Bergmann's rule is invalid

1987 ◽  
Vol 65 (4) ◽  
pp. 1035-1038 ◽  
Author(s):  
Valerius Geist
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Small Body ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Large Mammals ◽  
Annual Productivity ◽  
Body Sizes ◽  
Growth Correlations

Bergmann's rule, claiming that in homeotherms body size increases inversely with temperature so that, intraspecifically, body size increases latitudinally, is not valid, nor is the explanation of this rule. In large mammals body size at first increases with latitude, but then reverses between 53 and 65° N, so that small body sizes occur at the lowest and highest latitudes. This is predicted by the hypothesis that body size follows the duration of the annual productivity pulse, so that body size is a function of availability of nutrients and energy during periods of growth. Correlations between body size and temperature are shown to be spurious. If reduction in relative surface area is indeed an adaptation to conserve heat, then mammals should increase in size from south to north at rates two orders of magnitude greater than they do. Bergmann's rule has no basis in fact or theory.

Revisiting classic ecogeographical rules, using a widely distributed mouse species (Apodemus draco)

2020 ◽  
Vol 70 (4) ◽  
pp. 359-372
Author(s):  
Jifa Cui ◽  
Bingxin Wang ◽  
Shengnan Ji ◽  
Huawei Su ◽  
Youbing Zhou
Keyword(s):  
Body Size ◽  
South China ◽  
Selective Adaptation ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Population Sampling ◽  
Body Sizes ◽  
Heart Size ◽  
Allen’S Rule ◽  
Elevational Range

Abstract Ecogeographical rules predict an association between specific adaptive morphological/physiological traits and latitude, elevation or cooler climates. Such ecogeographical effects are often expressed most clearly in widely distributed species due to continuous selective adaptation occurring over their geographic range. Based on 40 population sampling sites of 116 adult individuals (female, ; male, ) across an elevational range of 191–2573 m, we tested whether morphological traits accorded with predictions of Bergmann’s rule, Allen’s rule and Hesse’s rule for the South China field mouse (Apodemus draco). The effects of elevation on body size, appendage length and heart size were tested by fitting Linear Mixed-Effects Models. None conformed to Bergmann’s, Allen’s or Hesse’s rule. Clines in body size opposed Bergmann’s rule, and foot and snout length ratios opposed Allen’s rule. We conclude that South China field mice, a widely distributed species, exhibit an acute thermoregulation mechanism in which in colder conditions body sizes decrease – as opposed to altering heart sizes or surface area to volume ratios – requiring less energy to regulate body temperatures. Also, there was a stronger selective pressure to increase partial appendage lengths (i.e., foot and snout) to adapt to the specific environment (e.g. longer period of snow cover, up to 2573 m) rather than on a general shortening of appendages to cope with colder conditions.

The biophysics of Bergmann's rule: a comparison of the effects of pelage and body size variation on metabolic rate

1994 ◽  
Vol 72 (1) ◽  
pp. 70-77 ◽  
Author(s):  
K. Steudel ◽  
W. P. Porter ◽  
D. Sher
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Small Mammals ◽  
Seasonal Changes ◽  
Size Variation ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Large Mammals ◽  
Size Change ◽  
Biomechanical Constraints

Should an animal extending its range into a cooler climate rely most on pelage or on body size change to minimize its mass-specific metabolic rate? The various examples of animals following Bergmann's rule support the latter. The fact that an increase in size will result in an increase in total metabolic rate (though coupled to the decrease in the mass-specific metabolic rate) suggests that increases in the insulative value of the pelage would be the preferred strategy. We used a thermal simulation model to compare the relative effects of increasing body mass versus increasing pelage insulative properties on the mass-specific metabolic rate. We found that even the fur of summer-adapted small mammals from temperate climates is extremely dense compared with that of larger mammals and is near the point at which increases in density increase, rather than decrease, heat loss as a result of the high conductivity of individual hairs compared with the layer of still air that it encloses. Small mammals also have lower fur depths, presumably as a result of biomechanical constraints. Seasonal changes in pelage observed in small mammals have very modest effects on mass-specific metabolism. Summer-adapted temperate large mammals, however, are less heavily insulated and, consequently, have substantial latitude for increasing insulation as a means of minimizing mass-specific metabolism. Thus, Bergmann's rule should be more relevant to small mammals than to large ones.

