bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative steps in the evolution of metabolic organisation as specified by the Dynamic Energy Budget theory
Authors: Kooijman S. A. L. M. , Troost T. A. 
Published: September 2007

AbstractThe Dynamic Energy Budget (DEB) theory quantifies the metabolic organisation of organisms on the basis of mechanistically inspired assumptions. We here sketch a scenario for how its various modules, such as maintenance, storage dynamics, development, differentiation and life stages could have evolved since the beginning of life. We argue that the combination of homeostasis and maintenance induced the development of reserves and that subsequent increases in the maintenance costs came with increases of the reserve capacity. Life evolved from a multiple reserves ‐ single structure system (prokaryotes, many protoctists) to systems with multiple reserves and two structures (plants) or single reserve and single structure (animals). This had profound consequences for the possible effects of temperature on rates. We present an alternative explanation for what became known as the down‐regulation of maintenance at high growth rates in microorganisms; the density of the limiting reserve increases with the growth rate, and reserves do not require maintenance while structure‐specific maintenance costs are independent of the growth rate. This is also the mechanism behind the variation of the respiration rate with body size among species. The DEB theory specifies reserve dynamics on the basis of the requirements of weak homeostasis and partitionability. We here present a new and simple mechanism for this dynamics which accounts for the rejection of mobilised reserve by busy maintenance/growth machinery. This module, like quite a few other modules of DEB theory, uses the theory of Synthesising Units; we review recent progress in this field. The plasticity of membranes that evolved in early eukaryotes is a major step forward in metabolic evolution; we discuss quantitative aspects of the efficiency of phagocytosis relative to the excretion of digestive enzymes to illustrate its importance. Some processes of adaptation and gene expression can be understood in terms of allocation linked to the relative workload of metabolic modules in (unicellular) prokaryotes and organs in (multicellular) eukaryotes. We argue that the evolution of demand systems can only be understood in the light of that of supply systems. We illustrate some important points with data from the literature.
Parasite recruitment and oceanographic regime: evidence suggesting a relationship on a global scale
Authors: Pascual Santiago , González Ángel F. , Guerra Ángel 
Published: September 2007

AbstractWe here investigate the relationship between oceanographic processes and variability in parasite recruitment to host populations using existing data from host‐parasite systems encountering differing hydrographic conditions. Combined epidemiological data obtained from both exploited fish and cephalopod populations indicate that variability in recruitment of parasite infracommunities tends to be associated with major current systems of the World’s oceans. It appears that instability in water masses caused by physical perturbations (e.g. water mass convergence and turbulent mixing in upwelling systems) is associated with instability of trophic interactions over time, which in turn leads to a paucity of parasite communities in that area. The likely relationship between parasite recruitment and oceanographic regime should be extremely useful to the fishing industry and also as an indicator of ecosystem health.
The role of chemical communication in mate choice
Authors: Johansson Björn G. , Jones Therésa M. 
Published: September 2007

AbstractChemical signals are omnipresent in sexual communication in the vast majority of living organisms. The traditional paradigm was that their main purpose in sexual behaviour was to coordinate mate and species recognition and thus pheromones were conserved in structure and function. In recent years, this view has been challenged by theoretical analyses on the evolution of pheromones and empirical reports of mate choice based on chemical signals. The ability to measure precisely the quantity and quality of chemicals emitted by single individuals has also revealed considerable individual variation in chemical composition and release rates, and there is mounting evidence that prospecting mates respond to this variation. Here, we review the evidence for pheromones as indicators of mate quality and examine the extent of their use in individual mate assessment. We begin by briefly defining the levels of mate choice – species recognition, mate recognition and mate assessment. We then explore the degree to which pheromones satisfy the key criteria necessary for their evolution and maintenance as cues in mate assessment; that is, they should exhibit variation across individuals within a sex and species; they should honestly reflect an individual’s quality and thus be costly to produce and/or maintain; they should display relatively high levels of heritability. There is now substantial empirical evidence that pheromones can satisfy all these criteria and, while measurements of the actual metabolic cost of pheromone production remain to some degree lacking, trade‐offs between pheromone production and various fitness‐related characters such as growth rate, immunocompetence and longevity have been reported for a range of species. In the penultimate section, we outline the growing number of studies where the consequences of chemical‐based mate assessment have been investigated, specifically focussing on the reported direct and genetic benefits accrued by the receiver. Finally, we highlight potential areas for future research and in particular emphasise the need for interdisciplinary research that combines exploration of chemical, physiological and behavioural processes to further our understanding of the role of chemical cues in mate assessment.
Integrating animal temperament within ecology and evolution
Authors: Réale Denis , Reader Simon M. , Sol Daniel , McDougall Peter T. , Dingemanse Niels J. 
Published: September 2007

