Is fatter fitter? Body storage and reproduction in ten populations of the freshwater amphipod Gammarus minus

Relationships between body storage (estimated as fat content and residuals of body mass regressed against body length) and offspring investment [brood mass, brood size (number of embryos per brood) and embryo mass] were examined within and among populations of the amphipod Gammarus minus in ten cold springs in central Pennsylvania, USA. Two major hypotheses and six corollary hypotheses were tested. Total reproductive investment (brood mass and brood size) was usually strongly positively correlated with maternal body length and body storage both within and among populations. These positive associations between reproductive and somatic investments are expected if individual variation in resource acquisition exceeds that of resource allocation. That is, individuals or populations that are able to acquire more resources should also be able to allocate more resources to both reproduction and somatic reserves than those acquiring fewer resources. This hypothesis is consistent with evidence showing that individual differences in body storage in G. minus and other amphipods are related to differences in resource acquisition. Positive associations between reproductive and somatic investments do not mean that energy costs of reproduction do not exist in G. minus. Evidence for reproductive energy costs included the lower body-fat contents of brooding versus nonbrooding females and the relatively low body mass per length of females who had just deposited eggs in their brood pouch. Unlike brood mass and brood size, individual embryo mass was usually unrelated to maternal body length and body storage. This pattern is largely consistent with optimal offspring investment theory, which predicts that offspring size should be insensitive to variation in parental resource status. However, in contrast to theory, embryo mass increased in winter when brooding females were significantly ”fatter”, presumably due to the availability of autumn-shed leaf food. This seasonal change in offspring size may be a maternally mediated effect of increased resource availability, though other explanations are possible. Overall, this study suggests that ”fatter” female amphipods are fitter than ”thinner” ones, though both the costs and benefits of increased body storage and brood size require investigation to substantiate this claim. This study also suggests that effects of individual variation in resource acquisition on life-history patterns deserve more theoretical and empirical attention by ecologists than they have received. It should be recognized that positive and/or nonsignificant correlations between life-history traits are just as interesting and important as are the negative correlations predicted by many theoretical models. Received: 20 January 1999 / Accepted: 26 September 1999     

Resource distribution influences mating system in the bobuck (<Emphasis Type="Italic">Trichosurus cunninghami</Emphasis>: Marsupialia)

Mammalian mating systems are thought to be shaped by the spatial distribution and abundance of key resources, which in turn influence the spacing behaviour of individuals. In particular, female home range size is predicted to reflect the availability of key resources. We documented the availability and distribution of food and shelter resources for two neighbouring populations of bobucks, or mountain brushtail possums, Trichosurus cunninghami, that were characterised by different mating systems: our “forest population” was socially monogamous, whereas the “roadside population” was polygynous. Both silver wattle, Acacia dealbata, the main food resource for bobucks, and den-trees, which provided shelter, occurred at significantly higher density at the roadside site. The pattern of distribution of these two resources also differed between the sites. Both food and den-trees were scattered evenly throughout the roadside habitat. In contrast, den-trees were located predominantly at one end of the forest site, while silver wattle trees were located at the other. There was no significant difference in the amount of silver wattle, or in the number of den-trees, located within the home ranges of individual females at the two sites. However, forest females had home ranges, on average, almost three times the size of those of roadside females. At the roadside site, the size of female home ranges varied inversely with the density of silver wattle, indicating that these females ranged over as large an area as necessary to gain access to sufficient silver wattle trees. There was no such relationship among forest females. These populations provide a clear example of resource distribution determining female home range size. This influenced the number of female home ranges a male’s home range overlapped with, which in turn determined the mating system. Such clear links between resource availability and mating system have not previously been established in a marsupial.     

Joseph Hooker Takes a “Fixed Post”: Transmutation and the “Present Unsatisfactory State of Systematic Botany”, 1844–1860

Joseph Hooker first learned that Charles Darwin believed in the transmutation of species in 1844. For the next 14 years, Hooker remained a “nonconsenter” to Darwin’s views, resolving to keep the question of species origin “subservient to Botany instead of Botany to it, as must be the true relation”. Hooker placed particular emphasis on the need for any theory of species origin to support the broad taxonomic delimitation of species, a highly contentious issue. His always provisional support for special creation waned during the 1850s as he lost faith in its expediency for coordinating the study of plant geography, systematics and physiology. In 1858, Hooker embraced Darwin’s “considerable revolution in natural history,” but only after Darwin had carefully molded his transmutationism to meet Hooker’s exacting specifications.     