An interspecific test of Bergmann's rule reveals inconsistent body size patterns across several lineages of water beetles (Coleoptera: Dytiscidae)

2018 ◽  
Vol 44 (2) ◽  
pp. 249-254 ◽  
Author(s):  
Susana Pallarés ◽  
Michele Lai ◽  
Pedro Abellán ◽  
Ignacio Ribera ◽  
David Sánchez-Fernández
Keyword(s):  
Body Size ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Water Beetles

Latitudinal body-mass trends in Oligo-Miocene mammals

Paleobiology ◽  
2016 ◽  
Vol 42 (4) ◽  
pp. 643-658
Author(s):  
John D. Orcutt ◽  
Samantha S. B. Hopkins
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Regional Scale ◽  
Latitudinal Gradients ◽  
Bergmann’S Rule ◽  
Strongly Correlated ◽  
Bergmann's Rule ◽  
Deep Time ◽  
Causal Factors ◽  
Primary Driver

AbstractPaleecological data allow not only the study of trends along deep-time chronological transects but can also be used to reconstruct ecological gradients through time, which can help identify causal factors that may be strongly correlated in modern ecosystems. We have applied such an analysis to Bergmann’s rule, which posits a causal relationship between temperature and body size in mammals. Bergmann’s rule predicts that latitudinal gradients should exist during any interval of time, with larger taxa toward the poles and smaller taxa toward the equator. It also predicts that the strength of these gradients should vary with time, becoming weaker during warmer periods and stronger during colder conditions. We tested these predictions by reconstructing body-mass trends within canid and equid genera at different intervals of the Oligo-Miocene along the West Coast of North America. To allow for comparisons with modern taxa, body mass was reconstructed along the same transect for modernCanisandOdocoileus. Of the 17 fossil genera analyzed, only two showed the expected positive relationship with latitude, nor was there consistent evidence for a relationship between paleotemperature and body mass. Likewise, the strength of body-size gradients does not change predictably with climate through time. The evidence for clear gradients is ambiguous even in the modern genera analyzed. These results suggest that, counter to Bergmann’s rule, temperature alone is not a primary driver of body size and underscore the importance of regional-scale paleoecological analyses in identifying such drivers.

Reproductive performance in a phyletic dwarf, the spider crab Petramithrax pygmaeus (Bell, 1836) (Decapoda: Brachyura: Mithracidae)

2020 ◽  
Vol 40 (3) ◽  
pp. 325-329
Author(s):  
Joshua T Fields ◽  
Hayden K Mullen ◽  
Clayr M Kroenke ◽  
Kyla A Salomon ◽  
Abby J Craft ◽  
...  
Keyword(s):  
Body Size ◽  
Reproductive Performance ◽  
Related Species ◽  
Egg Production ◽  
Marine Invertebrates ◽  
Small Body ◽  
Reproductive Investment ◽  
Spider Crab ◽  
Closely Related Species ◽  
Body Sizes

Abstract The spider crab Petramithrax pygmaeus (Bell, 1836), a phyletic dwarf, was used to test predictions regarding reproductive performance in small marine invertebrates. Considering the disproportional increase in brooding costs and the allometry of egg production with increasing body size, it was expected that this minute-size species would produce large broods compared to closely related species that attain much larger body sizes. Fecundity in P. pygmaeus females carrying early and late eggs varied, respectively, between 17 and 172 eggs crab–1 (mean ± SD = 87.97 ± 48.39) and between 13 and 159 eggs crab–1 (55.04 ± 40.29). Females did not experience brood loss during egg development. Egg volume in females carrying early and late eggs varied, respectively, between 0.13 and 0.40 mm3 (0.22 ± 0.07) and between 0.15 and 0.42 mm3 (0.26 ± 0.06 mm3). Reproductive output (RO) varied between 0.91 and 8.73% (3.81 ± 2.17%) of female dry body weight. The RO of P. pygmaeus was lower than that reported for closely related species with larger body sizes. The slope (b = 0.95 ± 0.15) of the line describing the relationship between brood and parental female dry weight was not statistically significant from unity. Overall, our results disagree with the notion that the allometry of gamete production and increased physiological costs with increased brood size explain the association between brooding and small body size in marine invertebrates. Comparative studies on the reproductive investment of brooding species belonging to monophyletic clades with extensive differences in body size are warranted to further our understanding about disparity in egg production in brooding marine invertebrates.

scholarly journals Functional diversity of small-mammal postcrania is linked to both substrate preference and body size

