Classical and dynamic morphology: toward a synthesis through the space of forms

In plant morphology, most structures of vascular plants can easily be assigned to pre-established organ categories. However, there are also intermediate structures that do not fit those categories associated with a classical approach to morphology. To integrate the diversity of forms in the same general framework, we constructed a theoretical morphospace based on a variety of modalities where it is possible to calculate the morphological distance between plant organs. This paper gives emphasis on shoot, leaf, leaflet and trichomes while ignoring the root. This will allow us to test the hypothesis that classical morphology (typology) and dynamic morphology occupy the same theoretical morphospace and the relationship between the two approaches remains a question of weighting of criteria. Our approach considers the shoot (i.e. leafy stem) as the basic morphological structural unit. A theoretical data table consisting of as many lines as there are possible combinations between different modalities of characters of a typical shoot was generated. By applying a principal components analysis (PCA) to these data it is possible to define a theoretical morphospace of shoots. Typical morphological elements (shoots, leaves, trichomes) and atypical structures (phylloclades, cladodes) including particular cases representing ‘exotic’ structures such as the epiphyllous appendages of Begonia and ‘water shoot’ and ‘leaf’ of aquatic Utricularia were placed in the morphospace. The more an organ differs from a typical shoot, the further away it will be from the barycentre of shoots. By giving a higher weight to variables used in classical typology, the different organ categories appear to be separate, as expected. If we do not make any particular arbitrary choice in terms of character weighting, as it is the case in the context of dynamic morphology, the clear separation between organs is replaced by a continuum. Contrary to typical structures, “intermediate” structures are only compatible with a dynamic morphology approach whether they are placed in the morphospace based on a ponderation compatible with typology or dynamic morphology. The difference in points of view between typology and continuum leads to a particular mode of weighting. By using an equal weighting of characters, contradictions due to the ponderation of characters are avoided, and the morphological concepts of continuum’ and ‘typology’ appear as sub-classes of ‘process’ or ‘dynamic morphology’.     

Categorization of environmental sounds

Sounds in the natural environment are non-stationary, in that their spectral dynamics is time-dependent. We develop measures to analyze the spectral dynamics of environmental sound signals and find that they fall into two categories—simple sounds with slowly varying spectral dynamics and complex sounds with rapidly varying spectral dynamics. Based on our results and those from auditory processing we suggest rate of spectral dynamics as a possible scheme to categorize sound signals in the environment.     

THE SETTLEMENT OF POST LARVAL MYTILUS EDULIS (SETTLEMENT OF POST LARVAL MUSSELS)

It is probable that post larval mussels cut their byssus moorings.For those that gain their freedom in this way, two modes ofpassive flotation are possible. In the ‘summer’mode, they are lifted into the water column on the end of amucus filament; in the ‘winter’ mode, they attachthemselves to certain negatively buoyant debris which leavesthe bottom when the tide flows. Passive flotation prolongs the errant existence of post larvalmussels by increasing their drag. By enabling them to avoidsilt and keep in touch with hard substrates, passive flotationmakes it more likely that they will settle advantageously. The two modes of passive flotation pose an all-the-year-roundthreat of fouling to the cooling water systems of coastal powerstations. (Received 27 April 1982;     

Patterns of correlated character evolution in flightless birds: a phylogenetic approach

Given a robust phylogeny for a particular higher taxon, it is possible to map the evolution of various character changes onto the phylogeny and study the extent to which they co-occur. Of particular interest are the questions of (a) whether particular morphological changes tend to accompany changes in ecology or behaviour to which they bear a functional relationship and (b) whether changes in those ‘primary’ morphological characters tend to be associated with correlated changes in other aspects of morphology, as would be expected given the high level of morphological integration that characterizes most organisms. Here we report a study of this kind, looking at morphological correlates of the evolution of flightlessness in birds, and using the concentrated changes test to determine whether associations are significant. We find that pectoral reduction, pelvic enlargement and changes in skull morphology significantly co-occur, and that these are usually achieved through heterochrony rather than other kinds of developmental reprogramming. This revised version was published online in November 2006 with corrections to the Cover Date.     