Sibling rivalry between seeds within a fruit: Some population genetic models

Competition between seeds within a fruit for parental resources is described using one-locus-two-allele models. While a “normal” allele leads to an equitable distribution of resources between seeds (a situation which also corresponds to the parental optimum), the “selfish” allele is assumed to cause the seed carrying it to usurp a higher proportion of the resources. The outcome of competition between “selfish” alleles is also assumed to lead to an asymmetric distribution of resources, the “winner” being chosen randomly. Conditions for the spread of an initially rare selfish allele and the optimal resource allocation corresponding to the evolutionarily stable strategy, derived for species with n-seeded fruits, are in accordance with expectations based on Hamilton’s inclusive fitness criteria. Competition between seeds is seen to be most intense when there are only two seeds, and decreases with increasing number of seeds, suggesting that two-seeded fruits would be rarer than one-seeded or many-seeded ones. Available data from a large number of plant species are consistent with this prediction of the model. Based on a talk given at the Haldane Centenary Symposium held on 6 November 1992 at Ahmedabad as part of the 58th Annual Meeting of the Indian Academy of Sciences.     

J D Bernal (1901–1971) in perspective

Conclusion We must conclude that the sub-title of Bernal’s “The Social Function of Science” — “What science does: what science could do” is still the relevant challenge and indicates Bernal’s chief contribution, besides the foundation of molecular biology to our civilization. It is manifest that resources spent on armaments are a monstrous pathological symptom of our social structure. The ancient problem of “what is property” and what may be “owned” and by whom or by what organs of society is awakening.     

Living Precisely in Fin-de-Siècle Vienna

Vienna’s Institute of Experimental Biology, better known as the Vivarium, helped pioneer the quantification of experimental biology from 1903 to 1938. Among its noteable scientists were the director Hans Przibram and his brother Karl (a physicist), Paul Kammerer, Eugen Steinach, Paul Weiss, and Karl Frisch. The Vivarium’s scientists sought to derive laws describing the development of the individual organism and its relationship to the environment. Unlike other contemporary proponents of biological laws, however, these researchers created an explicitly anti-deterministic science. By “laws” they meant statistical regularities or “patterns.” They interpreted their experimental results in ways that forged a “third way” between determinism and pure spontaneity, aiming to capture the complexity of the interaction between the organism and its environment. This common feature of their research was made possible by the availability at the Vivarium of the latest in climate-control technology and of methods borrowed from statistical physics. The deeper roots of this search for a “third way” lay, I suggest, in the shared educational, social, and aesthetic experiences of the laboratory’s workers.     

Comparative parasitological examination on sympatric equids in the Great Gobi “B” Strictly Protected Area,Mongolia

The Przewalski’s horse (Equus caballus przewalskii) became extinct in the wild during the 1960s. Based on a successful captive breeding program, Przewalski’s horses were reintroduced to the Great Gobi Part “B” strictly protected area (SPA) in SW Mongolia in the late 1990s. The Asiatic wild ass (Equus hemionus hemionus), Przewalski’s horse, and sometimes domestic horses live sympatricly in the Gobi B SPA. Previously published data demonstrates that, as a result of their different requirements and utilization of the park’s resources, their home-range size and social structure differ. Parasitological examinations in the three equid species show how the factors “home range, social structure, and resource selection” significantly impact parasitic burden. Asiatic wild asses are potentially exposed to a higher risk of parasite re-infection due to their temporal aggregation in very large groups. This study demonstrates a highly significant greater parasite load in the Asiatic wild ass for the majority of parasites evaluated (Dictyocaulus arnfieldi, Trichostrongylus axei, Strongyloides westeri, Parascaris equorum) compared to Przewalski’s horses and domestic horses in the same habitat. Domestic horses had higher parasite loads for eggs of strongylids, eggs of anoplocephalidae, and Eimeria leuckarti. The potential risk of cross infection between sympatric living equids is high, as is the cross infection between ruminants and equids. Furthermore, this study reports for the first time the occurrence of lungworms in free-ranging Przewalski’s horses. Whereas, Asiatic wild asses and Przewalski’s horses seem to cope very well with the sometimes high parasite burden, Mongolian domestic horses manifested typical parasite burden symptoms.     

