Energetic Equivalence Research Articles

Scaling of Population Density on Body Mass and a Number-Size Trade-Off

The energetic equivalence rule (EER). that is the negative relationship between population density and body mass with the body mass exponent of -0.75, is often observed for mammal species assemblages studied at regional scales. Little, however, is known about the mechanism that may generate it. Here we attempt to explain EER in terms of demography and life-history theory, namely on the basis of an interspecific trade-off between total lifetime female offspring and relative mass at birth. Based on data on 85 species of non-flying mammals from the territory and coastal waters of the former Soviet Union, we show that the number of offspring per lifetime is approximately inversely proportional to the relative mass at birth (the exponent is not significantly different from -1). Simple mathematics shows that given some other conditions, this minus-one trade-off entails the energetic equivalence rule. Two other consequences also follow. First, as an interspecific trade-off evolves from the intraspecific trade-off of the same type, the tendency for small-bodied species to be more abundant than large ones may have its evolutionary origin in the intraspecific trade-off between offspring number and size. Second, the trade-off may solve the paradox relating to EER: how could it be that in spite of probably unequal food availability for so different species as, for example, mice and elephants their populations consume, on average, equal amounts of energy, as the rule implies? We suggest that populations of different species consume the same amount of energy per unit area per unit time because their individual members require the same amount of energy per unit mass per lifetime, the latter being a somewhat different formulation of the minus-one trade-off between lifetime offspring number and relative mass at birth.

Allometry of territory size and metabolic rate as predictors of self‐thinning in young‐of‐the‐year Atlantic salmon

1. Self‐thinning is a progressive decline in population density caused by competitively induced losses in a cohort of growing individuals and can be depicted as: log10 (density) = c − β log10 (body mass). 2. In mobile animals, two mechanisms for self‐thinning have been proposed: (i) the space hypothesis predicts that maximum population density for a given body size is the inverse of territory size, and hence, the self‐thinning slope is the negative of the slope of the allometric territory‐size relationship; (ii) the energetic equivalence hypothesis predicts that the self‐thinning slope is the negative of the slope of the allometric metabolic rate relationship, assuming a constant supply of energy for the cohort. 3. Both hypotheses were tested by monitoring body size, population density, food availability and habitat for young‐of‐the‐year Atlantic salmon (Salmo salar) in Catamaran Brook, New Brunswick. The results were consistent with the predictions of the space hypothesis. Observed densities did not exceed the maximum densities predicted and the observed self‐thinning slope of −1·16 was not significantly different from the slope of −1·12, predicted by the allometry of territory size for the population under study. 4. The observed self‐thinning slope was significantly steeper than −0·87, predicted by the allometry of metabolic rate, perhaps because of a gradual decline in food abundance over the study period. The decline in density was more rapid in very shallow sites and may have been partly caused by a seasonal change in water depth and an ontogenetic habitat shift rather than solely by competition for food or space. 5. The allometry of territory size may be a useful predictor of self‐thinning in populations of mobile animals competing for food and space.

The value of titration experiments: a reply to Moody et al. (1996)