AbstractTemperament describes the idea that individual behavioural differences are repeatable over time and across situations. This common phenomenon covers numerous traits, such as aggressiveness, avoidance of novelty, willingness to take risks, exploration, and sociality. The study of temperament is central to animal psychology, behavioural genetics, pharmacology, and animal husbandry, but relatively few studies have examined the ecology and evolution of temperament traits. This situation is surprising, given that temperament is likely to exert an important influence on many aspects of animal ecology and evolution, and that individual variation in temperament appears to be pervasive amongst animal species. Possible explanations for this neglect of temperament include a perceived irrelevance, an insufficient understanding of the link between temperament traits and fitness, and a lack of coherence in terminology with similar traits often given different names, or different traits given the same name. We propose that temperament can and should be studied within an evolutionary ecology framework and provide a terminology that could be used as a working tool for ecological studies of temperament. Our terminology includes five major temperament trait categories: shyness‐boldness, exploration‐avoidance, activity, sociability and aggressiveness. This terminology does not make inferences regarding underlying dispositions or psychological processes, which may have restrained ecologists and evolutionary biologists from working on these traits. We present extensive literature reviews that demonstrate that temperament traits are heritable, and linked to fitness and to several other traits of importance to ecology and evolution. Furthermore, we describe ecologically relevant measurement methods and point to several ecological and evolutionary topics that would benefit from considering temperament, such as phenotypic plasticity, conservation biology, population sampling, and invasion biology.
Paternal kin discrimination: the evidence and likely mechanisms
Authors: Widdig Anja 
Published: September 2007

AbstractOne of the most important assumptions of kin selection theory is that individuals behave differently towards kin than non‐kin. In mammals, there is strong evidence that maternal kin are distinguished from non‐kinviafamiliarity. However, little is known about whether or not mammals can also recognize paternal kin as many female mammals, including primates, mate with multiple males near the time of conception, potentially concealing paternal kinship. Genetic data in several mammalian species with a promiscuous mating system and male‐biased dispersal reveal a high skew in male reproduction which leads to co‐residing paternal half‐siblings. In most primates, individuals also form stable bisexual groups creating opportunities for males to interact with their offspring. Here I consider close paternal kin co‐resident in the same social group, such as father‐offspring and paternal half‐siblings (i.e. animals sharing the same father but who were born to different mothers) and review mammalian studies of paternal kin discrimination. Furthermore, I summarize the most likely mechanisms of paternal kin discrimination (familiarity and phenotype matching). When familiarity is the underlying mechanism, mothers and/or the sire could mediate familiarity among paternal half‐siblings as well as between fathers and offspring assuming mothers and/or fathers can assess paternity. When animals use phenotype matching, they might use their fathers’ template (when the father is present) or self (when the father is absent) to assess paternal kinship in others. Available evidence suggests that familiarity and phenotype matching might be used for paternal kin discrimination and that both mechanisms might apply to a wide range of social mammals characterized by a high skew in male reproduction and co‐residence of paternal kin. Among primates, suggested evidence for phenotype matching can often have an alternative explanation, which emphasizes the crucial importance of controlling for familiarity as a potential confounding variable. However, the mechanism/s used to identify paternal kin might differ within a species (as a function of each individual’s specific circumstances) as well as among species (depending upon the key sensory modalities of the species considered). Finally, I discuss the possible cues used in paternal kin discrimination and offer suggestions for future studies.
Petroleum hydrocarbon contamination in boreal forest soils: a mycorrhizal ecosystems perspective
Authors: Robertson Susan J. , McGill William B. , Massicotte Hugues B. , Rutherford P. Michael 
Published: September 2007