The roles of body size and phylogeny in fast and slow life histories

Species’ life histories are often classified on a continuum from “fast” to “slow”, yet there is no consistently used definition of this continuum. For example, some researchers include body mass as one of the traits defining the continuum, others factor it out by analysing body-mass residuals, a third group performs both of these analyses and uses the terms “fast” and “slow” in both ways, while still others do not mention body mass at all. Our analysis of European and North American freshwater fish, mammals, and birds (N = 2,288 species) shows the fundamental differences between life-history patterns of raw data and of body-mass residuals. Specifically, in fish and mammals, the number of traits defining the continuum decreases if body-mass residuals are analysed. In birds, the continuum is defined by a different set of traits if body mass is factored out. Our study also exposes important dissimilarities among the three taxonomic groups analysed. For example, while mammals and birds with a “slow” life history have a low fecundity, the opposite is true for fish. We conclude that our understanding of life histories will improve if differences between patterns of raw data and of body-mass residuals are acknowledged, as well as differences among taxonomic groups, instead of using the “fast–slow continuum” too indiscriminately for any covarying traits that appear to suit the idea.     

“Not <Emphasis Type="Italic">Here</Emphasis>”: Making the Spaces and Subjects of “Global Health” in Botswana

This essay argues that what makes “global health” “global” has more to do with configurations of space and time, and the claims to expertise and moral stances these configurations make possible, than with the geographical distribution of medical experts or the universal, if also uneven, distribution of threats to health. Drawing on a study of public–private partnerships supporting Botswana’s HIV/AIDS treatment program, this essay demonstrates ethnographically the processes by which “global health” and its quintessential spaces, namely “resource-limited” or “resource-poor settings,” are constituted, reinforced, and contested in the context of medical education and medical practice in Botswana’s largest hospital. Using Silverstein’s work on orders of indexicality, I argue that the terms of “global health” are best understood as chronotopic, and demonstrate how actors orient themselves and others spatio-temporally, morally, and professionally by using or refuting those terms. I conclude by arguing that taking “global health” on its own terms obscures the powerful forces by which it becomes intelligible. At stake are the frames within which medical anthropologists understand their objects of study, as well as the potential for the spaces of “global health” intervention to expand ever outward as American medical personnel attempt to calibrate their experiences to their expectations.     

Ontogeny, anatomy, and the problem of homology: Carl Gegenbaur and the American tradition of cell lineage studies

Summary In this paper we analyze Carl Gegenbaur’s conception of the relationship between embryology (“Ontogenie”) and comparative anatomy and his related ideas about homology. We argue that Gegenbaur’s conviction of the primacy of comparative anatomy and his careful consideration of caenogenesis led him to a more balanced view about the relationship between ontogeny and phylogeny than his good friend Ernst Haeckel. We also argue that Gegenbaur’s ideas about the centrality of comparative anatomy and his definitions of homology actually laid the conceptual foundations for Hans Spemann’s (1915) later analysis of homology. We also analyze Gegenbaur’s reception in the United States and how the discussions between E.B. Wilson and Edwin Conklin about the role of the “embryological criterion of homology” and the latter’s argument for an even earlier concept of cellular homology reflect the recurring theme of preformism in ontogeny, a theme that finds its modern equivalent in various genetic definitions of homology, only recently challenged by the emerging synthesis of evolutionary developmental biology. Finally, we conclude that Gegenbaur’s own careful methodological principles can serve as an important model for proponents of present day “evo-devo”, especially with respect to the integration of ontogeny with phylogeny embedded in comparative anatomy.     

The “Cycle of Life” in Ecology: Sergei Vinogradskii’s Soil Microbiology, 1885–1940

Historians of science have attributed the emergence of ecology as a discipline in the late nineteenth century to the synthesis of Humboldtian botanical geography and Darwinian evolution. In this essay, I begin to explore another, largely neglected but very important dimension of this history. Using Sergei Vinogradskii’s career and scientific research trajectory as a point of entry, I illustrate the manner in which microbiologists, chemists, botanists, and plant physiologists inscribed the concept of a “cycle of life” into their investigations. Their research transformed a longstanding notion into the fundamental approaches and concepts that underlay the new ecological disciplines that emerged in the 1920s. Pasteur thus joins Humboldt as a foundational figure in ecological thinking, and the broader picture that emerges of the history of ecology explains some otherwise puzzling features of that discipline – such as its fusion of experimental and natural historical methodologies. Vinogradskii’s personal “cycle of life” is also interesting as an example of the interplay between Russian and Western European scientific networks and intellectual traditions. Trained in Russia to investigate nature as a super-organism comprised of circulating energy, matter, and life; over the course of five decades – in contact with scientists and scientific discourses in France, Germany, and Switzerland – he developed a series of research methods that translated the concept of a “cycle of life” into an ecologically conceived soil science and microbiology in the 1920s and 1930s. These methods, bolstered by his authority as a founding father of microbiology, captured the attention of an international network of scientists. Vinogradskii’s conceptualization of the “cycle of life” as chemosynthesis, autotrophy, and global nutrient cycles attracted the attention of ecosystem ecologists; and his methods appealed to practitioners at agricultural experiment stations and microbiological institutes in the United States, Western Europe, and the Soviet Union.     