Behavioural ecology has been remarkably successful as a discipline, in part because much of the theory that has been developed is readily testable through manipulative experiments in the laboratory and the ®eld. Although the preferred currency for most theories is ®tness, it has usually been possible to incorporate modi®cations or simplifying assumptions that allow the use of more readily observed, surrogate measures of ®tness. Admittedly this does require some compromise, but in the grand tradition of behavioural ecology this trade-o€ is easy to solve: the bene®ts outweigh the costs. Moody et al. (1996) (henceforth referred to as MHM), explored the role that risk dilution will have on the results of experiments that investigate predation risk ± foraging trade-o€s. Assuming that the probability of being killed by a predator is inversely related to the number of animals feeding at a site, they developed a model that incorporates risk dilution into ideal free distributions (IFDs) under predation risk. Due to risk dilution, their model suggests that patch choice decisions will be a€ected not only by the presence of predators and relative food availability, but also by the total number of animals. Their suggestions are very useful in advancing our theoretical understanding of this problem. However, we disagree with their critical assessment of the use of the IFDs as an experimental tool to quantify decisions involving con icting demands. In 1989, Abrahams and Dill (henceforth referred to as AD) published a paper that described an experimental technique that could be used to quantify the energetic equivalence of the risk of predation and, more importantly, presented the results of experiments that tested its validity. The approach is based upon a continuous-input IFD. With this type of IFD, when food is the only parameter that describes patch quality, the spatial distribution of the foragers will match the spatial distribution of their food. A large number of authors have demonstrated that under experimental conditions, animals closely conform to an IFD (for a review see Milinski and Parker 1991). Incorporation of an additional patch parameter (i.e. the risk of predation) should result in a change in the spatial distribution of animals that re ects the relative change in patch quality. Di€erences in individual intake rates will then provide a measure of the assessed value of this parameter from the animals' perspective, and can be determined empirically. This approach describes our ®rst experiment. Our second experiment then tested a prediction (derived from the results of the ®rst experiment) concerning how much additional food must be added to the dangerous patch in order for the foragers to consider it equivalent to the safe patch. To make this prediction, we assumed a linear relationship between energy and ®tness. This was not intended to describe the actual relationship between these two parameters, but to make it possible to interpret deviations in the spatial distribution with respect to the relationship between energy and ®tness. For example, if more animals than we predicted used the dangerous location after the addition of extra food, then we concluded that the ®tness bene®ts of the patch increased by more than the manipulated energy bene®ts. Conversely, if the addition of extra food resulted in fewer animals than predicted using the dangerous location, then we concluded that the ®tness bene®ts of the patch increased by less than the manipulated energy bene®ts. These experiments demonstrated that even with the linearity assumption, we could fairly accurately predict the amount of additional food that must be added to a dangerous patch to o€set the risk of predation. MHM were critical of this approach for three reasons: (1) our calculations did not incorporate risk dilution; (2) the relationship between ®tness and energy should have no in uence on the calculations necessary to Behav Ecol Sociobiol (1998) 44: 147±148 O Springer-Verlag 1998

Parasite Abundance, Body Size, Life Histories, and the Energetic Equivalence Rule

If common processes generate size-abundance relationships among all animals, then similar patterns should be observed across groups with different ecologies, such as parasites and free-living animals. We studied relationships among body size, life-history traits, and population intensity (density in infected hosts) among nematodes parasitizing mammals. Parasite size and intensity were negatively correlated independently of all other parasite and host factors considered and regardless of type of analyses (i.e., nonphylogenetic or phylogenetically based statistical analyses, and across or within communities). No other nematode life-history traits had independent effects on intensity. Slopes of size-intensity relationships were consistently shallow, around -0.20 on log-log scale, and thus inconsistent with the energetic equivalence rule. Within communities, slopes converged toward this global value as size range increased. A summary of published values suggests similar convergence toward a global value around -0.75 among free-living animals. Steeper slopes of size-abundance relationships among free-living animals could be related to fundamental differences in ecologies between parasites and free-living animals, although such generalizations require reexamination of size-abundance relationships among free-living animals with regard to confounding factors, in particular by use of phylogenetically based statistical methods. In any case, our analyses caution against simple generalizations about patterns of animal abundance.

Diet overlap and relative abundance of sympatric dasyurid carnivores: a hypothesis of competition