AbstractThe importance of developing multi‐disciplinary approaches to solving problems relating to anthropogenic pollution is now clearly appreciated by the scientific community, and this is especially evident in boreal ecosystems exposed to escalating threats of petroleum hydrocarbon (PHC) contamination through expanded natural resource extraction activities. This review aims to synthesize information regarding the fate and behaviour of PHCs in boreal forest soils in both ecological and sustainable management contexts. From this, we hope to evaluate potential management strategies, identify gaps in knowledge and guide future research. Our central premise is that mycorrhizal systems, the ubiquitous root symbiotic fungi and associated food‐web communities, occupy the structural and functional interface between decomposition and primary production in northern forest ecosystems (i.e. underpin survival and productivity of the ecosystem as a whole), and, as such, are an appropriate focal point for such a synthesis. We provide pertinent basic information about mycorrhizas, followed by insights into the ecology of ecto‐ and ericoid mycorrhizal systems. Next, we review the fate and behaviour of PHCs in forest soils, with an emphasis on interactions with mycorrhizal fungi and associated bacteria. Finally, we summarize implications for ecosystem management. Although we have gained tremendous insights into understanding linkages between ecosystem functions and the various aspects of mycorrhizal diversity, very little is known regarding rhizosphere communities in PHC‐contaminated soils. This makes it difficult to translate ecological knowledge into environmental management strategies. Further research is required to determine which fungal symbionts are likely to survive and compete in various ecosystems, whether certain fungal ‐ plant associations gain in ecological importance following contamination events, and how PHC contamination may interfere with processes of nutrient acquisition and exchange and metabolic processes. Research is also needed to assess whether the metabolic capacity for intrinsic decomposition exists in these ecosystems, taking into account ecological variables such as presence of other organisms (and their involvement in syntrophic biodegradation), bioavailability and toxicity of mixtures of PHCs, and physical changes to the soil environment.
Ecological correlates of body size in relation to cell size and cell number: patterns in flies, fish, fruits and foliage
Authors: Arendt Jeff 
Published: September 2007

AbstractBody size is important to most aspects of biology and is also one of the most labile traits. Despite its importance we know remarkably little about the proximate (developmental) factors that determine body size under different circumstances. Here, I review what is known about how cell size and number contribute to phenetic and genetic variation in body size inDrosophila melanogaster, several fish, and fruits and leaves of some angiosperms. Variation in resources influences size primarily through changes in cell number while temperature acts through cell size. The difference in cellular mechanism may also explain the differences in growth trajectories resulting from food and temperature manipulations. There is, however, a poorly recognized interaction between food and temperature effects that needs further study. In addition, flies show a sexual dimorphism in temperature effects with the larger sex responding by changes in cell size and the smaller sex showing changes in both cell size and number. Leaf size is more variable than other organs, but there appears to be a consistent difference between how shade‐tolerant and shade‐intolerant species respond to light level. The former have larger leavesviacell size under shade, the latterviacell number in light conditions. Genetic differences, primarily from comparisons ofD. melanogaster, show similar variation. Direct selection on body size alters cell number only, while temperature selection results in increased cell size and decreased cell number. Population comparisons along latitudinal clines show that larger flies have both larger cells and more cells. Use of these proximate patterns can give clues as to how selection acts in the wild. For example, the latitudinal pattern inD. melanogasteris usually assumed to be due to temperature, but the cellular pattern does not match that seen in laboratory selection at different temperatures.
Use, misuse and extensions of “ideal gas” models of animal encounter
Authors: Hutchinson John M. C. , Waser Peter M. 
Published: September 2007

AbstractBiologists have repeatedly rediscovered classical models from physics predicting collision rates in an ideal gas. These models, and their two‐dimensional analogues, have been used to predict rates and durations of encounters among animals or social groups that move randomly and independently, given population density, velocity, and distance at which an encounter occurs. They have helped to separate cases of mixed‐species association based on behavioural attraction from those that simply reflect high population densities, and to detect cases of attraction or avoidance among conspecifics. They have been used to estimate the impact of population density, speeds of movement and size on rates of encounter between members of the opposite sex, between gametes, between predators and prey, and between observers and the individuals that they are counting. One limitation of published models has been that they predict rates of encounter, but give no means of determining whether observations differ significantly from predictions. Another uncertainty is the robustness of the predictions when animal movements deviate from the model’s assumptions in specific, biologically relevant ways. Here, we review applications of the ideal gas model, derive extensions of the model to cover some more realistic movement patterns, correct several errors that have arisen in the literature, and show how to generate confidence limits for expected rates of encounter among independently moving individuals. We illustrate these results using data from mangabey monkeys originally used along with the ideal gas model to argue that groups avoid each other. Although agent‐based simulations provide a more flexible alternative approach, the ideal gas model remains both a valuable null model and a useful, less onerous, approximation to biological reality.
On the electrodetection threshold of aquatic vertebrates with ampullary or mucous gland electroreceptor organs
Authors: Peters Rob C. , Eeuwes Lonneke B. M. , Bretschneider Franklin 
Published: September 2007