2020 ◽  
Vol 66 (5) ◽  
pp. 539-553
Author(s):  
Lucas N Weaver ◽  
David M Grossnickle
Keyword(s):  
Body Size ◽  
Phenotypic Diversity ◽  
Small Body ◽  
Ecological Factors ◽  
Morphological Divergence ◽  
Functional Diversification ◽  
Evolutionary Patterns ◽  
Selective Pressures ◽  
Trade Offs ◽  
Body Sizes

Abstract Selective pressures favor morphologies that are adapted to distinct ecologies, resulting in trait partitioning among ecomorphotypes. However, the effects of these selective pressures vary across taxa, especially because morphology is also influenced by factors such as phylogeny, body size, and functional trade-offs. In this study, we examine how these factors impact functional diversification in mammals. It has been proposed that trait partitioning among mammalian ecomorphotypes is less pronounced at small body sizes due to biomechanical, energetic, and environmental factors that favor a “generalist” body plan, whereas larger taxa exhibit more substantial functional adaptations. We title this the Divergence Hypothesis (DH) because it predicts greater morphological divergence among ecomorphotypes at larger body sizes. We test DH by using phylogenetic comparative methods to examine the postcranial skeletons of 129 species of taxonomically diverse, small-to-medium-sized (<15 kg) mammals, which we categorize as either “tree-dwellers” or “ground-dwellers.” In some analyses, the morphologies of ground-dwellers and tree-dwellers suggest greater between-group differentiation at larger sizes, providing some evidence for DH. However, this trend is neither particularly strong nor supported by all analyses. Instead, a more pronounced pattern emerges that is distinct from the predictions of DH: within-group phenotypic disparity increases with body size in both ground-dwellers and tree-dwellers, driven by morphological outliers among “medium”-sized mammals. Thus, evolutionary increases in body size are more closely linked to increases in within-locomotor-group disparity than to increases in between-group disparity. We discuss biomechanical and ecological factors that may drive these evolutionary patterns, and we emphasize the significant evolutionary influences of ecology and body size on phenotypic diversity.

Body Size, Adaptation and Function

1989 ◽  
Vol 48 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Reynaldo Martorell
Keyword(s):  
Developing Countries ◽  
Body Size ◽  
Cognitive Development ◽  
Growth Retardation ◽  
Small Body ◽  
Warning Signal ◽  
Increased Risk ◽  
Body Sizes ◽  
And Function ◽  
Excellent Tool

This is a brief discussion of the "small but healthy" hypothesis proposed by David Seckler in the early 1980s. Four basic points are made. First, adults in developing countries have small body sizes largely as a result of poor diets and infection during childhood. Therefore, to acclaim small body sizes as a desirable attribute for populations is also to affirm that its causes are desirable. Second, monitoring the growth of children is widely recognized as an excellent tool for detecting health problems. Growth retardation, rather than an innocuous response to environmental stimuli, is a warning signal of increased risk of morbidity and mortality. Third, the conditions which give rise to stunted children also affect other aspects such as cognitive development. Finally, stunted girls who survive to be short women are at greater risk of delivering growth retarded infants with a greater probability of dying in infancy. For all these reasons, small is not healthy.

Bergmann’s rule for Neomys fodiens in the middle of the distribution range

2014 ◽  
Vol 9 (12) ◽  
pp. 1147-1154 ◽  
Author(s):  
Linas Balčiauskas ◽  
Laima Balčiauskienė ◽  
Uudo Timm
Keyword(s):  
Body Size ◽  
The Body ◽  
Distribution Range ◽  
Bergmann’S Rule ◽  
Bergmann's Rule ◽  
Range Analysis ◽  
Skull Size ◽  
Skull Measurements ◽  
The Brain ◽  
Neomys Fodiens

AbstractThe body size of Palearctic Sorex shrews decreases at higher latitudes, and as such the Bergmann’s rule does not work. However, no analysis has ever been done for water shrew (Neomys fodiens) in the middle of distribution range. Analysis of available literature data showed that some body and skull measurements of N. fodiens are negatively correlated to latitude. Measurements of 158 water shrews from Estonia and Lithuania were also analyzed with respect to the short scale latitudinal pattern. We found that populations are separated (Wilk’s lambda = 0.363, p<0.0001). Differences are related to PC1 (skull size), explaining 49.80% of the variance and PC2 (body size), explaining 10.06% of the variance. Estonian shrews are smaller in their body and skull (most differences significant) and their skulls are relatively shorter and wider in the area of the brain case. Thus, the negative correlation of body and skull size to latitude in N. fodiens is applicable even over quite short latitudinal distances. Further analysis of diagnostic characters between N. fodiens and N. anomalus is required.

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