1. Diet overlap among age and sex classes of sympatric dasyurid carnivores (Marsupialia: Dasyuridae) at Cradle Mountain National Park in Tasmania, Australia, was determined to assess the likelihood of current interspecific competition, which could influence and explain the disparate population densities of the three species. 2. The carnivore guild divided into two groups based on body size and prey size, within which diet overlapped: Tasmanian devils (Sarcophilus laniarius) and male spotted‐tailed quolls (Dasyurus maculatus), which consumed larger prey species, and female spotted‐tailed quolls and eastern quolls (D. viverrinus), which consumed smaller prey species. Male spotted‐tailed quolls overlapped in diet with adult devils in winter, but not in summer. However, in summer the small number of male spotted‐tailed quolls overlapped in both body weight and diet with a large cohort of young devils. Too few data were obtained to repeat these analyses with female and young spotted‐tailed quolls and eastern quolls, but results indicated that a similar pattern of overlap may occur. 3. Spotted‐tailed quolls would experience the highest degree of dietary overlap with another species of carnivore, with all age and sex classes experiencing overlap for much of the year. Adult devils and young eastern quolls would both be free of overlap for more than half the year. 4. No indications of seasonal food limitation, when competition is most likely to occur, were found during this study, but this may occur over a longer time scale. 5 If the high degree of diet overlap experienced by spotted‐tailed quolls means higher competitive pressure, this may explain the low density of this species at Cradle Mountain. 6. These results, high levels of interference experienced by spotted‐tailed quolls, and the behavioural and numerical dominance of devils, the largest species in the guild, support Brown & Maurer’s (1986) and Cotgreave’s (1993) ideas that competitive dominance may be more important than energetic equivalence in determining relationships between body size and abundance in local assemblages of animals.

Parasite Abundance, Body Size, Life Histories, and the Energetic Equivalence Rule

If common processes generate size‐abundance relationships among all animals, then similar patterns should be observed across groups with different ecologies, such as parasites and free‐living animals. We studied relationships among body size, life‐history traits, and population intensity (density in infected hosts) among nematodes parasitizing mammals. Parasite size and intensity were negatively correlated independently of all other parasite and host factors considered and regardless of type of analyses (i.e., nonphylogenetic or phylogenetically based statistical analyses, and across or within communities). No other nematode life‐history traits had independent effects on intensity. Slopes of size‐intensity relationships were consistently shallow, around −0.20 on log‐log scale, and thus inconsistent with the energetic equivalence rule. Within communities, slopes converged toward this global value as size range increased. A summary of published values suggests similar convergence toward a global value around −0.75 among free‐living animals. Steeper slopes of size‐abundance relationships among free‐living animals could be related to fundamental differences in ecologies between parasites and free‐living animals, although such generalizations require reexamination of size‐abundance relationships among free‐living animals with regard to confounding factors, in particular by use of phylogenetically based statistical methods. In any case, our analyses caution against simple generalizations about patterns of animal abundance.

Energy balance for radiated waves and propagating vibration in a fluid-loaded beam under point excitation

Using a compensating solution method [S. Kovinskaya and I. Krasnov, Acta Acust. 82, 237 (1996)] a field of flexural waves propagating along a submerged beam under a point excitation and a radiated acoustical field are represented analytically. The method is based on the Fourier integral transform of the vibration equation and is similar to the hybrid method [J. M. Cuschieri and D. Feit, J. Acoust. Soc. Am. 95, 1998–2005 (1994)]. The main and compensating solutions are determined as a result of the inverse Fourier transform along a real wave number axis of nonuniform and uniform equations, correspondingly. A sum of the main and compensating solutions must supply the vibration radiation condition. Let the last equation determine an indefinite coefficient in the compensating solution. The energy balance equation based on the solution of the problem leads to an energetic equivalence between a decreasing vibration and radiated spherical wave and the same between a cylindrical acoustical wave and an energy difference in the excitation point and infinity for propagating flexural wave.

The energetic equivalence of cover to juvenile coho salmon (Oncorhynchus kisutch): ideal free distribution theroy applied