AbstractReinterpretation of research on the electric sense in aquatic organisms with ampullary organs results in the following conclusions.The detection limit of limnic vertebrates with ampullary organs is 1 μVcm−1, and of marine fish is 20 nVcm−1. Angular movements are essential for stimulation of the ampullary system in uniform d.c. fields. Angular movements in the geomagnetic field also generate induction voltages, which exceed the 20 nVcm−1 limit in marine fish. As a result, marine electrosensitive fish are sensitive to motion in the geomagnetic field, whereas limnic fish are not.Angular swimming movements generate a.c. stimuli, which act like the noise in a stochastic resonance system, and result in a detection threshold in marine organisms as low as 1 nVcm−1.Fish in the benthic space are exposed to stronger electric stimuli than fish in the pelagic space. Benthic fish scan the orientation plane for the maximum potential difference with their raster of electroreceptor organs, in order to locate bioelectric prey. This behaviour explains why the detection threshold does not depend on fish size. Pelagic marine fish are mainly exposed to electric fields caused by movements in the geomagnetic field. The straight orientation courses found in certain shark species might indicate that the electric sense functions as a simple bisensor system. Symmetrical stimulation of the sensory raster would provide an easy way to keep a straight course with respect to a far‐field stimulus. The same neural mechanism would be effective in the location of a bioelectric prey generating a near‐field stimulus.The response criteria in conditioning experiments and in experiments with spontaneous reactions are discussed.
Mammalian evolution and biomedicine: new views from phylogeny
Authors: Springer Mark S. , Murphy William J. 
Published: September 2007

AbstractRecent progress resolving the phylogenetic relationships of the major lineages of mammals has had a broad impact in evolutionary biology, comparative genomics and the biomedical sciences. Novel insights into the timing and historical biogeography of early mammalian diversification have resulted from a new molecular tree for placental mammals coupled with dating approaches that relax the assumption of the molecular clock. We highlight the numerous applications to come from a well‐resolved phylogeny and genomic prospecting in multiple lineages of mammals, from identifying regulatory elements in mammalian genomes to assessing the functional consequences of mutations in human disease loci and those driving adaptive evolution.
Ecology of Australia: the effects of nutrient‐poor soils and intense fires
Authors: Orians Gordon H. , Milewski Antoni V. 
Published: September 2007

AbstractAustralia, the flattest, driest, and geologically oldest vegetated continent, has a uniquely high proportion of nutrient‐poor soils. We develop a “Nutrient‐Poverty/Intense‐Fire Theory,” which postulates that most anomalous features of organisms and ecosystems of Australia are the evolutionary consequences of adaptations to nutrient poverty, compounded by intense fire that tends to occur as a result of nutrient poverty. The fundamental tenet of the theory is that plants growing in environments with plentiful light and periodic adequate moisture, but on soils poor in phosphorus, zinc, and other indispensible nutrients, can synthesize carbohydrates in excess of the amount that can be combined with, or catalyzed by, these nutrients for metabolism and production of nutrient‐rich foliage and reproductive tissues. They use this “expendable energy” to produce well‐defended foliage, large quantities of lignified tissues, and readily digestible exudates. Rapid accumulation of nutrient‐poor biomass, a result of low rates of herbivory, provides fuel for intense fire. Intense fire exacerbates nutrient poverty by volatilizing certain micronutrients critical for animals. Anomalous features of organisms of Australia that can be explained by this theory, rather than by climate or phylogenetic history alone, include the following: most woody plants have long‐lived, durable foliage; plants defend their tissues primarily with carbon‐rich but nutrient‐poor compounds; an unusually high proportion of plants protects seeds from fire and granivores in sturdy, woody capsules or follicles; plants allocate unusually large amounts of expendable energy to production of carbon‐based exudates, such as nectar and gums; an unusually high proportion of plant species is pollinated by vertebrates that average larger size than pollinators on other continents; herbivores are small and have slow metabolism; there are no ruminants, mammals that eat mainly subterranean plant matter, or fungus‐culturing termites and ants; vegetation dominated by leaf‐spinescent plants is more extensive than vegetation dominated by stem‐spinescent plants; nitrogen‐fixing plants are major components of most vegetation types; there is a higher proportion of myrmecochorous plant species than on any other continent; there are hardly any stem‐succulent and few leaf‐succulent, perennial, non‐halophytic plant species; and an unusually high proportion of bird species breeds cooperatively. Although the Nutrient‐Poverty/Intense‐Fire Theory can provide plausible explanations for these anomalous features, some puzzles remain, among them the great success of introduced herbivores, the lack of grazers on extensive grasslands on cracking clays, the apparently low productivity of ants, and the prominence of the parasitic plants of Australia. By examining the ratios of available energy to nutrients, particularly scarce nutrients, ecologists may identify processes not previously recognized as important for life forms or biotic adaptation on other continents.