The contributions of mycorrhizal fungi to the determination of plant community structure

While it is now widely accepted, even by ecologists, that most plants in the majority of ecosystems are infected by mycorrhizal fungi, few experiments have been designed to investigate the function of the mutualism at the community level. Those involved with mycorrhizal research have been largely preoccupied with questions of the mineral, particularly phosphorus, nutrition of individual plants, while plant community ecologists have too often found it convenient, even when acknowledging the presence of infection, to ignore its possible function in the ecosystem. This presentation examines a selected number of seminal papers written by plant community ecologists and highlights some of ‘the most striking mysteries’ which they reveal. It describes experiments designed to determine whether knowledge of the presence and activity of the mycorrhizal mycelium can help us to unravel the ‘mysteries’ which they define. It is revealed that by having direct adverse effects upon seedlings of many ‘r’ selected species, while at the same time being beneficial, if not essential, to those that are ‘K’ selected, the activities of the mycelium of VA fungi have a direct bearing upon community composition. The extent to which ‘turf compatibility’ is actually a reflection of the compatibility of plant species with the VA mycorrhizal mycelium is discussed and the possible role of the mycelium in consigning some species to the ruderal habit is considered. It is concluded that those attempting scientifically to understand, or managerially to manipulate, plant communities, without recognizing the role of the mycorrhizal mycelium, do so at their peril, and it is recommended that scientists involved in research on mycorrhiza extend their vision beyond the limited horizons which are currently so often defined by considerations of the phosphorus nutrition of individual host plants.     

Apprehension and Pedagogy in Evolution Education

Instructors’ apprehensions and the decisions instructors make about pedagogy are often linked when it comes to teaching evolution. Whether it is the reticence of K-12 teachers that their instruction may affect their students’ religious beliefs detrimentally or that they may become caught up in some administrative, media, parental, or school political turmoil or whether it is the apprehension of college students who perceive that their religious beliefs are being explicitly challenged, such fears can be reduced by understanding their roots and by honing pedagogy in ways that reduce perceived threats. This article describes why it is prudent to address these often secretly held apprehensions and how to help instructors feel free to employ their best pedagogical methods to teach evolution without lingering fear. Some suggestions are given for pre-college and college instructors interested in combining effective pedagogy with as little perceived threat as possible. Methods are offered that allow instructors to focus on underlying scientific misconceptions even if those misconceptions are ultimately facilitated by non-scientific sources, while giving creationist or creationist-leaning students a chance to learn the appropriate scientific conceptions without their religious beliefs being explicitly threatened in a science course.     

The Linnaean system and its 250-year persistence

The Linnaean system of nomenclature has been used and adapted by biologists over a period of almost 250 years. Under the current system of codes, it is now applied to more than 2 million species of organisms. Inherent in the Linnaean system is the indication of hierarchical relationships. The Linnaean system has been justified primarily on the basis of stability. Stability can be assessed on at least two grounds: the absolute stability of names, irrespective of taxonomic concept; and the stability of names under changing concepts. Recent arguments have invoked conformity to phylogenetic methods as the primary basis for choice of nomenclatural systems, but even here stability of names as they relate to monophyletic groups is stated as the ultimate objective. The idea of absolute stability as the primary justification for nomenclatural methods was wrong from the start. The reasons are several. First, taxa are concepts, no matter the frequency of assertions to the contrary; as such, they are subject to change at all levels and always will be, with the consequence that to some degree the names we use to refer to them will also be subject to change. Second, even if the true nature of all taxa could be agreed upon, the goal would require that we discover them all and correctly recognize them for what they are. Much of biology is far from that goal at the species level and even further for supraspecific taxa. Nomenclature serves as a tool for biology. Absolute stability of taxonomic concepts—and nomenclature—would hinder scientific progress rather than promote it. It can been demonstrated that the scientific goals of systematists are far from achieved. Thus, the goal of absolute nomenclatural stability is illusory and misguided. The primary strength of the Linnaean system is its ability to portray hierarchical relationships; stability is secondary. No single system of nomenclature can ever possess all desirable attributes: i.e., convey information on hierarchical relationships, provide absolute stability in the names portraying those relationships, and provide simplicity and continuity in communicating the identities of the taxa and their relationships. Aside from myriad practical problems involved in its implementation, it must be concluded that “phylogenetic nomenclature” would not provide a more stable and effective system for communicating information on biological classifications than does the Linnaean system.     