Cover U often thought to be an important habitat characteristic for juvenile stream salmonids. In addition to providing protection from predators, cover may be associated with reduced food availability. Thus, an individual's use of cover is likely to reflect a trade-off between the conflicting demands of growth and survival. We measured die influence of cover on foraging-site selection in groups of eight juvenile coho salmon (Oncorhynchus kisutch) by examining their distribution across two stream channel patches, one providing access to cover but little food (die patch), die other providing more food but no cover (die patch). Because fish distributions in the absence of cover conformed to an ideal free distribution (IFD) for unequal competitors (Le., die distribution of competitive abilities matched die distribution of food), we used IFD dieory to quantify die energetic equivalence of cover to die fish. In die presence of cover and a model avian predator, use of die poor patch increased relative to die predictions of die IFD model. Using tiiis observed deviation from an IFD, we calculated how much extra food must be added to die good patch to return die distribution of fish to die previously observed IFD of unequal competitors. As predicted, adding this amount of food caused die fish to return to dieir previous distribution, demonstrating that IFD dieory can be used to relate energy intake and risk of predation in a common currency. Key words: coho salmon, foraging, habitat selection, ideal free distribution dieory, Oncorhynchus kisutch, predation risk, trade-offs, unequal competitors. [Behav Ecol 8: 437-447 (1997)]

Relations between abundance, body size and species number in British birds and mammals

British birds and mammals are compared in terms of their frequency distributions of abundance and body mass and in respect of the relation between abundance and body mass. Body masses of non-flying mammals are greater than those of resident birds which are, in turn, heavier than migrants; bats are lightest. The frequency distribution of masses are close to log-Normal for each of these groups, though their variances and skews differ. Differences in mean abundances (which are log-Normally distributed) parallel those in body mass. In each group, abundance declines with body mass: the exponent of the relation is close to the value of —0.75 predicted by the ‘energetic equivalence’ rule though not significantly different from the value of — 1.0 predicted by the ‘biomass equivalence’ rule. At comparable masses, species of non-flying mammals are more abundant than resident birds, migrant birds and bats by approximately 45, 300 and 200 times, respectively. The similarity between birds and bats in this regard may be no more than coincidental but it may be related to ecological similarities related to flight. The metabolic rates of non-flying mammals may be generally lower than those of birds and bats but not sufficiently to account for their much greater abundances.

Abundance-Body Size Relationships: The Area You Census Tells You More

The interspecific relationship between abundance and body size in animals is often claimed to be strongly negative, with species abundance limited by energetic requirements. This view has been criticized for a number of reasons, but is still widely accepted. Here, we provide evidence of further fundamental difficulties with this relationship as derived from compendium studies. We suggest that there is a potential artefactual component to these relationships resulting from variation in the areas over which the densities of species of different body size are censused, and differences in the ways species use these areas. While the interspecific relationship between body size and abundance is still likely to be negative after accounting for the artefactual component, the slope of the relationship is unlikely to support energetic equivalence arguments.

Ideal free distributions under predation risk

We examine the trade-off between gathering food and avoiding predation in the context of patch use by a group of animals. Often a forager will have to choose between feeding sites that differ in both energetic gain rate and predation risk. The ideal site will have a high gain rate and low risk of predation. However, intake rate will often decrease when the patch is shared with other foragers and it may be optimal for some individuals to feed elsewhere. Within the framework of ideal free theory, we investigate the distribution of foragers that will equalise individual fitness gains. We focus on a two-patch environment with continuous inputs of food. With reference to existing experimental studies, we examine the effects of risk dilution, food input rates and an animal’s expectations of the future. We identify the effect of total animal numbers when one patch is subject to predation risk and the other is safe. Conditions under which the difference in intake rate in the two patches is constant are identified, as are conditions in which the ratio of animals in the two patches is constant. If current conditions do not alter future expectations an increase in input rates to the patches promotes increased use of the risky patch. Yet, if conditions are assumed to persist indefinitely the opposite effect is seen. When both patches are subject to predation risk, dilution of risk favours more extreme distributions, and may lead to more than one stable distribution. The results of these models are used to critically analyse previous work on the energetic equivalence of risk. This paper is intended to help guide the development of new experimental studies into the energy-risk trade-off.

