe age."10 In actuality, this century-oldhypothesis is unfounded. In sustaining it, critics do not merely consign this play to ignominy. Edward III is most cohesive as a brilliantly incisive critique of the official propaganda sustaining the persecution of English recusants after the Invincible Armada's defeat. Denying the unity of the play and thus Shakespeare's authorship perpetuates the myth ofShakespeare as a Tudor apologist unconcerned with the course ofthe English Reformation. Allusions to the Armada's defeat within Edward III have been used to date the play, but critics remarking on them have tended to assume that the play was originally written to exploit swelling patriotic feeling.11 But this reading ofthe play is entirely too naive. Certainly to Elizabeth, as to other members of Shakespeare's audience who were educated in medieval history and who had seen in Mary's last year on the throne the loss ofCalais, Edward'svictoryinFrance wasbut a temporaryhighpoint, a peak in the long and tumultuous Hundred Years' War. Just as educated viewers would have known that the Black Prince would break his health in later years while pursuing the claim to France, finally dying in 1376, so too they would have been aware that Edward III finally succumbed to his lust, wallowing in the shocking affair with Alice Perrers, /. P. Conlan179 misconduct which encouraged the Good Parliament to impeach the King's lack ofrestraint and introduce...

Facial expressions and the regulation of emotions.

In the two decades since contemporary psychologists produced strong evidence confirming Darwin's century-old hypothesis of the innateness and universality of certain facial expressions of emotions, research on expressive behavior has become well established in developmental, social, and personality psychology and in psychophysiology. There are also signs of increased interest in emotions in clinical psychology and the neurosciences. Despite the success of the work on emotion expression and the upward trend of interest in emotions in general, the fundamental issue of the relation between emotion expression and emotion experience or feeling state remains controversial. A new developmental model of expression-feeling relations provides a framework for reevaluating previous research and for understanding the conditions under which expressions are effective in activating and regulating feeling states. The model has implications for research, socialization practices, and psychotherapy.

Facial expressions and the regulation of emotions.

In the two decades since contemporary psychologists produced strong evidence confirming Darwin's century-old hypothesis of the innateness and universality of certain facial expressions of emotions, research on expressive behavior has become well established in developmental, social, and personality psychology and in psychophysiology. There are also signs of increased interest in emotions in clinical psychology and the neurosciences. Despite the success of the work on emotion expression and the upward trend of interest in emotions in general, the fundamental issue of the relation between emotion expression and emotion experience or feeling state remains controversial. A new developmental model of expression-feeling relations provides a framework for reevaluating previous research and for understanding the conditions under which expressions are effective in activating and regulating feeling states. The model has implications for research, socialization practices, and psychotherapy.

Leaf domatia and mites on Australasian plants: ecological and evolutionary implications

Leaf domatia, specialized chambers in the vein axils on the underside of leaves of many plant species, have remained an enigma for over a century. In this study we show a strong association between foliar domatia and mites in 37 plant species in Australasia. Overall, mites accounted for 91% of the arthropods observed in domatia. Across all species, a median of 51% of domatia were occupied and 71% of leaves showed mite evidence in domatia. The level of mite association did not depend on domatia type (pit, pouch, pocket, or tuft) or provenance (Papua New Guinea, Queensland, Victoria, or New Zealand). Mite association with domatia commonly varied between plant species, between individuals within species, and between shoots within individuals. The leaf developmental stage probably explains much of the variation in association for many of these species. The presence of a variety of life history stages of mites within domatia indicates that these structures act as shelters for development and reproduction. Furthermore, in 12 of 13 plant species examined, domatia concentrate mites in particular locations on the leaf. Mite taxa that we classify as largely predaceous (e.g. phytoseiids, stigmaeids and tydeids) or fungivorous (e.g. acarids and oribatids) were most common in domatia and dominated the association in 21 of 24 plant species in which the relative abundance of herbivorous, fungivorous and predaceous groups was quantified. We evaluate hypotheses that explain the role of leaf domatia, including non-functional hypotheses (e.g. architectural constraints), physiological function (e.g. gas exchange and water uptake), bacterial symbiosis and antagonistic and mutualistic associations with mites. Our quantitative results confirm anecdotal accounts of mite association with leaf domatia and are most consistent with Lundstroem's century-old hypothesis of plant-mite mutualism in which leaf domatia billet predaceous and fungivorous mites that prey on plant enemies. Leaf domatia are widespread among woody angiosperms and abundant in many temperate and tropical regions of Australasia. Mites, an ancient group of arthropods whose diversity and abundance parallels that of insects, are likely to be important selective agents on terrestrial plants. Our results (1) indicate that mite-domatia association represents a relationship of comparable scope to plant-ant associations mediated by specialized plant structures such as extrafloral nectaries, food bodies and specialized domatia; (2) suggest that sociality is not a necessary prerequisite for widespread and diverse mutualisms between arthropods and plants; and, (3) extend the diversity of organisms that produce specialized mite ‘houses’ from lizards, and wasps and bees to woody angiosperms.

Orally transmitted Brugia pahangi in jirds ( Meriones unguiculatus)

Each of 15 anaesthetized jirds ( Meriones unguiculatus) became infected after oral instillation of 100 infective larvae of Brugia pahangi dissected from Aedes aegypti. 10 of these animals developed peripheral microfilaraemia, 3 of the remaining 5 had microfilariae in their heart-blood at necropsy, and all 15 harboured adult worms. Orally induced infections were generally comparable to conventional subcutaneous infections. In the former, however, over 90% of adult worms localized in the heart-lungs whereas in the latter many of the worms were found elsewhere in addition to the heart-lungs. With rare exceptions, worms failed to mature when infective larvae were instilled directly into the stomachs of jirds or when heavily infected mosquitoes were eaten by jirds. These observations and other evidence suggest that the stomach is not along the path taken by those larvae that succeed in establishing themselves when introduced by mouth. This appears to be the first account of oral transmission involving any filarial parasite nominally transmitted by a haematophagous arthropod. Our findings lend support to Manson's century-old hypothesis concerning oral transmission of Wuchereria bancrofti, and suggest the possibility that cryptic infection by mouth may represent a component of the epidemiology of filariasis and tropical pulmonary eosinophilia.