The Function of Urease in Citrullus Seeds

Urease is present in considerable quantity in the cotyledonsof Citrullus, though elsewhere in the plant it is present onlyin traces or is absent; urease activity in the cotyledons changesduring growth, showing an initial rise followed by an abruptdrop almost to zero. These changes, under a wide variety ofconditions, are not correlated with those in the major nitrogenfractions; they are, however, closely correlated with cell extensionand the associated changes in water content and respiration.A connexion with chlorophyll formation is possible but unlikely.It is suggested that the changes in cotyledonary urease constitutemerely one aspect of the ‘protoplasmic differentiation’that takes place as a cell matures.     

Further studies on the shape of the tracking curve of an automobile and its dependence on biological parameters of the driver

Following previous studies, differential equations are established which determine the variation of the stimulus towards a corrective turn of the steering wheel and its effect on the excitation of the centers in the brain which results in the production of the corrective turn. The equations are derived under the highly oversimplified assumption that all excitation thresholds are so small that they can be neglected. Under these assumptions it is found that the tracking curve of a car is a sinusoid with negative damping, that is, with an ever increasing amplitude. Driving under these assumptions is imposible since the car will always eventually jump off the road. The possible effects of the threshold as well as stimuli towards corrective turns other than the distance from the edge of the lane are very briefly discussed. In spite of the negative results of the paper, its interest lies in the circumstance that with the complication of the model, we find that driving depends not only on the reaction times as the only “purely biological” parameter, but on three other neurobiophysical constants. In a subsequent paper (Rashevsky, 1967) it is shown how the introduction of one or more purely biological parameters of the driver makes a stable driving regime possible.     

Does proactive biodiversity conservation save costs?

Ecologists usually argue for a proactive approach to species conservation—it should start before a species is endangered and under substantial risk of extinction. In reality, however, conservation often only starts when species populations are already in a critical state. This may be the result of a policy process in which those actors who see only little or no benefits from conserving species try to delay conservation as long as possible to avoid its cost. A frequent consequence is that populations decline to critical levels so that once conservation policies set in due to legal obligations, political pressure or any other reason, additional conservation measures are required to re-establish the populations. We show that the costs associated with this policy process may be higher than those of a proactive policy. This is somewhat surprising because the costs of maintaining populations at a level at which they are not endangered may occur over a longer period. However, the costs of bringing species populations back to those levels may be so high that they outweigh the costs of the proactive approach. We develop simple cost functions that capture the main economic and ecological parameters relevant to our argument and apply them for an assessment of the costs of common hamster (Cricetus cricetus) conservation in the region of Mannheim, Germany. We find that a proactive approach would have saved between €17.2 and €36.4 mn compared to the existing policy where conservation was delayed until legal requirements forced local policy makers to implement a comprehensive hamster protection programme.     

α/β-Peptide foldamers: state of the art

Interplay between proteins, nucleic acids, carbohydrates and/or lipids is involved in almost every process in life on earth. As a consequence, a wide range of diseases results from abnormal interactions of such biomolecules. The main motivation of foldamer science is the development of scaffolds that are capable of adopting defined structures, mimicking parts of biological protagonists in their function. Among the most fundamental interactions in living beings are those between proteins, the so called protein–protein interactions (PPIs). Therefore, peptidic foldamers bear the promise to be an important tool for the inhibition of PPIs, as they are structurally most similar to the original proteins. The great number of possible permutations given by the combination of proteinogenic α-amino acid residues along with β-amino acids opens the door for a larger pool of accessible structures with potential applications. Despite the increasing amount of new secondary structure motifs, only few examples for tertiary and quaternary structure design, as well as inhibition of PPIs, have been realized so far. In this review, we summarize the current knowledge and recent progress made in the field of α/β-peptide foldamers beginning from secondary structure design up to highly sophisticated biological applications, such as protein surface recognition and inhibition of HIV cell entry.     

What Stakeholders Think About Marine Protected Areas: Case Studies from Spain

Marine protected areas (MPAs) are often met with reluctance by affected stakeholders, and in some instances outright objection. Some argue that this is due to insufficient understanding of the functions of MPAs. Others suggest that it could be because of a perception that they are losing more than they are gaining. It is also possible that stakeholders are generally supportive of the idea but think that the MPA should be located elsewhere. We argue that it is images people have about what the MPA is and does that determine how they react. Drawing from three MPA case studies in Spain, we illustrate the importance of critical examination of stakeholders’ images and what they imply for the governance of MPAs.     