Body Size, Population Density, and the Energetic Equivalence Rule

1. We critically evaluated the Energetic Equivalence Rule (EER) with regard to its underlying theoretical framework, its dependence of a particular relationship between population density and body size, and the way it is calculated. 2. We found it to be theoretically incorrect, not supported by empirical data on maximum population density and body size relationships, and that its calculation is misleading. In particular, we found a general pattern underlying the allometry of maximum population density, which stresses the correspondence between the documented linear patterns and triangular relationships between both variables. 3. Two independent data sets, one for mammals and another for intertidal invertebrates, showed that medium-size species attain higher population densities, and that population density decreases towards larger and smaller sizes. 4. A more direct calculation of population energy use for mammalian primary consumers, based on measured metabolic rates, showed that populations'energy use fluctuates widely among species and that its upper limit is not independent of body size but peaks at a body size of about 100 g, and decreases toward both smaller and larger body sizes. 5. Diet also has a strong effect on this relationship. Omnivores show a positive relationship between population energy use and body size, while this is negative for carnivores and insectivores

Population Density, Body Mass and Niche Overlap in Australian Birds

1. There is a negative relationship between body mass and ecological population density across 200 species of Australian birds, with a slope of -0.82 on logarithmic axes. This is not significantly different from the slope predicted by the energetic equivalence rule. 2. Contrary to previous studies, there is no tendency for the phylogenetic position of an individual tribe to correlate with the strength of the mass-density relationship across its species. 3. However, in line with recent theory, there is a relationship between the degree of niche overlap among species in a tribe and the abundance pattern of the species. Tribes in which the species appear to share few resources are those in which the relationship between mass and density is most strongly negative

In Harmony with the Earth Rotation: Is 1 kg Equal to 1 Year in Mammals?

In an interesting paper based on a comprehensive data set of 557 mammal species (Damuth 1993), a striking regularity was revealed: mammals with body masses about 1 kg have higher ecological population densities (within their dietary groups and habitat types) than expected for their body sizes on the grounds of the energetic equivalence rule. In other words, they control a greater part of the energy flow in local ecosystems, compared to both larger and smaller mammal species (Damuth 1993). The well-known relationship between body size and life-history traits could explain this phenomenon. If we consider the regression line of age at first reproduction (including both age at maturation and gestation time) on body mass based on the most complete data set of 547 mammal species (Wootton 1987), we find that a body mass of 1 kg corresponds exactly to 1 year (Wootton 1987: Fig. 1). Thus, life-cycles of such species seem to be best synchronized with an annual phenological cycle, which might have ecological advantages. The large deviations of many smaller species along the mass axis at the point of 1-year age, i.e., the retardation of their maturation (Wootton 1987: Fig. 1), suggests the great advantage of this age value. These species tend to reach this value though their masses are not optimal for it from the standpoint of a typical allometric relationship between age and mass in mammals. Such a deviation of smaller species may involve a disadvantage of wasting of time (increase of age at first reproduction not conditioned by body mass). However, reproduction more frequent than once a year (i.e., at two different seasons, one of which may be unfavorable for it) seems to incur a greater cost. On the side of larger masses, there is a corresponding 'notch' in the cloud of species points and increased density of the points at an age of 1 year. Although a similar rationale might apply to any integer-year age of first reproduction, for two-, three-, orhigher-year ages, the effect should be weaker since a piece of time (a fraction of year), on which the first reproduction is retarded or accelerated so to reach an integer age value, is smaller relative to the total age value at first reproduction (two, three or more years). In the cloud of species points in Fig. 1 of Wootton's work, a similar protrusion (increased deviations) on the smaller masses side, and a corresponding notch on the larger masses side can be seen in the two-year region also, but it is less pronounced, and evidently has a lesser effect on the regularity revealed in Damuth's work (and nothing similar can be discerned in the three-year region). It would be interesting to check whether the connection noted here (maximum energy flow in species with a body size that corresponds to age at first reproduction of about 1 year on a typical regression line) occurs in other groups of animals. It would help to reveal the significance of synchrony between the life cycle of an animal and the phenological cycle of its environment (a resonance-like effect?).