The occurrence and significance of amino acids in floral nectar

Approximately 1 500 angiosperm species, in previous papers, have been sampled for the assessment of the amino acids (a. a.) in their nectar. We reaffirm that the findings provide statistically significant data linking differences in the concentration with pollinator type. Flowers that are pollinated by animals that have alternative sources of protein-building a. a.’s show lower a. a. concentration than those that are not. There is a tendency for woody plant nectar a. a.’s to be less concentrated than those of herbaceous plants, but there can be “phylogenetic constraints” which may reduce the correlations of a. a. concentration with pollinator type and with life form. The individual a. a.’s form complements which are qualitatively extremely constant within species. Proline is a normal constituent of many nectars and does not necessarily indicate contamination of the nectar by pollen. Criticism of our findings byGottsberger & al. (1984) is answered by reference to our previous publications and those of other workers, and to the presentation of data from California native species, not published previously. All previous postulates are borne out by these new data with the exception of positive correlations of a. a. concentration with “primitive” and “advanced” floral characteristics taken one at a time, which appear to be inconsistent and are affected strongly by the nature of the family in which they occur. Summary data are provided for families and genera which indicate that high or low a. a. concentration can typify certain families and genera of both relatively “primitive” and relatively “advanced” nature. Needs for future research on an ecosystem basis are quoted.     

Science through the internet: Researching, evaluating and citing websites

This article attempts to convey the joys and frustrations of skimming the Internet trying to find relevant information concerning an academic’s work as a scientist, a student or an instructor. A brief overview of the Internet and the “do’s and don’ts” for the neophyte as well for the more seasoned “navigator” are given. Some guidelines of “what works and what does not” and “what is out there” are provided for the scientist with specific emphasis for biologists, as well as for all others having an interest in science but with little interest in spending countless hours “surfing the net”. An extensive but not exhaustive list of related websites is provided.     

Sluggishness of auditory perception during localization of short moving sound images

During localization of a moving sound source, a shift of the perceived position relative to the actual one of the starting point is an expression of the perception of sluggishness of the auditory system. In this study, the human ability to localize starting points during a gradual or abrupt movement of fused auditory images (FAIs) was compared with the ability to localize the position of a stationary sound image. Sound images moved from the midline of the head in the direction of each of the ears. The subject’s responses were recorded using a graphics table. There was a tendency to shift the starting point of the trajectory in the direction of the movement. This tendency was stronger for gradual rather than for abrupt FAI movement and for shorter stimuli (100 ms) than for long ones (200 ms). The value of the starting point’s displacement depended on the final interaural time delay. The results obtained are discussed in terms of the “snapshots” and “movement detector” theories, as well as in terms of the sluggish and anticipatory ability of auditory perception.     

Structure and function of a non-interactive, reactive insect-plant system

Rhagoletis alternata is a common tephritid fly in central Europe, whose larvae feed on the hypanthium of rose hips. The resource-consumer system is “non-interactive”, i.e. the insect has little or no impact on host plant fitness and therefore is not able to influence the rate at which larval food resources are renewed. The system is “reactive”, since fluctuations in the carrying capacity (hip density) of the host plant are important for determining year-to-year fluctuations in the insect's population size. Insect fluctuations exceed those of its carrying capacity. The insect's efficient exploitation strategy, maximizing its fitness at high as well as low resource supply, must be attributed to the variable and unpredictable relationship between resource availability and consumer density. The only regulatory mechanism is contest competition when larval densities exceed the carrying capacity. Due to the low impact of the insect, its exploitation strategy is apparently not opposed by mechanisms selecting for defence in the host plant. This lack of defence and the efficient exploitation strategy may be important factors for the frequently observed high degree of the resource utilization by the insect. Received: 3 November 1997 / Accepted: 22 January 1998     

Multi drug resistance-dependent “vacuum cleaner” functionality potentially driven by the interactions between endocytosis, drug size and Pgp-like transporters surface density