Intensity contrast as a crucial cue for butterfly landing

Papilio butterflies use a tetrachromatic color vision to discriminate a rewarding flower, approach, land and take nectar from the flower. In the course of further analyzing their foraging behavior in a laboratory condition, we found that some butterflies could not land on the target flower even they discriminated and tried to land on it, especially when the target was dark. This phenomenon, which we call “landing suppression”, indicates that the cue for landing differs from the cue for visually locating a flower. We hypothesized that a possible cue for landing was intensity contrast between the target and background, and have initiated to test this hypothesis. We tested the butterflies’ landing behavior to targets of various colors and intensities presented on background of black or various densities of gray. As a result, the landing was most strongly suppressed when the intensity contrast was close to zero irrespective of the target colors, suggesting that the butterflies used the target-background intensity contrast when landing.     

Resistance is useless?—Extensions to the game theory of kleptoparasitism

We extend the game theoretic model of kleptoparasitism introduced by Broom and Ruxton (1998, Behav. Ecol. 9, 397–403) in two ways: we allow for asymmetric contests, where the probability α of the challenger winning can take any value from 0 to 1; and we allow the handler to choose not to resist the challenge, but to immediately concede and relinquish its food to the challenger. We find, in general, three possible evolutionarily stable strategies—challenge-and-resist (Hawk), challenge-but-do-not-resist (Marauder) and do-not-challenge-but-resist (Retaliator). When α = 1/2, we find that Hawk and Marauder are the only ESS’s, in contrast to the result of the original model; we also find an overlap region, in parameter space, where two different ESS’s are possible, depending on initial conditions. For general α, we see that all three ESS are possible, depending on different values of the environmental parameters; however, as the average time of a contest over food becomes long, then the Marauder strategy becomes more and more prevalent. The model makes a potentially significant prediction about animal behaviour in the area of kleptoparasitism, that a searcher, when it meets a handler, will only decline to attack that handler when α < 1/2 i.e.when the defender is more likely to win. One possible converse of this statement, that a handler whose probability of success is greater than 1/2 should always resist a challenge, is not true.     

Mannose accommodation of <Emphasis Type="Italic">Vigna angularis</Emphasis> cells on solid agar medium involves its possible conversion to sucrose mediated by enhanced phosphomannose isomerase activity

Mannose is an unusable carbon source for many plants. In our study we compared the effects of mannose and sucrose on growth and sucrose levels in azuki bean (Vigna angularis) cells grown in liquid media and in solid media. The suspension cells grew actively in a liquid medium containing 90 mM sucrose but not in that containing 90 mM mannose, where the intracellular sucrose levels were reduced to 20% or less of those in sucrose-grown cells. These results suggested that the limited conversion of mannose to sucrose resulted in cell growth inhibition. When sucrose-grown suspension cells (1 × 10⁵) were transferred onto agar medium containing mannose, they grew little initially, but, after a month lag period, they started to form many callus colonies at a high apparent variation rate (1.3 × 10⁻³). Time-course studies for sugar and enzyme analysis revealed that the mannose-accommodated cells were capable of converting mannose to sucrose, with enhanced phosphomannose isomerase activity. The mannose-accommodated cells actively grew in liquid medium with sucrose but lost their ability to grow with mannose again, suggesting a specific trait of callus culture for mannose utilization. The possible differences in the metabolic activities and other physiological characteristics are discussed between callus and suspension cells. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Foraging strategies of incubating and brooding king penguins Aptenodytes patagonicus

For oceanic birds like king penguins, a major constraint is the separation of foraging areas from the breeding colony, largely because swimming increases foraging costs. However, the relationship between foraging strategy and breeding stage has been poorly investigated. Using time-depth recorders, we studied the diving behaviour of two groups of king penguins that were either incubating or brooding chicks at Crozet Islands (Southern Indian Ocean) at the same period of the year. Although birds with chicks had the highest predicted energy demand, they made foraging trips half as long as incubating birds (6 vs. 14 days) and modified their time and depth utilisation. Birds with chicks dived deeper during daylight (mean maximum depth of 280 m vs. 205 m for those incubating). At night, birds with chicks spent twice as much time diving as those incubating, but birds at both stages never dived beyond 30 m. Movements to greater depths by brooding birds are consistent with the vertical distribution of myctophid fish which are the main prey. As chick provisioning limits trip duration, it is suggested that it is more efficient for parents to change their diving patterns rather than to restrict their foraging range. Received: 23 June 1997 / Accepted: 3 November 1997     