Weight-Density Relationships between and Within Bird Communities: Implications of Niche Space and Vegetation Structure

Previous articleNext article No AccessNotes and CommentsWeight-Density Relationships between and Within Bird Communities: Implications of Niche Space and Vegetation StructureJose Luis Telleria and Luis M. CarrascalJose Luis Telleria Search for more articles by this author and Luis M. Carrascal Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 143, Number 6Jun., 1994 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/285649 Views: 7Total views on this site Citations: 15Citations are reported from Crossref Copyright 1994 The University of ChicagoPDF download Crossref reports the following articles citing this article:Friedrich Wolfgang Keppeler, Danielle Ajala Cruz, Guilherme Dalponti, Roger Paulo Mormul The role of deterministic factors and stochasticity on the trophic interactions between birds and fish in temporary floodplain ponds, Hydrobiologia 773, no.11 (Mar 2016): 225–240.https://doi.org/10.1007/s10750-016-2705-yGemma E. White, Grant C. Hose, Culum Brown Influence of rock-pool characteristics on the distribution and abundance of inter-tidal fishes, Marine Ecology 36, no.44 (Nov 2014): 1332–1344.https://doi.org/10.1111/maec.12232Adam Bergner, Mustafa Avcı, Hasan Eryiğit, Nicklas Jansson, Mats Niklasson, Lars Westerberg, Per Milberg Influences of forest type and habitat structure on bird assemblages of oak (Quercus spp.) and pine (Pinus spp.) stands in southwestern Turkey, Forest Ecology and Management 336 (Jan 2015): 137–147.https://doi.org/10.1016/j.foreco.2014.10.025Luis M. Carrascal, Ismael Galván, Juan S. Sánchez-Oliver, José M. Rey Benayas Regional distribution patterns predict bird occurrence in Mediterranean cropland afforestations, Ecological Research 29, no.22 (Dec 2013): 203–211.https://doi.org/10.1007/s11284-013-1114-1Jan Hanspach, Joern Fischer, Jenny Stott, Karen Stagoll Conservation management of eastern Australian farmland birds in relation to landscape gradients, Journal of Applied Ecology 48, no.33 (Jan 2011): 523–531.https://doi.org/10.1111/j.1365-2664.2010.01948.xCOLLEEN L. SEYMOUR, W. R. J. DEAN The influence of changes in habitat structure on the species composition of bird assemblages in the southern Kalahari, Austral Ecology 35, no.55 (Nov 2009): 581–592.https://doi.org/10.1111/j.1442-9993.2009.02069.xMasakazu Hori, Takao Suzuki, Yaowaluk Monthum, Tippamas Srisombat, Yoshiyuki Tanaka, Masahiro Nakaoka, Hiroshi Mukai High seagrass diversity and canopy-height increase associated fish diversity and abundance, Marine Biology 156, no.77 (Mar 2009): 1447–1458.https://doi.org/10.1007/s00227-009-1184-3Joern Fischer, David B. Lindenmayer, Rebecca Montague-Drake The role of landscape texture in conservation biogeography: a case study on birds in south-eastern Australia, Diversity and Distributions 14, no.11 (Sep 2007): 38–46.https://doi.org/10.1111/j.1472-4642.2007.00411.xB. Gratwicke, M. R. Speight The relationship between fish species richness, abundance and habitat complexity in a range of shallow tropical marine habitats, Journal of Fish Biology 66, no.33 (Mar 2005): 650–667.https://doi.org/10.1111/j.0022-1112.2005.00629.xPer Arneberg, Johan Andersen The energetic equivalence rule rejected because of a potentially common sampling error: evidence from carabid beetles, Oikos 101, no.22 (Apr 2003): 367–375.https://doi.org/10.1034/j.1600-0706.2003.11527.x Sabrina E. Russo , Scott K. Robinson , and John Terborgh Size‐Abundance Relationships in an Amazonian Bird Community: Implications for the Energetic Equivalence Rule. S. E. Russo et al., The American Naturalist 161, no.22 (Jul 2015): 267–283.https://doi.org/10.1086/345938Tim M. Blackburn, Adriana Ruggiero Latitude, elevation and body mass variation in Andean passerine birds, Global Ecology and Biogeography 10, no.33 (Dec 2001): 245–259.https://doi.org/10.1046/j.1466-822X.2001.00237.xVicente Polo, Luis M. Carrascal Shaping the body mass distribution of Passeriformes: habitat use and body mass are evolutionarily and ecologically related, Journal of Animal Ecology 68, no.22 (Dec 2001): 324–337.https://doi.org/10.1046/j.1365-2656.1999.00282.x Per Arneberg , Arne Skorping , and Andrew F. Read Parasite Abundance, Body Size, Life Histories, and the Energetic Equivalence Rule Arneberg, Skorping, Read, The American Naturalist 151, no.66 (Jul 2015): 497–513.https://doi.org/10.1086/286136Trevor Price Correlated evolution and independent contrasts, Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 352, no.13521352 (Apr 1997): 519–529.https://doi.org/10.1098/rstb.1997.0036