In cells, multi drug resistance (MDR) is associated with Pgp-like transporters expression extruding drugs from cellular membranes. MDR is efficiently generated with a relatively small fraction of membrane transporters. As the insertion of drugs into cellular membranes is widespread, there are no reasons why a drug should incorporate the membrane in the vicinity of a transporter. As a result a further elusive hypothesis is usually invoked: these transporters act like “vacuum cleaners” of drugs embedded in the membrane. Nonetheless, how these transporters attract drugs remains obscure. To clarify the “vacuum cleaner” notion, we suggest that during its residency time in cellular membranes, the lateral movement of drugs from their point of insertion to transporters is governed by Brownian’s diffusion, which allows the drugs/transporters interaction. Taking into account the functionality of Pgp-like transporters, namely the extrusion of drugs from the plasma membrane inner leaflet, we characterize how the state of drug resistance is triggered involving: membrane endocytosis, drug physico-chemical properties and the surface density of Pgp-like transporters. In addition, the theory developed provides for the first time a theoretical proof of Lipinski’s second rule with regard to drugs’ size (or MW) selectivity on their permeation across cellular membranes. Electronic Supplementary Material Supplementary material is available in the online version of this article at ) and is accessible for authorized users.     

Predicting abundance–body size relationships in functional and taxonomic subsets of food webs

Abundance–body size relationships are widely observed macroecological patterns in complete food webs and in taxonomically or functionally defined subsets of those webs. Observed abundance–body size relationships have frequently been compared with predictions based on the energetic equivalence hypothesis and, more recently, with predictions based on energy availability to different body size classes. Here, we consider the ways in which working with taxonomically or functionally defined subsets of food webs affected the relationship between the predicted and observed scaling of biomass and body mass in sediment dwelling benthic invertebrate communities at three sites in the North Sea. At each site, the energy available to body size classes in the “whole” community (community defined as all animals of 0.03125–32.0 g shell-free wet weight) and in three subsets was predicted from estimates of trophic level based on nitrogen stable isotope analysis. The observed and predicted scalings of biomass and body size were not significantly different for the whole community, and reflected an increase in energy availability with body size. However, the results for subsets showed that energy availability could increase or decrease with body size, and that individuals in the subsets were likely to be competing with individuals outside the subsets for energy. We conclude that the study of abundance–body mass relationships in functionally or taxonomically defined subsets of food webs is unlikely to provide an adequate test of the energetic equivalence hypothesis or other relationships between energy availability and scaling. To consistently and reliably interpret the results of these tests, it is necessary to know about energy availability as a function of body size both within and outside the subset considered.     

The Charms of Nature: Darwin on Meaning and Value

I review George Levine’s provocative and highly original book Darwin Loves You. Levine, whose “home discipline” is English Literature, offers a compelling interpretation of Darwin’s works, evaluating their content and Darwin’s prose style to identify a distinctly Darwinian attitude toward nature as a source of meaning and value. Levine believes that Darwin exemplifies the capacity to feel “enchantment” about the natural world, suggesting that, if Darwin’s example were followed, a “Darwinian re-enchantment of the world” would be brought about. This would offer a secular, non-supernatural basis for purpose, meaning, and value. I conclude with a few critical remarks about the scope and cogency of Levine’s proposal.     

Patterns of sexual size dimorphism in cattle breeds support Rensch’s rule

Rensch’s rule describes the pattern of sexual size dimorphism (SSD) claiming that in taxa where males are the larger sex, larger species generally exhibit higher male to female body size ratios. Agreement with Rensch’s rule is manifested by the slope of the allometric relationship between male and female body size exceeding one. In this paper we have tested the hypothesis that recent rapid evolutionary changes of body size accompanying domestication process and morphological radiation of domestic breeds follow Rensch’s rule. We have analyzed literature data on adult body size of males and females in domestic cows, yaks, buffaloes and other bovines (315, 12, 24 and 2 breeds, respectively) and compared it with SSD in 18 wild species/subspecies of the subfamily Bovinae. Male to female body mass ratio in domestic cows (1.48) was fairly comparable to that found in other species of domestic and wild bovines except domestic buffaloes (1.19). In cows we have demonstrated clear positive allometry of male to female body mass ratio (slope 1.21) predicted by Rensch’s rule, however, no such clear relationship was found when body mass was replaced by shoulder height. These findings are in agreement with those we have previously reported in other livestock species, goats and sheep.