Autochthonous fermentation starters for the industrial production of Negroamaro wines

The aim of the present study was to establish a new procedure for the oenological selection of Saccharomyces cerevisiae strains isolated from natural must fermentations of an important Italian grape cultivar, denoted as “Negroamaro”. For this purpose, 108 S. cerevisiae strains were selected as they did not produce H₂S and then assayed by microfermentation tests. The adopted procedure made it possible to identify 10 strains that were low producers of acetic acid and hydrogen sulphide and showed that they completed sugar consumption during fermentation. These strains were characterized for their specific oenological and technological properties and, two of them, strains 6993 and 6920, are good candidates as industrial starter cultures. A novel protocol was set up for their biomass production and they were employed for industrial-scale fermentation in two industrial cellars. The two strains successfully dominated the fermentation process and contributed to increasing the wines’ organoleptic quality. The proposed procedure could be very effective for selecting “company-specific” yeast strains, ideal for the production of typical regional wines. “Winery” starter cultures could be produced on request in a small plant just before or during the vintage season and distributed as a fresh liquid concentrate culture.     

Assortative pairing and divergent evolution in Darwin’s Small Tree Finch, Camarhynchus parvulus

Size assortative mating has received increasing attention due to its potential to drive divergence and perhaps speciation. In this study, we examined assortative pairing at 17 nests of Darwin’s Small Tree Finches, Camarhynchus parvulus. We found positive assortative pairing for two traits: bill length and tarsus length, and these traits showed a significant positive correlation to each other. Assortative pairing could be driven by female choice for similar phenotypes because male–male competition has rarely been observed in the Small Tree Finch, nor have males been observed to reject potential mates. Given the high heritability of bill morphology in Darwin’s finches, it is possible that female preference for male bill length, a trait that is known to be important for foraging, will influence offspring bill size to maximise efficient exploitation of resources. The finding of size assortative pairing on the basis of tarsus length requires more research, but suggests different trait utilities for different foraging niches. Interestingly, the highland distribution of tarsus length across the population showed a unimodal distribution, but a bimodal distribution after pairing. While not significant, we found comparatively large differences across study plots in tarsus length, which suggests the possibility of phenotype–habitat matching at a small spatial scale in this species. Our findings are significant in the context of the adaptive radiation of Darwin’s finches as they are consistent with the allopatric model of speciation but also show potential for adaptive divergence in sympatry in Darwin’s tree finches.     

A positive association between oviposition and fruit set: female choice or manipulation?

The relationship between where a female chooses to oviposit and her larvae’s performance at those sites is critical to both the ecology and evolution of plant-insect interactions. For predispersal seed predators that do not themselves pollinate their host and whose larvae are sessile, females must be able to predict which flowers will ultimately be pollinated and set fruit, or be able to manipulate flowers in some way to ensure they set fruit. Otherwise, their offspring will perish. Here we describe the results of an experiment in which we tested if female Hylemya (Diptera: Anthomyiidae) are choosing oviposition sites wisely, or if they are manipulating flowers of their host, Ipomopsis aggregata (Polemoniaceae), in some way to ensure fruit set. Previous work in this system established a positive correlation between oviposition and fruit set. By bagging females on flowers, we removed their ability to choose flowers on which to oviposit. We found that flowers females oviposited on, whether bagged (”no choice”) or unbagged (”female choice”), had a significantly higher probability of setting fruit than ”control” flowers that we bagged but did not cage females on. In addition, we tested if Hylemya prefer particular architectural locations of flowers and if those locations correspond with higher than average fruit set. Although flowers at the distal end of the plant, and those most proximal to the main stem, were more likely to set fruit overall, Hylemya was no more likely to oviposit on those flowers than others on the plant. Taken together, our results suggest that Hylemya is somehow able to manipulate its host to ensure fruit set and thus the provisioning of their larvae. Received: 3 December 1999 / Accepted: 23 March 2000