Body-size distribution in a marine metazoan community and the fractal dimensions of macroalgae

Habitat architecture has two major components, size and structural variety. Both these attributes are incorporated in measurements of fractal dimensions which are essentially an expression of habitat size in relation to the scale of measurement. Therefore, the fractal dimensions of a habitat, coupled with energy requirements, may be one explanation for the species abundance/body size distribution of the associated animal assemblages. This concept is tested in the marine environment by an analysis of the fractal dimensions and epifaunal assemblages of four species of macroalgae on the Isles of Scilly. It is shown that the slope of the regression of animal abundance against body size (estimated by sieve mesh size) is related to the fractal dimension of each weed. The application of the energetic equivalence rule, however, overestimates the abundance of smaller animals. In general, smaller animals appear to use proportionately less of the community resources. It is suggested that this is a result of unequal availability of resources due to the different feeding and resource partitioning traits between macrofauna and meiofauna.

The Energetic Equivalence Hypothesis and the Relation between Population Density and Body Size in Stream-Living Salmonids

We studied density and mean body size in populations of stream-living resident brown trout Salmo trutta, anadromous populations of S. trutta, and Atlantic salmon Salmo salar in southern Sweden using annual quantitative electric fishing during time periods ranging from 2 to 16 yr in 54 sites in nine streams. With a total of 236 observations, ANCOVA of log(population density) versus log(mean body size) showed a negative dependence with an estimated slope of -0.984 ± 0.148 (95% confidence interval) and intercepts significantly varying among stream sites. As previously published data indicate the metabolic rate of fishes proportional to (body weight)0.9, the result supports the hypothesis of energetic equivalence; that is, the total energy flow through a population tends to be constant within but varying among sites and populations. In a review of the theory of self-thinning in food-regulated animals, we emphasize the effects of a negatively size-dependent growth and mortality; each will modify the thinning line, but combined they will tend to compensate for each other.

Population abundance and body size in animal assemblages

Studies of the relationship between body mass and population abundance for terrestrial and aquatic animal species based on pooling data from many taxa and assemblages suggest that abundance scales with mass to the —0.75 power. Because metabolic rate scales with mass as (plus) 0.75, this result has been taken as evidence that all species in assemblages use equal amounts of energy. The evidence for ‘energetic equivalence’ is, however, equivocal, because within many individual assemblages the scaling of abundance on mass differs significantly from —0.75. Here, we present a summary of patterns of size and abundance in a number of different terrestrial, freshwater and marine animal assemblages, with the aim of discovering whether there is any generality in size-abundance patterns within assemblages, and whether any generality might hold across terrestrial, freshwater and marine environments.

Relations between body size, abundance and taxonomy of birds wintering in Britain and Ireland

We examine the relation between body size, abundance, and taxonomy in the wintering bird assemblages in Britain and Ireland. The regression slope of abundance on body size across species in both assemblages is not significantly different from that predicted by an ‘energetic equivalence rule’, but the proportion of the variance in abundance explained by body size is very low. Previous work on breeding bird assemblages has found the novel relation that the correlation between size and abundance across species within a tribe is itself positively correlated with the degree of taxonomic isolation of the tribe from other tribes in the bird fauna. We show that the same relation holds within bird tribes in the two wintering assemblages. Furthermore, evidence for this relation is found by using two different measures of bird abundance, despite these two abundance measures showing very different correlations with body size across species. Although these patterns in the data are consistent, some are not formally statistically significant ( p = 0.089 or greater). Excluding coastal, stocked, feral and recently colonizing species increased the significance of time since origin of a tribe on species abundances. We conclude that the relation between size and abundance in bird tribes is somehow related to bird taxonomy. While acknowledging the unlikely nature of such an effect, we tentatively propose hypotheses for two mechanisms that could produce the observed patterns.

Bird Size and Density: A Regional Approach

Previous articleNext article No AccessNotes and CommentsBird Size and Density: A Regional ApproachL. M. Carrascal and J. L. TelleriaL. M. Carrascal Search for more articles by this author and J. L. Telleria Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 138, Number 3Sep., 1991 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/285250 Views: 2Total views on this site Citations: 18Citations are reported from Crossref Copyright 1991 The University of ChicagoPDF download Crossref reports the following articles citing this article:AHMAD FITRI AZIZ, CHARLIE JUSTIN MERGIE LAMAN Species Abundance and Body Size Relationship of Bird Assemblages at Selected Sites in Western Sarawak, Trends in Undergraduate Research 3, no.22 (Dec 2020): a18–25.https://doi.org/10.33736/tur.1414.2020Luis M. Carrascal, Ángel C. Moreno, Alejandro Delgado, Víctor Suárez, Domingo Trujillo Habitat suitability—density relationship in an endangered woodland species: the case of the Blue Chaffinch ( Fringilla polatzeki ), PeerJ 5 (Sep 2017): e3771.https://doi.org/10.7717/peerj.3771Luis M. Carrascal, Ismael Galván, Juan S. Sánchez-Oliver, José M. Rey Benayas Regional distribution patterns predict bird occurrence in Mediterranean cropland afforestations, Ecological Research 29, no.22 (Dec 2013): 203–211.https://doi.org/10.1007/s11284-013-1114-1Luis M. Carrascal, Luis Cayuela, David Palomino, Javier Seoane What species-specific traits make a bird a better surrogate of native species richness? A test with insular avifauna, Biological Conservation 152 (Aug 2012): 204–211.https://doi.org/10.1016/j.biocon.2012.04.009Luis M. Carrascal Data, Preconceived Notions and Methods: The Case of Population Sizes of Common Breeding Birds in Spain, Ardeola 58, no.22 (Dec 2011): 371–385.https://doi.org/10.13157/arla.58.2.2011.371J. Seoane, L.M. Carrascal, D. Palomino Assessing the ecological basis of conservation priority lists for bird species in an island scenario, Journal for Nature Conservation 19, no.22 (May 2011): 103–115.https://doi.org/10.1016/j.jnc.2010.07.002Luis M. Carrascal, Javier Seoane Linking density, productivity and trends of an endangered species: The Bonelli's eagle in Spain, Acta Oecologica 35, no.33 (May 2009): 341–348.https://doi.org/10.1016/j.actao.2009.03.003Luis M. Carrascal, Javier Seoane, David Palomino, Vicente Polo Explanations for bird species range size: ecological correlates and phylogenetic effects in the Canary Islands, Journal of Biogeography 35, no.1111 (Nov 2008): 2061–2073.https://doi.org/10.1111/j.1365-2699.2008.01958.xLuis M. Carrascal, David Palomino, Javier Seoane, César L. Alonso Habitat use and population density of the houbara bustard Chlamydotis undulata in Fuerteventura (Canary Islands), African Journal of Ecology 46, no.33 (Sep 2008): 291–302.https://doi.org/10.1111/j.1365-2028.2008.00971.xT. R. Shankar Raman, R. Sukumar Responses of tropical rainforest birds to abandoned plantations, edges and logged forest in the Western Ghats, India, Animal Conservation 5, no.33 (Aug 2002): 201–216.https://doi.org/10.1017/S1367943002002251L. M. BINI, A. S. G COELHO, J. A. F. DINIZ-FILHO, , , Is the relationship between population density and body size consistent across independent studies? 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